Papers on tropopause height

This is a list of papers on tropopause height. The list is not complete, and will most likely be updated in future in order to make it more thorough and more representative.

UPDATE (May 12, 2013): Lakkis et al. (2009) added.

The determination of extratropical tropopause height in an idealized gray-radiation model – Zurita-Gotor & Vallis (2013) “This paper investigates the mechanisms that determine the extratropical tropopause height, extending previous results with a Newtonian cooling model. A primitive equation model forced by a meridional gradient of incoming solar radiation, with the outgoing infra-red radiation calculated using a simple gray radiation scheme, is now used. The tropopause is defined as the top of the boundary layer over which dynamical heat transport moves the temperature away from radiative equilibrium, and its height estimated from the isentropic mass flux. Depending on parameters, this tropopause may or may not be associated with a sharp stratification change, and it may or may not be possible to define a thermal tropopause. The mass flux and thermal tropopause display similar sensitivity to external parameters when the latter can be defined, a sensitivity in good agreement with predictions by a radiative constraint. In some contrast to the Newtonian model, the radiative constraint is now quite effective in preventing adjustment to marginal criticality with realistic parameters. The meridional structure of the thermal tropopause displays a jump in height at the jet latitude, which appears to be due to the formation of a mixing barrier at the jet maximum when baroclinicity has a finite vertical scale. As meridional potential vorticity mixing is inhibited across the jet, a discontinuity is created between weakly stratified air on its warm side and strongly stratified air on its cool side. The meridional stratification contrast is created by adiabatic cooling and warming by the residual circulation, as this circulation must be deflected vertically to avoid the mixing barrier at the jet maximum.” Pablo Zurita-Gotor, Geoffrey K. Vallis, Journal of the Atmospheric Sciences 2013, doi: http://dx.doi.org/10.1175/JAS-D-12-0209.1.

A numerical simulation of aerosols’ direct effects on tropopause height – Wu et al. (2013) “The direct effects of sulfate aerosol, dust aerosol, carbonaceous aerosol, and total combined aerosols on the tropopause height are simulated with the Community Atmospheric Model version 3.1 (CAM3.1). A decrease of global mean tropopause height induced by sulfate, carbonaceous aerosol, and total combined aerosols is found, and a tropopause height increase is induced by dust aerosol. Sulfate aerosol decreases the tropospheric temperature and increases the stratospheric temperature. These effects cause a decrease in the height of the tropopause. In contrast, carbonaceous and total combined aerosols increase both the tropospheric and the stratospheric temperatures, and they also cause a decrease in the height of the tropopause. The changes in the tropopause height show highly statistically significant correlations with the changes in the tropospheric and stratospheric temperatures. The changes in the tropospheric and stratospheric temperatures are related to the changes in the radiative heat rate, cloud cover, and latent heat, but none of these factors absolutely dominate the temperature change.” Jian Wu, Yanyan Xu, Qian Yang, Zhiwei Han, Deming Zhao, Jianping Tang, Theoretical and Applied Climatology, May 2013, Volume 112, Issue 3-4, pp 659-671, DOI: 10.1007/s00704-012-0760-5.

A global blended tropopause based on ERA data. Part II: Trends and tropical broadening – Wilcox et al. (2012) “A new tropopause definition involving a flow-dependent blending of the traditional thermal tropopause with one based on potential vorticity has been developed and applied to the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses (ERA), ERA-40 and ERA-Interim. Global and regional trends in tropopause characteristics for annual and solsticial seasonal means are presented here, with emphasis on significant results for the newer ERA-Interim data for 1989–2007. The global-mean tropopause is rising at a rate of 47 m per decade, with pressure falling at 1.0 hPa per decade and temperature falling at 0.18 K per decade. The Antarctic tropopause shows decreasing heights, warming and increasing westerly winds. The Arctic tropopause also shows a warming, but with decreasing westerly winds. In the Tropics the trends are small, but at the latitudes of the subtropical jets they are almost double the global values. It is found that these changes are mainly concentrated in the eastern hemisphere. Previous and new metrics for the rate of broadening of the Tropics, based on both height and wind, give trends in the range 0.9–2.2° per decade. For ERA-40 the global height and pressure trends for the period 1979–2001 are similar: 39 m per decade and −0.8 hPa per decade. These values are smaller than those found from the thermal tropopause definition with this dataset, as was used in most previous studies.” L. J. Wilcox, B. J. Hoskins, K. P. Shine, Quarterly Journal of the Royal Meteorological Society, Volume 138, Issue 664, pages 576–584, April 2012 Part A, DOI: 10.1002/qj.910. [Full text]

A global blended tropopause based on ERA data. Part I: Climatology – Wilcox et al. (2012) “A new tropopause definition, based on a flow-dependent blending of the traditional thermal tropopause with one based on potential vorticity, has been developed. The benefits of such a blending algorithm are most apparent in regions with synoptic-scale fluctuations between tropical and extratropical air masses. The properties of the local air mass determine the relative contributions to the location of the blended tropopause, rather than this being determined by a specified function of latitude. Global climatologies of tropopause height, temperature, potential temperature and zonal wind, based on European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA) ERA-Interim data, are presented for the period 1989–2007. Features of the seasonal-mean tropopause are discussed on a global scale, alongside a focus on selected monthly climatologies for the two high-latitude regions and the tropical belt. The height differences between climatologies based on ERA-Interim and ERA-40 data are also presented. Key spatial and temporal features seen in earlier climatologies, based mainly on the World Meteorological Organization thermal tropopause definition, are reproduced with the new definition. Tropopause temperatures are consistent with those from earlier climatologies, despite some differences in height in the extratropics.” L. J. Wilcox, B. J. Hoskins, K. P. Shine, Quarterly Journal of the Royal Meteorological Society, Volume 138, Issue 664, pages 561–575, April 2012 Part A, DOI: 10.1002/qj.951.

Monitoring Cirrus Cloud and Tropopause Height over Hanoi Using a Compact Lidar System – Hai et al. (2012) “Cirrus clouds in the upper troposphere and the lower stratosphere have attracted great attention due to their important role and impact on the atmospheric radioactive balance. Because cirrus clouds are located high in the atmosphere, their study requires a high resolution remote sensing technique not only for detection but also for the characterization of their properties. The lidar technique with its inherent high sensitivity and resolution has become an indispensible tool for studying and improving our understanding of cirrus cloud. Using lidar technique we can simultaneously measure the cloud height, thickness and follow its temporal evolution. In this paper we describe the development of a compact and highly sensitive lidar system with the aim to remotely monitor for the first time the cirrus clouds over Hanoi (21⁰01’42’’N, 105⁰51’12’’W). From the lidar data collected during the year 2011. We derive the mean cloud height, location of cloud top, the cloud mean thickness and their temporal evolution. We then compare the location of the cloud top with the position of the tropopause determined the radiosonde data and found good that the distance between cloud top and tropopause remains fairly stable, indicating that generally the top of cirrus clouds is the good tracer of the tropopause. We found that the cirrus clouds are generally located at height between 11.2 to 15 km with average height of 13.4 km. Their thickness is between 0.3 and 3.8 km with average value of 1.7 km. We also compare the properties of cirrus cloud with that observed at other locations around the world based on lidar technique.” Bui Van Hai, Dinh Van Trung, Nguyen Xuan Tuan, Dao Duy Thang, Nguyen Thanh Binh, Communications in Physics, Vol 22, No 4 (2012).

Dynamics of Midlatitude Tropopause Height in an Idealized Model – Zurita-Gotor & Vallis (2011) “This paper investigates the factors that determine the equilibrium state, and in particular the height and structure of the tropopause, in an idealized primitive equation model forced by Newtonian cooling in which the eddies can determine their own depth. Previous work has suggested that the midlatitude tropopause height may be understood as the intersection between a radiative and a dynamical constraint. The dynamical constraint relates to the lateral transfer of energy, which in midlatitudes is largely effected by baroclinic eddies, and its representation in terms of mean-flow properties. Various theories have been proposed and investigated for the representation of the eddy transport in terms of the mean flow, including a number of diffusive closures and the notion that the flow evolves to a state marginally supercritical to baroclinic instability. The radiative constraint expresses conservation of energy and so must be satisfied, although it need not necessarily be useful in providing a tight constraint on tropopause height. This paper explores whether and how the marginal criticality and radiative constraints work together to produce an equilibrated flow and a tropopause that is internal to the fluid. The paper investigates whether these two constraints are consistent with simulated variations in the tropopause height and in the mean state when the external parameters of an idealized primitive equation model are changed. It is found that when the vertical redistribution of heat is important, the radiative constraint tightly constrains the tropopause height and prevents an adjustment to marginal criticality. In contrast, when the stratification adjustment is small, the radiative constraint is only loosely satisfied and there is a tendency for the flow to adjust to marginal criticality. In those cases an alternative dynamical constraint would be needed in order to close the problem and determine the eddy transport and tropopause height in terms of forcing and mean flow.” Zurita-Gotor, Pablo, Geoffrey K. Vallis, 2011: Dynamics of Midlatitude Tropopause Height in an Idealized Model. J. Atmos. Sci., 68, 823–838. doi: http://dx.doi.org/10.1175/2010JAS3631.1. [Full text]

Recent widening of the tropical belt from global tropopause statistics: Sensitivities – Birner et al. (2010) “Several recent studies have shown evidence for a widening of the tropical belt over the past few decades. One line of evidence uses statistics of the tropopause height to distinguish between tropics and extratropics and defines tropical edge latitudes as those latitudes at which the number of days per year with tropopause heights greater than 15 km exceeds a certain threshold (typically 200 days/yr). This definition involves two somewhat arbitrary thresholds. Here the sensitivity of the resulting widening trend of the tropical belt to these thresholds is investigated using four different reanalysis data sets. Widening trends are found to be particularly sensitive to changes in the tropopause height threshold. Ways to objectively determine appropriate thresholds to define tropical edge latitudes based on tropopause statistics are presented. Trend estimates for the width of the tropical belt from different reanalysis data sets are found to be mostly inconsistent with each other despite consistent seasonal and interannual variations.” Thomas Birner, Journal of Geophysical Research: Atmospheres (1984–2012), Volume 115, Issue D23, 16 December 2010, DOI: 10.1029/2010JD014664. [Full text]

The Impact of Stratospheric Ozone Recovery on Tropopause Height Trends – Son et al. (2009) “The evolution of the tropopause in the past, present, and future climate is examined by analyzing a set of long-term integrations with stratosphere-resolving chemistry climate models (CCMs). These CCMs have high vertical resolution near the tropopause, a model top located in the mesosphere or above, and, most important, fully interactive stratospheric chemistry. Using such CCM integrations, it is found that the tropopause pressure (height) will continue to decrease (increase) in the future, but with a trend weaker than that in the recent past. The reduction in the future tropopause trend is shown to be directly associated with stratospheric ozone recovery. A significant ozone recovery occurs in the Southern Hemisphere lower stratosphere of the CCMs, and this leads to a relative warming there that reduces the tropopause trend in the twenty-first century. The future tropopause trends predicted by the CCMs are considerably smaller than those predicted by the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) models, especially in the southern high latitudes. This difference persists even when the CCMs are compared with the subset of the AR4 model integrations for which stratospheric ozone recovery was prescribed. These results suggest that a realistic representation of the stratospheric processes might be important for a reliable estimate of tropopause trends. The implications of these finding for the Southern Hemisphere climate change are also discussed.” Son, Seok-Woo, and Coauthors, 2009: The Impact of Stratospheric Ozone Recovery on Tropopause Height Trends. J. Climate, 22, 429–445. doi: http://dx.doi.org/10.1175/2008JCLI2215.1. [Full text]

Monitoring cirrus clouds with lidar in the Southern Hemisphere: A local study over Buenos Aires. 1. Tropopause heights – Lakkis et al. (2009) “Cirrus clouds in the upper troposphere and the lower stratosphere have recently drawn much attention due to their important role and impact on the atmospheric radiative balance. Because they are located in the upper troposphere their study requires a high resolution technique not only to detect them but also to characterize their behaviour and evolution. A good dynamic range in lidar backscattering signals is necessary to observe and improve our knowledge of cirrus clouds, and thereof, atmospheric parameters in the troposphere and UT/LS due to their vicinity to the tropopause layer. The lidar system measures, in real time, the evolution of the atmospheric boundary layer, stratospheric aerosols, tropopause height and cirrus clouds evolution. The aim of the work is to present the main properties of cirrus clouds over central Argentina and to monitor tropopause height together with their temporal evolution using a backscatter lidar system located in Buenos Aires (34.6 °S, 58.5 °W). A cirrus clouds detection method was used to analyze a set of 60 diurnal events, during 2001–2005, in order to estimate tropopause height and its temporal evolution, using the top of cirrus clouds present on the upper troposphere as a tropopause tracer. The results derived from lidar show a remarkable good agreement when compared with rawinsonde data, considering values of tropopause height with differences less than or equal to 500 m, depending on the signal to noise ratio of the measurements. Clouds properties analysis reveals the presence of thick cirrus clouds with thickness between 0.5 and 4.2 km, with the top cloud located at the tropopause height.” Susan Gabriela Lakkis, Mario Lavorato, Pablo Osvaldo Canziani, Atmospheric Research, Volume 92, Issue 1, March 2009, Pages 18–26, http://dx.doi.org/10.1016/j.atmosres.2008.08.003. [Full text]

Tropopause height and zonal wind response to global warming in the IPCC scenario integrations – Lorenz & DeWeaver (2007) “The change in the extratropical circulation under global warming is studied using the climate models participating in the Intergovernmental Panel on Climate Change (IPCC) fourth assessment report. The IPCC models predict a strengthening and a poleward shift of the tropospheric zonal jets in response to global warming. The change in zonal jets is also accompanied by a strengthening and a poleward and upward shift of transient kinetic energy and momentum flux. Similar changes in circulation are simulated by a simple dry general circulation model (GCM) when the height of the tropopause is raised. The similarity between the simple GCM and the IPCC models suggests that the changes in midlatitude circulation are predominantly driven by a rise in the height of the tropopause, and that other factors such as increased moisture content and the change in the low-level pole-to-equator temperature gradient, play a secondary role. In addition, the variability about the ensemble-mean of the zonal wind response is significantly correlated with the variability of the tropopause height response over the polar cap, especially in the Southern Hemisphere.” David J. Lorenz, Eric T. DeWeaver, Journal of Geophysical Research: Atmospheres (1984–2012), Volume 112, Issue D10, 27 May 2007, DOI: 10.1029/2006JD008087. [Full text]

Contributions of Anthropogenic and Natural Forcing to Recent Tropopause Height Changes – Santer et al. (2003) “Observations indicate that the height of the tropopause—the boundary between the stratosphere and troposphere—has increased by several hundred meters since 1979. Comparable increases are evident in climate model experiments. The latter show that human-induced changes in ozone and well-mixed greenhouse gases account for ∼80% of the simulated rise in tropopause height over 1979–1999. Their primary contributions are through cooling of the stratosphere (caused by ozone) and warming of the troposphere (caused by well-mixed greenhouse gases). A model-predicted fingerprint of tropopause height changes is statistically detectable in two different observational (“reanalysis”) data sets. This positive detection result allows us to attribute overall tropopause height changes to a combination of anthropogenic and natural external forcings, with the anthropogenic component predominating.” B. D. Santer, M. F. Wehner, T. M. L. Wigley, R. Sausen, G. A. Meehl, K. E. Taylor, C. Ammann, J. Arblaster, W. M. Washington, J. S. Boyle, W. Brüggemann, Science 25 July 2003: Vol. 301 no. 5632 pp. 479-483, DOI: 10.1126/science.1084123. [Full text]

Use of changes in tropopause height to detect human influences on climate – Sausen & Santer (2003) “The height of the global-mean tropopause shows a steady increase since 1979 in re-analyses of numerical weather forecasts. This is in agreement with results from a climate model driven by natural and anthropogenic forcings. Superimposed on the multi-decadal overall trends in both simulations and re-analyses are higher-frequency fluctuations (with periods of few years) related to explosive volcanic eruptions. Global-mean tropopause height has the desirable property of acting as a natural filter, removing much of the ENSO variability that hampers the interpretation of tropospheric and surface temperature changes. In model simulations with anthropogenic forcings, changes in tropopause height can be detected roughly 20 years earlier than changes in surface temperature.” Sausen, Robert; Santer, Benjamin D., Meteorologische Zeitschrift, Volume 12, Number 3, 1 June 2003 , pp. 131-136(6), DOI: http://dx.doi.org/10.1127/0941-2948/2003/0012-0131.

Determining the tropopause height from gridded data – Reichler et al. (2003) “A method is presented to determine tropopause height from gridded temperature data with coarse vertical resolution. The algorithm uses a thermal definition of the tropopause, which is based on the concept of a “threshold lapse-rate”. Interpolation is performed to identify the pressure at which this threshold is reached and maintained for a prescribed vertical distance. The method is verified by comparing the heights calculated from analyses of the European Centre for Medium-Range Weather Forecasts (ECMWF) with the observed heights at individual radiosonde stations. RMS errors in the calculated tropopause heights are generally small. They range from 30–40 hPa in the extratropics to 10–20 hPa in the tropics. The largest deviations occur in the subtropics, where the tropopause has strong meridional gradients that are not adequately resolved by the input data.” Thomas Reichler, Martin Dameris, Robert Sausen, Geophysical Research Letters, Volume 30, Issue 20, October 2003, DOI: 10.1029/2003GL018240. [Full text]

Behavior of tropopause height and atmospheric temperature in models, reanalyses, and observations: Decadal changes – Santer et al. (2003) “We examine changes in tropopause height, a variable that has hitherto been neglected in climate change detection and attribution studies. The pressure of the lapse rate tropopause, p_LRT, is diagnosed from reanalyses and from integrations performed with coupled and uncoupled climate models. In the National Centers for Environmental Prediction (NCEP) reanalysis, global-mean p_LRT decreases by 2.16 hPa/decade over 1979–2000, indicating an increase in the height of the tropopause. The shorter European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis has a global-mean p_LRT trend of −1.13 hPa/decade over 1979–1993. Simulated p_LRT trends over the past several decades are consistent with reanalysis results. Superimposed on the overall increase in tropopause height in models and reanalyses are pronounced height decreases following the eruptions of El Chichón and Pinatubo. Interpreting these p_LRT results requires knowledge of both T(z), the initial atmospheric temperature profile, and ΔT(z), the change in this profile in response to external forcing. T(z) has a strong latitudinal dependence, as does ΔT(z) for forcing by well-mixed greenhouse gases and stratospheric ozone depletion. These dependencies help explain why overall tropopause height increases in reanalyses and observations are amplified toward the poles. The pronounced increases in tropopause height in the climate change integrations considered here indicate that even AGCMs with coarse vertical resolution can resolve relatively small externally forced changes in tropopause height. The simulated decadal-scale changes in p_LRT are primarily thermally driven and are an integrated measure of the anthropogenically forced warming of the troposphere and cooling of the stratosphere. Our algorithm for estimating p_LRT (based on a thermal definition of tropopause height) is sufficiently sensitive to resolve these large-scale changes in atmospheric thermal structure. Our results indicate that the simulated increase in tropopause height over 1979–1997 is a robust, zero-order response of the climate system to forcing by well-mixed greenhouse gases and stratospheric ozone depletion. At the global-mean level, we find agreement between the simulated decadal-scale p_LRT changes and those estimated from reanalyses. While the agreement between simulated p_LRT changes and those in NCEP is partly fortuitous (due to excessive stratospheric cooling in NCEP), it is also driven by real pattern similarities. Our work illustrates that changes in tropopause height may be a useful “fingerprint” of human effects on climate and are deserving of further attention.” B. D. Santer, R. Sausen, T. M. L. Wigley, J. S. Boyle, K. AchutaRao, C. Doutriaux, J. E. Hansen, G. A. Meehl, E. Roeckner, R. Ruedy, G. Schmidt, K. E. Taylor, Journal of Geophysical Research: Atmospheres (1984–2012), Volume 108, Issue D1, pages ACL 1-1–ACL 1-22, 16 January 2003, DOI: 10.1029/2002JD002258.

Interannual variability of the tropical tropopause derived from radiosonde data and NCEP reanalyses – Randel et al. (2003) “Interannual variability of the tropical tropopause is studied using long time series of radiosonde data, together with global tropopause analyses from the National Centers for Environmental Prediction (NCEP) reanalyses over 1957–1997. Comparisons for the period 1979–1997 show the NCEP tropopause temperature is too warm by ∼3–5 K and too high in pressure by ∼2–6 mbar. However, these biases are approximately constant in time, so that seasonal and interannual variability is reasonably well captured by the NCEP data. Systematic differences in NCEP tropopause statistics are observed between the presatellite (1957–1978) and postsatellite (1979–1997) periods, precluding the use of the reanalyses for the study of multidecadal variability. Interannual anomalies in tropical average radiosonde and NCEP data show variations of order ±1–2 K over the period 1979–1997, but there can be differences between these two estimates which are of similar magnitude. These differences impact estimates of decadal trends: During 1979–1997, negative trends in tropopause temperature of order −0.5 K/decade are observed in radiosonde data but are not found in NCEP reanalyses. The space-time patterns of several coherent signals are identified in both sets of tropopause statistics. The volcanic eruption of El Chichón (1982) warmed the tropical tropopause by ∼1–2 K and lowered its altitude by ∼200 m for approximately 1–2 years. Smaller tropopause variations are observed following Mount Pinatubo (1991), particularly in radiosonde data. The signatures of the quasi-biennial oscillation (QBO) and El-Nino/Southern Oscillation (ENSO) events are strong in tropopause statistics. QBO variations are primarily zonal mean in character, while ENSO events exhibit dipole patterns over Indonesia and the central Pacific Ocean, with small signals for zonal averages.” William J. Randel, Fei Wu, Dian J. Gaffen, Journal of Geophysical Research: Atmospheres (1984–2012), Volume 105, Issue D12, pages 15509–15523, 27 June 2000, DOI: 10.1029/2000JD900155. [Full text]

Climatological characteristics of the tropical tropopause as revealed by radiosondes – Seidel et al. (2001) “A temporally and spatially comprehensive depiction of the tropical tropopause is presented, based on radiosonde data from 83 stations. Climatological statistics for 1961–1990 are computed for three levels: the conventional lapse-rate tropopause (LRT), the cold-point tropopause (CPT), and the 100 hPa level. Mean values and seasonal and interannual variations of temperature, pressure, height, potential temperature, and water vapor saturation mixing ratio at these levels are compared. The tropopause is higher, colder, and at lower pressure in the Northern Hemisphere (NH) than in the Southern Hemisphere (SH) in NH winter. This pattern reverses in NH summer, except that the tropopause remains colder in the NH than in the SH. The climatological locations of minimum tropopause temperature differ from those of maximum height and minimum pressure: In NH winter the tropopause is coldest over the western tropical Pacific warm pool region, but it is highest and at lowest pressure over the western Atlantic. Correlations of interannual anomalies in zonal-mean characteristics reveal that the height of the tropopause reflects the temperature of the underlying troposphere. Tropopause temperature, on the other hand, shows little association with tropospheric characteristics but is significantly correlated with the temperature and pressure of the lower stratosphere. The 100 hPa level is a poor surrogate for the tropical tropopause. Changes in radiosonde instrumentation limit the potential for detecting tropopause trends. However, the following (nonmonotonic) trends in the tropopause in the deep tropics during 1978–1997 seem robust: an increase in height of about 20 m decade⁻¹, a decrease in pressure of about 0.5 hPa decade⁻¹, a cooling of about 0.5 K decade⁻¹, little change in potential temperature, and a decrease in saturation volume mixing ratio of about 0.3 ppmv decade⁻¹.” Dian J. Seidel, Rebecca J. Ross, James K. Angell, George C. Reid, Journal of Geophysical Research: Atmospheres (1984–2012), Volume 106, Issue D8, pages 7857–7878, 27 April 2001, DOI: 10.1029/2000JD900837. [Full text]

Stratospheric Influence on Tropopause Height: The Radiative Constraint – Thuburn & Craig (2000) “Earlier theoretical and modeling work introduced the concept of a radiative constraint relating tropopause height to tropospheric lapse rate and other factors such as surface temperature. Here a minimal quantitative model for the radiative constraint is presented and used to illustrate the essential physics underlying the radiative constraint, which involves the approximate balance between absorption and emission of thermal infrared (IR) radiation determining tropopause temperature. The results of the minimal model are then extended in two ways. First, the effects of including a more realistic treatment of IR radiation are quantified. Second, the radiative constraint model is extended to take into account non-IR warming processes such as solar heating and dynamical warming near the tropopause. The sensitivity of tropopause height to non-IR warming is estimated to be a few kilometers per K day⁻¹, with positive warming leading to a lower tropopause. Sensitivities comparable to this are found in GCM experiments in which imposed changes in the ozone distribution or in the driving of the stratospheric residual mean meridional circulation lead to changes in tropopause height. In the Tropics the influence of the stratospheric circulation is found to extend down at least as far as the main convective outflow level, some 5 km below the temperature minimum.” Thuburn, John, George C. Craig, 2000: Stratospheric Influence on Tropopause Height: The Radiative Constraint. J. Atmos. Sci., 57, 17–28. doi: http://dx.doi.org/10.1175/1520-0469(2000)0572.0.CO;2. [Full text]

Correlations between tropopause height and total ozone: Implications for long-term changes – Steinbrecht et al. (1998) “For the central European station of Hohenpeissenberg, averaging of ozone profiles grouped by tropopause height shows that the ozone mixing ratio profile in the lower stratosphere shifts up and down with the tropopause. The shift is largest near the tropopause and becomes negligible above 20 to 25 km. As a consequence a high tropopause is correlated with low total ozone and a low tropopause with high total ozone. Independent of season, total ozone decreases by 16 Dobson units (DU) per kilometer increase in tropopause height. At Hohenpeissenberg the tropopause has moved up by 150±70 m (2 σ) per decade over the last 30 years. If the −16 DU per kilometer correlation between total ozone and tropopause height is valid on the timescale of years, it is speculated that the observed increase in tropopause height could explain about 25% of the observed −10 DU per decade decrease of total ozone. This is of the same magnitude as the 30% fraction of midlatitude ozone depletion which current stratospheric models have difficulty accounting for. For Hohenpeissenberg the increase in tropopause height appears to be correlated with observed tropospheric warming: At 5 km altitude, for example, temperature has increased by 0.7±0.3 K per decade (2 σ) since 1967.” W. Steinbrecht, H. Claude, U. Köhler, K. P. Hoinka, Journal of Geophysical Research: Atmospheres (1984–2012), Volume 103, Issue D15, pages 19183–19192, 20 August 1998, DOI: 10.1029/98JD01929.

A comparison of ozone and thermal tropopause heights and the impact of tropopause definition on quantifying the ozone content of the troposphere – Bethan et al. (1996) “A comparison has been conducted of the height and sharpness of the tropopause as revealed by temperature and ozone profiles. In the study, 628 ECC-type ozonesonde profiles from four stations in northern Europe were used. Two tropopauses were defined for each profile: a thermal tropopause and an ozone tropopause defined in terms of both mixing ratio and vertical gradient of mixing ratio. On average, the ozone tropopause lay 800 m below the thermal. Large differences in tropopause height were associated with indefinite thermal tropopauses which were, in turn, often associated with cyclonic conditions (some corresponding to profiles taken within the stratospheric polar vortex). On almost all profiles the thermal tropopause was the higher of the two, and of the 15 profiles that did not fit this pattern, two-thirds were associated with anticyclonic flow in the upper troposphere. It is also shown that the tropopause definition impacts greatly on the evaluation of the ozone content of the troposphere. Where the thermal tropopause is indefinite in character, on average 27% of the ozone found below the thermal tropopause lies above the ozone tropopause.” S. Bethan, G. Vaughan, S. J. Reid, Quarterly Journal of the Royal Meteorological Society, Volume 122, Issue 532, pages 929–944, April 1996 Part B, DOI: 10.1002/qj.49712253207.

On the Height of the Tropopause and the Static Stability of the Troposphere – Held (1982) “Speculative arguments are, presented that describe how radiative and dynamical constraints conspire to determine the height of the tropopause and the tropospheric static stability in midlatitudes and in the tropics. The arguments suggest an explanation for the observation that climatological isentropic slopes in midlatitudes are close to the critical slope required for baroclinic instability in a two-layer model.” Held, Issac M., 1982: On the Height of the Tropopause and the Static Stability of the Troposphere. J. Atmos. Sci., 39, 412–417. doi: http://dx.doi.org/10.1175/1520-0469(1982)0392.0.CO;2. [Full text]

Quasi-Biennial Variations in Temperature, Total Ozone, and Tropopause Height – Angell & Korshover (1964) “An analysis of mean-monthly temperature and total ozone data suggests that quasi-biennial oscillations extend to the temperate and polar latitudes of both hemispheres. Basically, there is symmetry with respect to the equator, although the oscillations show up most clearly in the Southern Hemisphere, and there is a tendency for the biennial maximum of temperature and total ozone to occur in the spring. Harmonic analysis implies a poleward drift of the biennial maximum of temperature and total ozone at a rate near 0.2 m sec−1, with the drift becoming indistinct poleward of 40°. The quasi-biennial variation in total ozone is very nearly in phase with the quasi-biennial variation in 50-mb temperature. There is also a quasi-biennial variation in tropopause height associated with the temperature oscillation in the lower stratosphere. There is weak evidence for a quasi-biennial variation in beryllium-7 in the lower stratosphere.” Angell, J. K., J. Korshover, 1964: Quasi-Biennial Variations in Temperature, Total Ozone, and Tropopause Height. J. Atmos. Sci., 21, 479–492. doi: http://dx.doi.org/10.1175/1520-0469(1964)0212.0.CO;2. [Full text]

Some ozone-weather relationships in the middle latitudes of the Southern Hemisphere – Kulkarni (1963) “
The paper discusses relationships observed between ozone and the upper-air measurements made at Brisbane, Aspendale and Macquarie Island. The correlation coefficients between the short-term fluctuations of ozone and the temperatures at 100, 200 and 300 mb levels at these places are presented. In general, high ozone was observed to be associated with the sinking of the tropopause, descending of stratospheric air, warming of the lower stratosphere and a southerly flow of air in the lower stratosphere. At Macquarie Island, an instance of the ozone fluctuations in the baroclinic waves of the polar night westerly vortex suggested that the middle stratospheric waves contributed to the unexplained long term variance in total ozone. The meteorological parameters at the 200 mb level did not reveal the type of oscillation shown by the spring maximum level of ozone with a periodicity of 24 months. From the study of the 60 mb temperatures, it is concluded that the middle stratospheric circulation is playing an important role in deciding the spring level of ozone in middle latitudes of the Southern Hemisphere.” R. N. Kulkarni, Quarterly Journal of the Royal Meteorological Society, Volume 89, Issue 382, pages 478–489, October 1963, DOI: 10.1002/qj.49708938205.

New research from early 2013

Since the end of the New research from last week series I have been noting new research papers in Twitter and in Facebook. For those who don’t follow those places, below are my new paper tweets since the beginning of 2013 to this day. There are 211 of them, which surprised me a little, because it’s almost 3 papers per day. I thought I would have averaged below 2 per day. So, here they are all mixed up (subject-wise, they actually are in temporal order so that latest is first):

1. Climate change is unlikely to dramatically reduce overall winter mortality rates http://onlinelibrary.wiley.com/doi/10.1002/wcc.211/abstract

2. Future grand solar minimum could slow down but not stop global warming http://onlinelibrary.wiley.com/doi/10.1002/grl.50361/abstract

3. More hurricanes to hit Western Europe due to global warming http://onlinelibrary.wiley.com/doi/10.1002/grl.50360/abstract

4. The stability of an evolving Atlantic meridional overturning circulation http://onlinelibrary.wiley.com/doi/10.1002/grl.50365/abstract

5. Recent intense hurricane response to global climate change (open access) http://link.springer.com/article/10.1007%2Fs00382-013-1713-0

6. Decades of observations are needed to determine cloud feedbacks http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00378.1

7. Over 21000 years old dissolved organic permafrost carbon was found in stream from Siberia http://onlinelibrary.wiley.com/doi/10.1002/grl.50348/abstract

8. Atlantic Multidecadal Oscillation’s structure and climate footprint http://link.springer.com/article/10.1007%2Fs00382-013-1712-1

9. Nonlinear effects of elevated temperature on grapevine phenology http://www.sciencedirect.com/science/article/pii/S016819231200295X

10. Has Northern Hemisphere been warming during the boreal winter of last few decades? http://www.sciencedirect.com/science/article/pii/S0921818113000672

11. Climate Impacts of a Large-Scale Biofuels Expansion http://onlinelibrary.wiley.com/doi/10.1002/grl.50352/abstract

12. Climate impact of stratospheric ozone recovery http://onlinelibrary.wiley.com/doi/10.1002/grl.50358/abstract

13. Potential for rooftop photovoltaics in Tokyo to replace nuclear capacity (open access) http://iopscience.iop.org/1748-9326/8/1/014042

14. Implications of a break-up of China for carbon dioxide emissions http://link.springer.com/article/10.1007%2Fs10584-013-0723-6

15. Parameterization of Wind Farms in Climate Models http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00376.1

16. The economic impact of climate change in the 20th and 21st centuries http://link.springer.com/article/10.1007%2Fs10584-012-0613-3

17. Tropical coral reef habitat in a geoengineered, high-CO2 world http://onlinelibrary.wiley.com/doi/10.1002/grl.50340/abstract

18. Extended season for northern butterflies http://link.springer.com/article/10.1007%2Fs00484-013-0649-8

19. Cold winter extremes in northern continents linked to Arctic sea ice loss (open access) http://iopscience.iop.org/1748-9326/8/1/014036

20. Recalculating GHG emissions saving of palm oil biodiesel (open access) http://link.springer.com/article/10.1007%2Fs10668-012-9387-z

21. Cosmic ray modulation of infra-red radiation in the atmosphere (only a small effect on climate) http://iopscience.iop.org/1748-9326/8/1/015026

22. Achieving Climate Change Absolute Accuracy in Orbit http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00149.1

23. Impacts of climate change on avian populations http://onlinelibrary.wiley.com/doi/10.1111/gcb.12195/abstract

24. On the origin of multidecadal to centennial Greenland temperature anomalies over the past 800 yr (open access) http://www.clim-past.net/9/583/2013/cp-9-583-2013.html

25. CMIP5 simulations might underestimate risk of prolonged droughts under climate change in western North America http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00732.1

26. Vertical structure of warming consistent with upward shift in middle and upper troposphere http://onlinelibrary.wiley.com/doi/10.1002/grl.50328/abstract

27. Anthropogenic climate change may directly influence ENSO http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00360.1

28. Important role for CO2 at past climate change transitions http://www.sciencedirect.com/science/article/pii/S0277379113000553

29. Vulnerability of calcifying larval stage of Antarctic sea urchin to ocean acidification and warming http://onlinelibrary.wiley.com/doi/10.1111/gcb.12190/abstract

30. High tolerance of microzooplankton to ocean acidification in an Arctic coastal plankton community (open access) http://www.biogeosciences.net/10/1471/2013/bg-10-1471-2013.html

31. Life histories predict coral community disassembly under multiple stressors http://onlinelibrary.wiley.com/doi/10.1111/gcb.12191/abstract

32. Shutdown and recovery of the AMOC in a coupled global climate model http://onlinelibrary.wiley.com/doi/10.1002/grl.50289/abstract

33. A new mechanism for Dansgaard-Oeschger cycles http://onlinelibrary.wiley.com/doi/10.1029/2012PA002364/abstract

34. CO2 plays a large role in observed temperature trend at Antarctic Peninsula’s Faraday/Vernadsky station http://onlinelibrary.wiley.com/doi/10.1002/grl.50301/abstract

35. When will the summer arctic be nearly sea ice free? http://onlinelibrary.wiley.com/doi/10.1002/grl.50316/abstract

36. Winter weather versus group thermoregulation: what determines survival in hibernating mammals? http://rd.springer.com/article/10.1007%2Fs00442-013-2612-0

37. Kilimanjaro likely to be ice-free before 2060 if current climatological conditions are maintained (open access) http://www.the-cryosphere.net/7/419/2013/tc-7-419-2013.html

38. Anthropogenic carbon dioxide source areas observed from space (open access) http://www.atmos-chem-phys.net/13/2445/2013/acp-13-2445-2013.html

39. Climate change reduces the net sink of CH4 and N2O in a semiarid grassland http://onlinelibrary.wiley.com/doi/10.1111/gcb.12182/abstract

40. Vulnerability of Terrestrial Island Vertebrates to Projected Sea-Level Rise http://onlinelibrary.wiley.com/doi/10.1111/gcb.12185/abstract

41. Southeastern U.S. anomalous cooling in the 20th century http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00559.1

42. Anthropogenic effects on the subtropical jet in the Southern Hemisphere (open access) http://iopscience.iop.org/1748-9326/8/1/014030

43. Effect of cloudiness on long-term variability in air temperature in Krakow http://onlinelibrary.wiley.com/doi/10.1002/joc.3672/abstract

44. Improved ice bed, surface and thickness datasets for Antarctica (open access) http://www.the-cryosphere.net/7/375/2013/tc-7-375-2013.html

45. Climate Change Impacts on Global Agricultural Water Deficit http://onlinelibrary.wiley.com/doi/10.1002/grl.50279/abstract

46. Observed trends in the global jet stream characteristics during the second half of the 20th century http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50305/abstract

47. There truly are mushroom clouds (open access) http://iopscience.iop.org/1748-9326/8/1/014029

48. Analysis of global methane changes after the 1991 Pinatubo volcanic eruption (open access) http://www.atmos-chem-phys.net/13/2267/2013/acp-13-2267-2013.html

49. Icelandic ice caps contribute to sea level rise too http://onlinelibrary.wiley.com/doi/10.1002/grl.50278/abstract

50. Human-induced changes to atmospheric composition affects global mean surface temperature changes http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50296/abstract

51. Detection and attribution of anthropogenic climate change impacts http://onlinelibrary.wiley.com/doi/10.1002/wcc.209/abstract

52. Australian Great Flood of 1954: Estimating the cost of a similar event in 2011 http://journals.ametsoc.org/doi/abs/10.1175/WCAS-D-12-00018.1

53. Impacts of global warming on Northern Hemisphere winter storm tracks http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50286/abstract

54. Sea ice loss is weakening the oceanic CO2 sink in Canada Basin http://onlinelibrary.wiley.com/doi/10.1002/grl.50268/abstract

55. Anthropogenic influence is clearly detectable in extreme temperatures over China http://onlinelibrary.wiley.com/doi/10.1002/grl.50285/abstract

56. Evolution of the subglacial drainage system beneath the Greenland Ice Sheet revealed by tracers http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1737.html

57. Mass loss of Greenland’s glaciers and ice caps 2003-2008 http://onlinelibrary.wiley.com/doi/10.1002/grl.50270/abstract

58. Vegetation-related roughness is possible cause of recent decrease in dust emission from Sahel http://onlinelibrary.wiley.com/doi/10.1002/grl.50273/abstract

59. Global wind power resource estimates might be substantially overstated (open access) http://iopscience.iop.org/1748-9326/8/1/015021

60. Invitation for researchers to study information stored in cave ice deposits before they melt away http://www.sciencedirect.com/science/article/pii/S0277379113000176

61. No cumulative effect of 10 years of elevated CO2 on perennial plant biomass components in Mojave Desert http://onlinelibrary.wiley.com/doi/10.1111/gcb.12177/abstract

62. Diagnosing Present and Future Permafrost from Climate Models http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00341.1

63. Irreversible mass loss of Canadian Arctic Archipelago glaciers http://onlinelibrary.wiley.com/doi/10.1002/grl.50214/abstract

64. Potential for evolutionary responses to climate change – evidence from tree populations http://onlinelibrary.wiley.com/doi/10.1111/gcb.12181/abstract

65. Projected Changes in East African Rainy Seasons http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00455.1

66. NDVI data for 1982–2006 indicates CO2 fertilization effect in global vegetation http://onlinelibrary.wiley.com/doi/10.1002/gbc.20027/abstract

67. Surface elevation and velocity changes on the south-central Greenland ice sheet: 1980-2011 http://www.ingentaconnect.com/content/igsoc/jog/2012/00000058/00000212/art00015

68. Accelerating shrinkage of Patagonian glaciers from the Little Ice Age http://www.ingentaconnect.com/content/igsoc/jog/2012/00000058/00000212/art00004

69. From this abstract I can’t tell if there will be more suitable or unsuitable panda habitat but I’m guessing latter http://onlinelibrary.wiley.com/doi/10.1002/met.1376/abstract

70. Warm-season severe wind events in Germany http://www.sciencedirect.com/science/article/pii/S0169809512002530

71. Extreme hail day climatology in Southwestern France http://www.sciencedirect.com/science/article/pii/S016980951200333X

72. New generation of climate models agree better with observations http://onlinelibrary.wiley.com/doi/10.1002/grl.50256/abstract

73. Space–time distribution of tornado events in Bulgaria (1956–2010) http://www.sciencedirect.com/science/article/pii/S0169809512002281

74. Impacts of ocean acidification on marine organisms http://onlinelibrary.wiley.com/doi/10.1111/gcb.12179/abstract

75. Snow variability in Romania in connection to large-scale atmospheric circulation http://onlinelibrary.wiley.com/doi/10.1002/joc.3671/abstract

76. Severe thunderstorms and climate change http://www.sciencedirect.com/science/article/pii/S0169809512000968

77. Permafrost soils – initial carbon sink but eventually possible carbon source (open access) http://iopscience.iop.org/1748-9326/8/1/014026

78. The upper end of climate model temperature projections is inconsistent with past warming (open access) http://iopscience.iop.org/1748-9326/8/1/014024

79. Synchronous fluctuations of glaciers in the Alps and Altai in the second half of the Holocene http://hol.sagepub.com/content/early/2013/02/18/0959683612475143.abstract

80. The contribution of radiative feedbacks to orbitally-driven climate change http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00419.1

81. Likely Ranges of Climate Change in Bolivia http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-12-0224.1

82. Strong increase in convective precipitation in response to higher temperatures http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1731.html

83. Predator-induced reduction of freshwater carbon dioxide emissions http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1734.html

84. Rapid climatic driven shifts of diatoms at high latitudes http://www.sciencedirect.com/science/article/pii/S0034425713000266

85. Modelled Rapid Adjustments in Diurnal Temperature Range Response to CO2 and Solar Forcings http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50243/abstract

86. The strength of the holiday effect is mainly caused by the degree of urbanization http://www.sciencedirect.com/science/article/pii/S1352231013000198

87. In addition to warming and acidification, mankind also does other bad things to coral reefs http://www.sciencedirect.com/science/article/pii/S0967064513000714

88. Global precipitation trends: larger than expected increase over oceans, over land trends are what IPCC AR4 says http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50212/abstract

89. Storm intensity has increased in San Francisco Bay Area between 1890 and 2010 http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50225/abstract

90. Anthropogenic Impact on Agulhas Leakage http://onlinelibrary.wiley.com/doi/10.1002/grl.50243/abstract

91. Global nutrient limitation in terrestrial vegetation http://onlinelibrary.wiley.com/doi/10.1029/2011GB004252/abstract

92. Climate warming shifts carbon allocation from stemwood to roots in calcium-depleted spruce forests http://onlinelibrary.wiley.com/doi/10.1029/2011GB004268/abstract

93. Vietnam has warmed about twice the rate of global warming since 1970′s http://onlinelibrary.wiley.com/doi/10.1002/joc.3684/abstract

94. Why was there an increase in carbon-14 production in AD 774-775? http://onlinelibrary.wiley.com/doi/10.1002/grl.50222/abstract

95. A new global reconstruction of temperature changes at the Last Glacial Maximum (open access) http://www.clim-past.net/9/367/2013/cp-9-367-2013.html

96. A review of sea ice proxy information from polar ice cores http://www.sciencedirect.com/science/article/pii/S0277379113000206

97. Optimal fingerprinting finds the effect of anthropogenic forcings including land use in daily extreme temperatures http://onlinelibrary.wiley.com/doi/10.1002/grl.50159/abstract

98. Anthropogenic influences have made substantial contribution to evolution of free atmosphere temperatures http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50255/abstract

99. Yet another attribution study shows anthropogenic GHG’s dominating global warming since mid 20th century http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50239/abstract

100. Human-induced climate change was one of the causes of 2011 East African drought http://onlinelibrary.wiley.com/doi/10.1002/grl.50235/abstract

101. Arctic sea ice cover may have passed a tipping point in 2007 (open access) http://www.the-cryosphere.net/7/275/2013/tc-7-275-2013.html

102. Loss of plant biodiversity eliminates stimulatory effect of elevated CO2 on earthworm activity in grasslands http://rd.springer.com/article/10.1007%2Fs00442-012-2585-4

103. Artificial light pollution: are shifting spectral signatures changing the balance of species interactions? http://onlinelibrary.wiley.com/doi/10.1111/gcb.12166/abstract

104. Detrimental effects of Ocean Acidification on the economically important Mediterranean red coral http://onlinelibrary.wiley.com/doi/10.1111/gcb.12171/abstract

105. Distribution of ant species shifts to higher elevations with minimum temperature increase http://onlinelibrary.wiley.com/doi/10.1111/gcb.12169/abstract

106. CO2 stimulation has not been enough to counteract warming induced drought stress in Mexican high altitude forests http://onlinelibrary.wiley.com/doi/10.1111/gcb.12170/abstract

107. Modes and Mechanisms of Global Water Vapor Variability over the 20th Century http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00585.1

108. The transient versus the equilibrium response of sea ice to global warming http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00492.1

109. Antarctic ozone loss in 1979–2010: first sign of ozone recovery (open access) http://www.atmos-chem-phys.net/13/1625/2013/acp-13-1625-2013.html

110. Accelerated glacier melt in 2002 – 2007 over the Bering Glacier in Alaska http://www.sciencedirect.com/science/article/pii/S0034425713000199

111. Ice cores from Antarctica and Greenland improve our knowledge of volcanic forcing over last 2000 years http://onlinelibrary.wiley.com/doi/10.1029/2012JD018603/abstract

112. Spatial distribution of temperature trends in Sicily http://onlinelibrary.wiley.com/doi/10.1002/joc.3657/abstract

113. New shaving technique to release trapped air for measurements from ice core samples http://www.atmos-meas-tech.net/6/251/2013/amt-6-251-2013.html

114. Important role of mid-tropospheric atmospheric circulation in recent surface melt increase over Greenland http://www.the-cryosphere.net/7/241/2013/tc-7-241-2013.html

115. Controls of Global Snow Under a Changed Climate http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00528.1

116. How much land based GHG can be achieved without compromising food security and environmental goals? http://onlinelibrary.wiley.com/doi/10.1111/gcb.12160/abstract

117. Dansgaard–Oeschger events: bifurcation points in the climate system (open access) http://www.clim-past.net/9/323/2013/cp-9-323-2013.html

118. Ocean acidification and warming scenarios increase microbioerosion of coral skeletons http://onlinelibrary.wiley.com/doi/10.1111/gcb.12158/abstract

119. The Medieval Climate Anomaly and the Little Ice Age in the eastern Ecuadorian Andes (open access) http://www.clim-past.net/9/307/2013/cp-9-307-2013.html

120. Ice sheet sources of sea level rise and freshwater discharge during the last deglaciation http://onlinelibrary.wiley.com/doi/10.1029/2011RG000371/abstract

121. Surface albedo feedbacks from climate variability and change http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50230/abstract

122. Stratospheric ozone depletion has contributed to Hadley cell expansion http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50232/abstract

123. Snow variability in the Swiss Alps 1864–2009 http://onlinelibrary.wiley.com/doi/10.1002/joc.3653/abstract

124. Using phenology to assess urban heat islands in tropical and temperate regions http://onlinelibrary.wiley.com/doi/10.1002/joc.3651/abstract

125. Quaternary history of sea ice in the western Arctic Ocean based on foraminifera http://www.sciencedirect.com/science/article/pii/S027737911300005X

126. What would super eruption of the Yellowstone volcanic system do to global climate and carbon cycle (open access) http://www.biogeosciences.net/10/669/2013/bg-10-669-2013.html

127. Arctic microbial community dynamics influenced by elevated CO2 levels (open access) http://www.biogeosciences.net/10/719/2013/bg-10-719-2013.html

128. Interhemispheric temperature asymmetry over the 20th century and in future projections http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00525.1

129. Relationship between Winter Sea Ice and Summer Atmospheric Circulation over Eurasia http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00524.1

130. How wind farms affect local weather http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-12-00185.1

131. Past history and future fate of Arctic small mammals in a changing climate http://onlinelibrary.wiley.com/doi/10.1111/gcb.12157/abstract

132. Greenland meltwater lakes have expanded substantially inland to higher elevations with warming http://www.the-cryosphere.net/7/201/2013/tc-7-201-2013.html

133. Ocean acidification effects on Arctic microbial community dynamics (open access) http://www.biogeosciences.net/10/719/2013/bg-10-719-2013.html

134. Environmental controls on the thermal structure of alpine glaciers (open access) http://www.the-cryosphere.net/7/167/2013/tc-7-167-2013.html

135. A 2°C warmer world is not safe for ecosystem services in the European Alps http://onlinelibrary.wiley.com/doi/10.1111/gcb.12156/abstract

136. A synthesis and review of Holocene paleofire records and their controls http://www.sciencedirect.com/science/article/pii/S0277379112005318

137. Predictability of twentieth century sea-level rise from past data http://iopscience.iop.org/1748-9326/8/1/014013

138. Anthropogenic changes in the dynamics of the mesosphere http://onlinelibrary.wiley.com/doi/10.1002/grl.50158/abstract

139. Global shifts towards positive species interactions with increasing environmental stress http://onlinelibrary.wiley.com/doi/10.1111/ele.12080/abstract

140. Reconstruction of northeast Asia spring temperature 1784–1990 (open access) http://www.clim-past.net/9/261/2013/cp-9-261-2013.html

141. Can black carbon in snow be detected by remote sensing? Not likely, says a new study http://onlinelibrary.wiley.com/doi/10.1029/2012JD018476/abstract

142. Increased summer rainfall in northwest Australia linked to southern Indian Ocean climate variability http://onlinelibrary.wiley.com/doi/10.1029/2012JD018323/abstract

143. Quantifying the effect of urbanization on U.S. Historical Climatology Network temperature records http://onlinelibrary.wiley.com/doi/10.1029/2012JD018509/abstract

144. Quantification of methane emission rates from coal mine ventilation shafts http://www.atmos-meas-tech.net/6/151/2013/amt-6-151-2013.html

145. An estimate of global glacier volume http://www.the-cryosphere.net/7/141/2013/tc-7-141-2013.html

146. Global river discharge and water temperature under climate change http://www.sciencedirect.com/science/article/pii/S0959378012001331

147. Detectable Changes in the Frequency of Temperature Extremes http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00678.1

148. An assessment of the Atlantic and Arctic sea–air CO2 fluxes, 1990–2009 (open access) http://www.biogeosciences.net/10/607/2013/bg-10-607-2013.html

149. How will climate change modify river flow regimes in Europe? http://www.hydrol-earth-syst-sci.net/17/325/2013/hess-17-325-2013.html

150. CryoSat-2 estimates of Arctic sea ice thickness and volume http://onlinelibrary.wiley.com/doi/10.1002/grl.50193/abstract

151. Climate change is expected to decrease C4 crop yields in Africa and India by 2100 http://www.sciencedirect.com/science/article/pii/S0168192311003406

152. The impact of an intense summer cyclone on 2012 Arctic sea ice retreat http://onlinelibrary.wiley.com/doi/10.1002/grl.50190/abstract

153. Arctic climate warming and sea ice declines lead to increased storm surge activity http://onlinelibrary.wiley.com/doi/10.1002/grl.50191/abstract

154. CO2 forcing decreases maximum strength of the Atlantic meridional overturning circulation http://onlinelibrary.wiley.com/doi/10.1002/grl.50183/abstract

155. Simultaneous shifts in temperature in Central Europe and Greenland during the last deglaciation http://onlinelibrary.wiley.com/doi/10.1002/grl.50181/abstract

156. Global hot-spots of heat stress on agricultural crops due to climate change http://www.sciencedirect.com/science/article/pii/S0168192311002784

157. Estimating impacts of warming temperatures on California’s electricity system http://www.sciencedirect.com/science/article/pii/S0959378012001458

158. Staying cool in a changing climate http://www.sciencedirect.com/science/article/pii/S0959378013000022

159. Where do winds come from? (open access) http://www.atmos-chem-phys.net/13/1039/2013/acp-13-1039-2013.html

160. The carbon budget of South Asia (open access) http://www.biogeosciences.net/10/513/2013/bg-10-513-2013.html

161. Does Antarctic glaciation cool the world? (open access) http://www.clim-past.net/9/173/2013/cp-9-173-2013.htm

162. Short-term weather and belief in anthropogenic climate change http://journals.ametsoc.org/doi/abs/10.1175/WCAS-D-12-00048.1

163. Updated analyses of temperature and precipitation extreme indices since the beginning of 20th century http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50150/abstract

164. Current state of glaciers in the tropical Andes (open access) http://www.the-cryosphere.net/7/81/2013/tc-7-81-2013.html

165. Decadal record of satellite carbon monoxide observations (open access) http://www.atmos-chem-phys.net/13/837/2013/acp-13-837-2013.html

166. Dessler’s 2010 results of positive short-term cloud feedback seem to be robust http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50199/abstract

167. A 600,000 year Arctic sea-ice record from Mendeleev Ridge based on ostracodes http://www.sciencedirect.com/science/article/pii/S0277379112005380

168. Revised estimates of Greenland ice sheet thinning histories based on ice-core records http://www.sciencedirect.com/science/article/pii/S027737911200532X

169. Change in snow phenology and its potential feedback to temperature in the Northern Hemisphere (open access) http://iopscience.iop.org/1748-9326/8/1/014008

170. The Suess effect in Fiji coral carbon-13 and its potential as a tracer of anthropogenic CO2 uptake http://www.sciencedirect.com/science/article/pii/S0031018212006505

171. Evidence of current impact of climate change on life http://onlinelibrary.wiley.com/doi/10.1111/gcb.12143/abstract

172. Trends in ISCCP, MISR and MODIS Cloud-Top-Height and Optical-Depth Histograms http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50207/abstract

173. Changepoint Detection in Climatic Time Series with Long-term Trends http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00704.1

174. Elevated emissions from high-latitude wetlands contributed to early Holocene high CH4 concentration http://onlinelibrary.wiley.com/doi/10.1002/gbc.20025/abstract

175. High predictive skill of global surface temperature a year ahead http://onlinelibrary.wiley.com/doi/10.1002/grl.50169/abstract

176. Improving the temporal and spatial distribution of CO2 emissions from global fossil fuel emission data sets http://onlinelibrary.wiley.com/doi/10.1029/2012JD018196/abstract

177. The Roles of Aerosol Direct and Indirect Effects in Past and Future Climate Change http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50192/abstract

178. Land water contribution to sea level from GRACE and Jason measurements http://onlinelibrary.wiley.com/doi/10.1002/jgrc.20058/abstract

179. Influence of climate variability on seasonal extremes over Australia http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50164/abstract

180. Arctic climate sensitivity to local black carbon http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50176/abstract

181. Increased variability in cold-season temperature since the 1930s in subtropical China http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00332.1

182. Assessment of global cloud datasets from satellites http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-12-00117

183. Cloud and water vapor feedbacks are still biased in CMIP5 models http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00575.1

184. No divergence in a 1200 year tree-ring temperature reconstruction at the northern European treeline http://bit.ly/10l8R1h

185. Clouds become fewer, higher, and thicker, and net cloud feedback is positive in most CMIP5 models http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00555.1

186. An analysis of the short-term cloud feedback using MODIS data http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00547.1

187. On the use of elevation, altitude, and height in the ecological and climatological literature http://rd.springer.com/article/10.1007%2Fs00442-012-2416-7

188. Global all-sky shortwave direct radiative forcing of anthropogenic aerosols http://onlinelibrary.wiley.com/doi/10.1029/2012JD018294/abstract

189. Global analysis of night marine air temperature and its uncertainty since 1880 http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50152/abstract

190. Sea surface temperature was lower than today during Medieval Warm Period in Southern Adriatic Sea region http://hol.sagepub.com/content/early/2013/01/17/0959683612467482.abstract

191. Global warming in an independent record of the past 130 years http://onlinelibrary.wiley.com/doi/10.1029/2012GL054271/abstract

192. High emission of carbon dioxide and methane during ice-thaw in high latitude lakes http://onlinelibrary.wiley.com/doi/10.1002/grl.50152/abstract

193. There is high probability for black carbon emissions to have positive forcing and warm the climate http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50171/abstract

194. Climatic impact of Changbaishan volcano eruption in 10th century might have been only regional http://onlinelibrary.wiley.com/doi/10.1029/2012GL054246/abstract

195. 20th Century summer sunshine levels possibly similar to the Mediæval period in Swedish reconstruction http://www.sciencedirect.com/science/article/pii/S0277379112004854

196. Summer 1540 might have been warmer in Switzerland than summer 2003 (open access) http://www.clim-past.net/9/41/2013/cp-9-41-2013.html

197. Site factors and tree age can be more important drivers of growth trends in arctic treelines than climate http://www.sciencedirect.com/science/article/pii/S1125786512000768

198. In contrast to northern Europe the YD event had no major effect on mammals in Switzerland http://www.sciencedirect.com/science/article/pii/S0031018212006943

199. Soil warming increases alpine plant species richness but decreases germination from soil seed bank http://onlinelibrary.wiley.com/doi/10.1111/gcb.12135/abstract

200. Fragmentation and climate warming interact to affect persistence of native trout in the Colorado River basin http://onlinelibrary.wiley.com/doi/10.1111/gcb.12136/abstract

201. Fossil plants used for CO2 reconstruction from Late Oligocene to Early Miocene http://www.sciencedirect.com/science/article/pii/S0031018213000047

202. Global anthropogenic sulfur dioxide emissions 2000-2011 (open access) http://iopscience.iop.org/1748-9326/8/1/014003

203. Roe deer in forest habitats cannot currently cope with increasingly early springs http://onlinelibrary.wiley.com/doi/10.1111/ele.12059/abstract

204. In Arctic, local black carbon causes cooling while remote black carbon causes warming (open access) http://www.atmos-chem-phys.net/13/211/2013/acp-13-211-2013.html

205. Enhanced flooding due climate change can result in rapid emissions of stored carbon in soils http://onlinelibrary.wiley.com/doi/10.1029/2012GL054145/abstract

206. Expected decrease of tropical cyclones in Southern Gulf of Mexico/Caribbean and increase over central Atlantic http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00342.1

207. Observations and models agree on temperature trends in Southern Hemisphere stratosphere http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50126/abstract

208. Analysis of temperature extremes in Australia from 1910 to 2010 http://onlinelibrary.wiley.com/doi/10.1002/grl.50132/abstract

209. Are climate model simulations of clouds improving? http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50141/abstract

210. Early Holocene summer temperatures may have been 2.3°C above modern ones in Swedish Scandes http://onlinelibrary.wiley.com/doi/10.1111/bor.12003/abstract

211. Changes in soil biotic activity might make Arctic substantial carbon source and Antarctica a carbon sink http://onlinelibrary.wiley.com/doi/10.1111/ele.12058/abstract

Papers on snow cover changes

This is a list of papers on snow cover changes with an emphasis on hemispheric and global observational analyses. The list is not complete, and will most likely be updated in future in order to make it more thorough and more representative.

Change in snow phenology and its potential feedback to temperature in the Northern Hemisphere over the last three decades – Peng et al. (2013) “Trends in the duration or extent of snow cover are expected to feedback to temperature trends. We analyzed trends in dates of onset and termination of snow cover in relation to temperature over the past 27 years (1980–2006) from over 636 meteorological stations in the Northern Hemisphere. Different trends in snow duration are observed over North America and Eurasia. Over North America, the termination date of snow cover remained stable during the 27 years, whereas over Eurasia it has advanced by 2.6 ± 5.6 d decade⁻¹. Earlier snow cover termination is systematically correlated on a year-to-year basis with a positive temperature anomaly during the snowmelt month with a sensitivity of −0.077 °C d⁻¹. These snow feedbacks to air temperature are more important in spring, because high net radiation is coupled with thin snow cover. Shushi Peng et al 2013 Environ. Res. Lett. 8 014008 doi:10.1088/1748-9326/8/1/014008. [Full text]

Northern Hemisphere spring snow cover variability and change over 1922–2010 including an assessment of uncertainty – Brown & Robinson (2011) “An update is provided of Northern Hemisphere (NH) spring (March, April) snow cover extent (SCE) over the 1922–2010 period incorporating the new climate data record (CDR) version of the NOAA weekly SCE dataset, with annual 95% confidence intervals estimated from regression analysis and intercomparison of multiple datasets. The uncertainty analysis indicates a 95% confidence interval in NH spring SCE of ±5–10% over the pre-satellite period and ±3–5% over the satellite era. The multi-dataset analysis shows larger uncertainties monitoring spring SCE over Eurasia (EUR) than North America (NA) due to the more complex regional character of the snow cover variability and larger between-dataset variability over northern Europe and north-central Russia. Trend analysis of the updated SCE series provides evidence that NH spring snow cover extent has undergone significant reductions over the past ~90 yr and that the rate of decrease has accelerated over the past 40 yr. The rate of decrease in March and April NH SCE over the 1970–2010 period is ~0.8 million km² per decade corresponding to a 7% and 11% decrease in NH March and April SCE respectively from pre-1970 values. In March, most of the change is being driven by Eurasia (NA trends are not significant) but both continents exhibit significant SCE reductions in April. The observed trends in SCE are being mainly driven by warmer air temperatures, with NH mid-latitude air temperatures explaining ~50% of the variance in NH spring snow cover over the 89-yr period analyzed. However, there is also evidence that changes in atmospheric circulation around 1980 involving the North Atlantic Oscillation and Scandinavian pattern have contributed to reductions in March SCE over Eurasia. Brown, R. D. and Robinson, D. A.: Northern Hemisphere spring snow cover variability and change over 1922–2010 including an assessment of uncertainty, The Cryosphere, 5, 219-229, doi:10.5194/tc-5-219-2011, 2011. [Full text]

Long-term variability in Northern Hemisphere snow cover and associations with warmer winters – McCabe & Wolock (2010) “A monthly snow accumulation and melt model is used with gridded monthly temperature and precipitation data for the Northern Hemisphere to generate time series of March snow-covered area (SCA) for the period 1905 through 2002. The time series of estimated SCA for March is verified by comparison with previously published time series of SCA for the Northern Hemisphere. The time series of estimated Northern Hemisphere March SCA shows a substantial decrease since about 1970, and this decrease corresponds to an increase in mean winter Northern Hemisphere temperature. The increase in winter temperature has caused a decrease in the fraction of precipitation that occurs as snow and an increase in snowmelt for some parts of the Northern Hemisphere, particularly the mid-latitudes, thus reducing snow packs and March SCA. In addition, the increase in winter temperature and the decreases in SCA appear to be associated with a contraction of the circumpolar vortex and a poleward movement of storm tracks, resulting in decreased precipitation (and snow) in the low- to mid-latitudes and an increase in precipitation (and snow) in high latitudes. If Northern Hemisphere winter temperatures continue to warm as they have since the 1970s, then March SCA will likely continue to decrease. Gregory J. McCabe, David M. Wolock, Climatic Change, March 2010, Volume 99, Issue 1-2, pp 141-153, DOI: 10.1007/s10584-009-9675-2.

Changing Northern Hemisphere Snow Seasons – Choi et al. (2010) “Spatial and temporal patterns in the onset, offset, and length of the snow season across Northern Hemisphere continents are examined for the period from 1967 to 2008. Full snow seasons (FSS) and core snow seasons (CSS) are defined based on the consistency of snow cover within a location over the course of the cold season. Climatologically, the seasonal onsets of FSS and CSS progress more rapidly across the continents than the slower spring northward offset. Average Northern Hemisphere FSS duration has decreased at a rate of 0.8 week decade⁻¹ (5.3 days decade⁻¹) between the winters of 1972/73 and 2007/08, while there is no significant hemispheric change in CSS duration. Changes in the FSS duration are attributed primarily to a progressively earlier offset, which has advanced poleward at a rate of 5.5 days decade⁻¹. A major change in the trends of FSS offset and duration occurred in the late 1980s. Earlier FSS offsets, ranging from 5 to 25 days, and resultant abbreviated durations are observed in western Europe, central and East Asia, and the mountainous western United States. Where regional changes in CSS were observed, most commonly there were shifts in both onset and offset dates toward earlier dates. Results indicate that it is important to pay close attention to spring snowmelt as an indicator of hemispheric climate variability and change. Choi, Gwangyong, David A. Robinson, Sinkyu Kang, 2010: Changing Northern Hemisphere Snow Seasons. J. Climate, 23, 5305–5310. doi: http://dx.doi.org/10.1175/2010JCLI3644.1. [Full text]

Recent Northern Hemisphere snow cover extent trends and implications for the snow-albedo feedback – Déry & Brown (2007) “Monotonic trend analysis of Northern Hemisphere snow cover extent (SCE) over the period 1972–2006 with the Mann-Kendall test reveals significant declines in SCE during spring over North America and Eurasia, with lesser declines during winter and some increases in fall SCE. The weekly mean trend attains −1.28, −0.78, and −0.48 × 10⁶ km² (35 years)⁻¹ over the Northern Hemisphere, North America, and Eurasia, respectively. The standardized SCE time series vary and trend coherently over Eurasia and North America, with evidence of a poleward amplification of decreasing SCE trends during spring. Multiple linear regression analyses reveal a significant dependence of the retreat of the spring continental SCE on latitude and elevation. The poleward amplification is consistent with an enhanced snow-albedo feedback over northern latitudes that acts to reinforce an initial anomaly in the cryospheric system. Stephen J. Déry, Ross D. Brown, Geophysical Research Letters, Volume 34, Issue 22, November 2007, DOI: 10.1029/2007GL031474. [Full text]

Variability and trends in the annual snow-cover cycle in Northern Hemisphere land areas, 1972–2000 – Dye (2002) “This study investigated variability and trends in the annual snow-cover cycle in regions covering high-latitude and high-elevation land areas in the Northern Hemisphere. The annual snow-cover cycle was examined with respect to the week of the last-observed snow cover in spring (WLS), the week of the first-observed snow cover in autumn (WFS), and the duration of the snow-free period (DSF). The analysis used a 29-year time-series (1972–2000) of weekly, visible-band satellite observations of Northern Hemisphere snow cover from NOAA with corrections applied by D. Robinson of Rutgers University Climate Laboratory. Substantial interannual variability was observed in WLS, WFS and DSF (standard deviations of 0·8–1·1, 0·7–0·9 and 1·0–1·4 weeks, respectively), which is related directly to interannual variability in snow-cover area in the regions and time periods of snow-cover transition. Over the nearly three-decade study period, WLS shifted earlier by 3–5 days/decade as determined by linear regression analysis. The observed shifts in the annual snow-cover cycle underlie a significant trend toward a longer annual snow-free period. The DSF increased by 5–6 days/decade over the study period, primarily as a result of earlier snow cover disappearance in spring. The observed trends are consistent with reported trends in the timing and length of the active growing season as determined from satellite observations of vegetation greenness and the atmospheric CO₂ record. Dennis G. Dye, Hydrological Processes, Volume 16, Issue 15, pages 3065–3077, 30 October 2002, DOI: 10.1002/hyp.1089.

Northern Hemisphere Snow Cover Variability and Change, 1915–97 – Brown (2000) “Historical and reconstructed snow cover data from stations in Canada, the United States, the former Soviet Union, and the People’s Republic of China were used to reconstruct monthly snow cover extent (SCE) fluctuations over midlatitudinal (40°–60°N) regions of North America (NA) and Eurasia back to the early 1900s using an areal snow index approach. The station distribution over NA allowed SCE to be reconstructed back to 1915 for 6 months (November–April), along with estimates of monthly mean snow water equivalent (SWE) from gridded daily snow depth data. Over Eurasia, SCE was able to be reconstructed back to 1922, but major gaps in the station network limited the approach to 3 months (October, March, and April). The reconstruction provided evidence of a general twentieth century increase in NA SCE, with significant increases in winter (December–February) SWE averaging 3.9% per decade. The results are consistent with an observed increasing trend in winter snow depth over Russia and provide further evidence for systematic increases in precipitation over NH midlatitudes. North American spring snow cover was characterized by rapid decreases during the 1980s and early 1990s with a significant long-term decrease in April SWE averaging 4.4% per decade. Eurasia was characterized by a significant reduction in April SCE over the 1922–97 period associated with a significant spring warming. The snow cover reduction was significant at the hemispheric scale with an estimated average NH SCE loss of 3.1 × 10⁶ km² (100 yr)⁻¹ associated with significant warming of 1.26°C (100 yr)⁻¹ over NH midlatitudinal land areas (40°–60°N). The computed temperature sensitivity of NH April SCE was −2.04 × 10⁶ km² °C⁻¹. Since 1950, March SCE decreases have become more important than those in April with significant reductions over both continents averaging 8.5 × 10⁶ km² (100 yr)⁻¹. March was also observed to have experienced the largest warming during the November–April snow season with significant post-1950 warming trends in both continents averaging 4.1°C (100 yr)⁻¹. The hemisphere-wide elevated March snow cover–temperature response is consistent with the position of the snowline over continental grassland vegetation zones where snow cover is relatively shallow and the potential snow cover area–albedo feedback is large.” Brown, Ross D., 2000: Northern Hemisphere Snow Cover Variability and Change, 1915–97. J. Climate, 13, 2339–2355. doi: http://dx.doi.org/10.1175/1520-0442(2000)0132.0.CO;2. [Full text]

Northern Hemisphere snow extent: regional variability 1972–1994 – Frei & Robinson (1999) “Snow cover is an important hydrologic and climatic variable due to its effects on water supplies, and on energy and mass exchanges at the surface. We investigate the kinematics and climatology of Northern Hemisphere snow extent between 1972 and 1994, and associated circulation patterns. Interannual fluctuations of North American and Eurasian snow extents are driven by both hemispheric scale signals, as well as signals from smaller ‘coherent’ regions, within which interannual fluctuations of snow extent are highly correlated. These regions cover only 2–6% of the continental land area north of 20°N, yet during many months they explain more than 60% of the variance in continental snow extent. They are identified using Principal Components Analysis (PCA) of digitized snow extent charts obtained from the National Oceanic and Atmospheric Administration (NOAA). Significant month-to-month persistence is found over western North America and Europe during winter and spring. Geographically and seasonally dependent associations are identified between North American snow extent and atmospheric circulation patterns, surface air temperature, and snowfall. Over western North America, snow extent is associated with the longitudinal position of the North American ridge. Over eastern North America, snow extent is associated with a meridional oscillation in the 500-mb geopotential height field. These teleconnection patterns, derived using composite analyses, are associated with secondary modes of tropospheric variability during autumn and winter. During spring, snow extent becomes effectively decoupled from tropospheric dynamics. These results are useful for understanding the natural variability of the climate system, reconstructing pre-satellite era climate variability, evaluating climate models, and detecting climate change. Allan Frei, David A. Robinson, International Journal of Climatology, Volume 19, Issue 14, pages 1535–1560, 30 November 1999, DOI: 10.1002/(SICI)1097-0088(19991130)19:143.0.CO;2-J. [Full text]

Recent variations and regional relationships in Northern Hemisphere snow cover – Robinson et al. (1995) Abstract doesn’t seem to be available online. Robinson, David A.; Frei, Allan; Serreze, Mark C., Annals of Glaciology, vol.21, pp.71-76.

Changes of Snow Cover, Temperature, and Radiative Heat Balance over the Northern Hemisphere – Groisman et al. (1994) “Contemporary large-scale changes in satellite-derived snow cover were examined over the Northern Hemisphere extratropical land (NEL) areas. These areas encompass 55% of the land in the Northern Hemisphere. Snow cover (S) transient regions, the “centers of action” relative to interannual variations of snow cover, were identified for the years 1972–1992. During these years a global retreat in snow cover extent (SE) occurred in the second half of the hydrologic year (April–September). Mean annual SE has decreased by 10% (2.3 × 10⁶ km²). Negative trends account for one-third to one-half of the interannual continental variance of SE. The historical influence of S on the planetary albedo and outgoing longwave radiation (OLR) is investigated. The mean annual response of the S feedback on the radiative balance (RB) is negative and suggests a large-scale heat redistribution. During autumn and early winter (up to January), however, the feedback of S on the planetary RB may he positive. Only by February does the cooling effect of S (due to albedo increase) dominate the planetary warming due to reduced OLR over the S. Despite a wintertime maximum in SF, the feedback in spring has the greatest magnitude. The global retreat of spring SE should lead to a positive feedback on temperature. Based on observed records of S, changes in RB are calculated that parallel an observed increase of spring temperature during the past 20 years. The results provide a partial explanation of the significant increase in spring surface air temperature observed over the land areas of the Northern Hemisphere during the past century. The mean SE in years with an El Niño and La Niña were also evaluated. El Niño events are generally accompanied by increased SE over the NEL during the first half of the hydrological year. In the second half of the hydrologic year (spring and summer), the El Niño events are accompanied by a global retreat of SE. Groisman, Pavel Ya, Thomas R. Karl, Richard W. Knight, Georgiy L. Stenchikov, 1994: Changes of Snow Cover, Temperature, and Radiative Heat Balance over the Northern Hemisphere. J. Climate, 7, 1633–1656. doi: http://dx.doi.org/10.1175/1520-0442(1994)0072.0.CO;2. [Full text]

Global Snow Cover Monitoring: An Update – Robinson et al. (1993) “Accurate monitoring of the large-scale dimensions of global snow cover is essential for understanding details of climate dynamics and climate change. Presently, such information is gathered individually from ground station networks and satellite platforms. Efforts are in progress to consolidate and analyze long-term station records from a number of countries. To gain truly global coverage, however, satellite-based monitoring techniques must be employed. A 27-year record of Northern Hemisphere continental snow cover produced by the National Oceanic and Atmospheric Administration (NOAA) is the longest such environmental record available. Records of Southern Hemisphere continental cover and snow on top of Arctic sea ice have been produced by similar means for a portion of this interval. The visible imagery charting technique used to generate these data provides information on snow extent but not on snow volume. Satellite microwave analyses over Northern Hemisphere lands show some promise in this regard, however, large-scale monitoring of snow extent with microwave data remains less accurate than visible charting. This paper updates the status of global snow cover monitoring, concentrating on the weekly snow charts prepared by NOAA and discussing a new and consistent record of monthly snow cover generated from these weekly charts. The NOAA charts show a reduction of hemispheric snow cover over the past five years, particularly in spring. Snow areas from the NOAA product are then compared with values derived using passive microwave data. The latter consistently reports less snow cover than the more accurate visible product. Finally, future snow monitoring initiatives are recommended. These include continuing the consistent NOAA product until an all-weather all-surface product is developed. The latter would use multiple data sources and geographic information systems techniques. Such an integrative product would need extensive comparisons with the NOAA product to ensure the continued utility of the lengthy NOAA observations in studies of climate change. In a retrospective sense, satellite charts from the middle 1960s to early 1970s need reevaluation and techniques to merge satellite products with historic station time series must be developed. Robinson, David A., Kenneth F. Dewey, Richard R. Heim, 1993: Global Snow Cover Monitoring: An Update. Bull. Amer. Meteor. Soc., 74, 1689–1696. doi: http://dx.doi.org/10.1175/1520-0477(1993)0742.0.CO;2. [Full text]

Interannual Variability of Wintertime Snow Cover across the Northern Hemisphere – Gutzler & Rosen (1992) “Digitized maps of Northern Hemisphere snow cover derived from visible satellite imagery are examined to assess the interannual variability of snow cover in winter months for years 1972–90. The secular trend of winter snow cover over the landmasses of Eurasia and North America during this period is extremely small in December and January. A decreasing trend of somewhat larger magnitude is observed in Eurasian snow cover in February. Fluctuations of detrended interannual snow-cover anomalies averaged over the Eurasian and North American continents are positively correlated. By subdividing the continents into longitudinal sectors it is determined that this intercontinental relationship is due to high correlations between European and North American sectors. The relationship of snow-cover fluctuations to large-scale circulation anomalies is described using lime series of teleconnection pattern indices derived from monthly mean geopotential height fields. A pattern of height anomalies resembling the North Atlantic Oscillation is correlated with snow-cover anomalies in North America and Europe. The Pacific-North American teleconnection pattern is highly correlated with snow-cover anomalies in western North America but has limited influence on intercontinental snow-cover fluctuations.” Gutzler, David S., Richard D. Rosen, 1992: Interannual Variability of Wintertime Snow Cover across the Northern Hemisphere. J. Climate, 5, 1441–1447. doi: http://dx.doi.org/10.1175/1520-0442(1992)0052.0.CO;2. [Full text]

Recent secular variations in the extent of Northern Hemisphere snow cover – Robinson & Dewey (1990) “Northern hemisphere snow cover during 1988 and 1989 was at its lowest extent since the advent of reliable satellite snow-cover monitoring in 1972; running some 8–10% below the eighteen-year annual mean of 25.7 million km2. Monthly minima for the period of record occurred six times during these two years. In general, the last nine years of the satellite record had less extensive cover than the 1972–80 interval. Negative anomalies during the 1980s were largest over Eurasia in all seasons, and in the Spring over North America. Hemispheric seasonal means for the most recent nine years were 3.7% to 8.4% lower than those between 1972 and 1980. Results are based on analyses of National Oceanic and Atmospheric Administration weekly snow charts, which are produced from visible satellite imagery.” David A. Robinson, Kenneth F. Dewey, Geophysical Research Letters, Volume 17, Issue 10, pages 1557–1560, September 1990, DOI: 10.1029/GL017i010p01557. [Full text]

A Digital Archive of Northern Hemisphere Snow Cover, November 1966 through December 1980 – Dewey & Heim (1982) “The purpose of this article is to acquaint the research community with a new data base—a digitized archive of Northern Hemisphere snow cover. Historically, those researchers who needed snow cover data for climatic and atmospheric boundary layer studies have had to rely on the irregularly spaced (and in some regions, sparse)grid of point observations. Northern Hemisphere Weekly Snow and Ice Cover Charts, which are created from analyzed satellite imagery at the National Earth Satellite Service (NESS), have been available on an operational basis since late 1966. Each of these weekly charts for the period November 1966 through December 1980 was digitized and stored in a new data archive. Snow cover area and snow cover frequency climatologies were created and examples are presented. The significance of this unique data archive is examined by comparing the 14-year mean annual snow cover frequency climatology with several published snow cover climatologies. The potential uses for this data archive in meteorological and climatological studies also are reviewed. Dewey, Kenneth F., Richard Heim, 1982: A Digital Archive of Northern Hemisphere Snow Cover, November 1966 through December 1980. Bull. Amer. Meteor. Soc., 63, 1132–1141. doi: http://dx.doi.org/10.1175/1520-0477(1982)0632.0.CO;2. [Full text]

Papers on 2003 heat wave in Europe

This is a list of papers on 2003 heat wave in Europe. The list is not complete, and will most likely be updated in future in order to make it more thorough and more representative.

Heat-related mortality in the Florentine area (Italy) before and after the exceptional 2003 heat wave in Europe: an improved public health response? – Morabito et al. (2012) “High ambient temperatures have been associated with increased mortality across the world. Several studies suggest that timely preventive measures may reduce heat-related excess mortality. The main aim of this study was to detect the temporal modification of heat-related mortality, in older adults (aged 65–74) and in elderly ≥75 years old, in the Florentine area by comparing previous (1999–2002) and subsequent (2004–2007) periods to the summer of 2003, when a regional Heat-Health Warning System (HHWS) was set up. Mortality data from 1999 to 2007 (May–September) were provided by the Mortality Registry of the Tuscany Region (n = 21,092). Weather data were used to assess daily apparent temperatures (AT). Case-crossover time-stratified designs and constrained segmented distributed lag models were applied. No significant heat-related mortality odds ratio (OR) variations were observed among the sub-periods. Nevertheless, a general OR decrease dating from 1999–2002 (OR 1.23; lack of HHWS) to 2004–2005 (OR 1.21; experimental HHWS running only for Florence) and to 2006–2007 (OR 1.12; official HHWS extended to the whole Florentine area) was observed when the maximum AT was considered. This modification was only evident in subjects ≥75 years old. The heat effect was higher and sustained for more days (until lag 9) during the period 1999–2002 than 2004–2007. The decrease of the excessive heat effect on mortality between periods with the absence and existence of a HHWS is also probably due to the mitigation of preventive measures and the implementation of a HHWS with specific interventions for safeguarding the health of the “frail elderly”.” Marco Morabito, Francesco Profili, Alfonso Crisci, Paolo Francesconi, Gian Franco Gensini, Simone Orlandini, International Journal of Biometeorology, September 2012, Volume 56, Issue 5, pp 801-810, DOI: 10.1007/s00484-011-0481-y.

Influence of sea surface temperature on the European heat wave of 2003 summer. Part I: an observational study – Feudale & Shukla (2011) “The heat wave affecting Europe during summer of 2003 is analyzed in detail with observational and reanalysis data. Surface, middle and upper troposphere analysis reveal particular circulation patterns related to an atmospheric blocking condition. In general seasonal anomalies, like this intense heat wave, are strongly related to boundary conditions. Composites and empirical orthogonal functions analysis provide evidence for an organized structure in the sea surface temperature (SST) anomaly field: high SSTs in the Mediterranean basin, the North Sea and further north toward the Arctic Circle were observed mainly in the months of June and August. The outcome of this analysis on observational data shows the SST as one of the possible factors in enhancing the heat wave in the European area.” Laura Feudale, Jagadish Shukla, Climate Dynamics, May 2011, Volume 36, Issue 9-10, pp 1691-1703, DOI: 10.1007/s00382-010-0788-0. [Full text]

Influence of sea surface temperature on the European heat wave of 2003 summer. Part II: a modeling study – Feudale & Shukla (2011) “The Center for Ocean–Land–Atmosphere Studies Atmospheric General Circulation Model is used to investigate the role of global boundary conditions of sea surface temperature (SST) in the establishment and maintenance of the European heat wave of 2003 summer. It is found that the global SST anomalies can explain many major features of the European heat wave during the summer of 2003. A further experiment has investigated the role of SST outside the Mediterranean area. This supplements the results of a previous study where the role of warm Mediterranean SST was analyzed. The results suggest that the SST anomalies had an additional effect of reducing the baroclinicity in the European area reinforcing the blocking circulation and helping to create ideal conditions for the establishment of the heat wave.” Laura Feudale, Jagadish Shukla, Climate Dynamics, May 2011, Volume 36, Issue 9-10, pp 1705-1715, DOI: 10.1007/s00382-010-0789-z.

Impact of aerosol direct radiative forcing on the radiative budget, surface heat fluxes, and atmospheric dynamics during the heat wave of summer 2003 over western Europe: A modeling study – Péré et al. (2011) “In this work, an off-line coupling between the chemistry-transport model CHIMERE (associated with an aerosol optical module) and the meteorological model Weather Research and Forecasting (WRF) is used to study (1) the direct radiative forcing of pollution aerosols during the heat wave of summer 2003 over western Europe and (2) the possible feedbacks of this direct radiative forcing on the surface-atmosphere system. Simulations performed for the period 7–15 August 2003 reveal a significant decrease of daily mean solar radiation reaching the surface (ΔF_BOA = −(10–30) W/m²) because of back scattering at the top of the atmosphere (ΔF_TOA = −(1–12) W/m²) and also absorption of solar radiation by polluted particles (ΔF_atm = + (5–23) W/m²). During daytime, the aerosol surface dimming induces a mean reduction of both sensible (16 W/m²) and latent (21 W/m²) heat fluxes emitted by the terrestrial surface, resulting in a radiative cooling of the air near the surface (up to 2.9 K/d at noon). Simultaneously, the absorption of solar energy by aerosols causes an atmospheric radiative heating within the planetary boundary layer reaching 1.20 K/d at noon. As a consequence, the direct radiative effect of aerosols is shown to reduce both the planetary boundary layer height (up to 30%) and the horizontal wind speed (up to 6%); that may have contributed to favor the particulate pollution during the heat wave of summer 2003.” J. C. Péré, M. Mallet, V. Pont, B. Bessagnet, Journal of Geophysical Research: Atmospheres (1984–2012), Volume 116, Issue D23, December 2011, DOI: 10.1029/2011JD016240.

A Review of the European Summer Heat Wave of 2003 – García-Herrera et al. (2010) “This paper reviews the European summer heat wave of 2003, with special emphasis on the first half of August 2003, jointly with its significant societal and environmental impact across Western and Central Europe. We show the pattern of record-breaking temperature anomalies, discuss it in the context of the past, and address the role of the main contributing factors responsible for the occurrence and persistence of this event: blocking episodes, soil moisture deficit, and sea surface temperatures. We show that the anticyclonic pattern corresponds more to an anomalous northern displacement of the North Atlantic subtropical high than a canonical blocking structure, and that soil moisture deficit was a key factor to reach unprecedented temperature anomalies. There are indications that the anomalous Mediterranean Sea surface temperatures (SSTs) have contributed to the heat wave of 2003, whereas the role of SST anomalies in other oceanic regions is still under debate. There are methodological limitations to evaluate excess mortality due to excessive temperatures; however, the different studies available in the literature allow us to estimate that around 40,000 deaths were registered in Europe during the heat wave, mostly elderly persons. Despite previous efforts undertaken by a few cities to implement warning systems, this dramatic episode has highlighted the widespread un-preparedness of most civil and health authorities to cope with such large events. Therefore, the implementation of early warning systems in most European cities to mitigate the impact of extreme heat is the main consequence to diminish the impact of future similar events. In addition to mortality (by far the most dramatic impact), we have also analyzed the record-breaking forest fires in Portugal and the evidence of other relevant impacts, including agriculture and air pollution.” R. García-Herrera, J. Díaz, R. M. Trigo, J. Luterbacher & E. M. Fischer, Critical Reviews in Environmental Science and Technology, Volume 40, Issue 4, 2010, DOI:10.1080/10643380802238137.

Increase in out-of-hospital cardiac arrest attended by the medical mobile intensive care units, but not myocardial infarction, during the 2003 heat wave in Paris, France – Empana et al. (2009) “Objectives: To address the association between the 2003 heat wave in Paris (France) and the occurrence of out-of-hospital cardiac arrest. Design: An analysis of the interventions of the medical mobile intensive care units of the City of Paris for out-of-hospital cardiac arrest and prehospital myocardial infarctions, which were routinely and prospectively computerized from January 1, 2000, to December 31, 2005. Setting: City of Paris, France. Patients: Participants were consecutive victims of witnessed out-of-hospital cardiac arrest due to heart disease and of ST-segment elevation myocardial infarction (STEMI) aged ≥18 yrs, who were attended by the medical mobile intensive care units (MICUs) of the City of Paris from January 1, 2000, to December 31, 2005. Interventions: None. Measurements and Main Results: The numbers of out-of-hospital cardiac arrests and of STEMIs during the 2003 heat wave period (August 1 to August 14) were compared (Poisson regression analysis) with the respective average numbers during the same period in reference years 2000–2002 and 2004–2005 when there was no heat wave. Mean ages of the 3049 patients experiencing out-of-hospital cardiac arrest and the 2767 patients experiencing STEMI attended by the MICUs during the study period were 64.3 ± 18.0 and 65.2 ± 15.4, respectively, and two thirds were males. During the heat wave period, the number of out-of-hospital cardiac arrests (n = 40) increased 2.5-fold compared with the reference periods (n = 81 for 5 yrs; p < .001); this corresponded to an estimated relative rates of out-of-hospital cardiac arrests of 2.34 (95% confidence interval, 1.60–3.41), after adjustment for age and for gender. This increase was observed in both genders (p for interaction with gender = .48) but only in those who were aged ≥60 yrs (p for interaction with age = .005). No variation was found for myocardial infarctions during heat wave. Conclusions: These data suggest that a heat wave may be associated with an increased risk of sudden cardiac death in the population.” Empana, Jean-Philippe MD, PhD; Sauval, Patrick MD; Ducimetiere, Pierre PhD†; Tafflet, Muriel MPH; Carli, Pierre MD; Jouven, Xavier MD, PhD, Critical Care Medicine: December 2009 – Volume 37 – Issue 12 – pp 3079-3084, doi: 10.1097/CCM.0b013e3181b0868f.

Air pollution during the 2003 European heat wave as seen by MOZAIC airliners – Tressol et al. (2008) “This study presents an analysis of both MOZAIC profiles above Frankfurt and Lagrangian dispersion model simulations for the 2003 European heat wave. The comparison of MOZAIC measurements in summer 2003 with the 11-year MOZAIC climatology reflects strong temperature anomalies (exceeding 4°C) throughout the lower troposphere. Higher positive anomalies of temperature and negative anomalies of both wind speed and relative humidity are found for the period defined here as the heat wave (2–14 August 2003), compared to the periods before (16–31 July 2003) and after (16–31 August 2003) the heat wave. In addition, Lagrangian model simulations in backward mode indicate the suppressed long-range transport in the mid- to lower troposphere and the enhanced southern origin of air masses for all tropospheric levels during the heat wave. Ozone and carbon monoxide also present strong anomalies (both ~+40 ppbv) during the heat wave, with a maximum vertical extension reaching 6 km altitude around 11 August 2003. Pollution in the planetary boundary layer (PBL) is enhanced during the day, with ozone mixing ratios two times higher than climatological values. This is due to a combination of factors, such as high temperature and radiation, stagnation of air masses and weak dry deposition, which favour the accumulation of ozone precursors and the build-up of ozone. A negligible role of a stratospheric-origin ozone tracer has been found for the lower troposphere in this study. From 29 July to 15 August 2003 forest fires burnt around 0.3×10⁶ ha in Portugal and added to atmospheric pollution in Europe. Layers with enhanced CO and NO_y mixing ratios, advected from Portugal, were crossed by the MOZAIC aircraft in the free troposphere over Frankfurt. A series of forward and backward Lagrangian model simulations have been performed to investigate the origin of anomalies during the whole heat wave. European anthropogenic emissions present the strongest contribution to the measured CO levels in the lower troposphere (near 30%). This source is followed by Portuguese forest fires which affect the lower troposphere after 6 August 2003 and even the PBL around 10 August 2003. The averaged biomass burning contribution reaches 35% during the affected period. Anthropogenic CO of North American origin only marginally influences CO levels over Europe during that period.” Tressol, M., Ordonez, C., Zbinden, R., Brioude, J., Thouret, V., Mari, C., Nedelec, P., Cammas, J.-P., Smit, H., Patz, H.-W., and Volz-Thomas, A.: Air pollution during the 2003 European heat wave as seen by MOZAIC airliners, Atmos. Chem. Phys., 8, 2133-2150, doi:10.5194/acp-8-2133-2008, 2008. [Full text]

General and specific mortality among the elderly during the 2003 heat wave in Genoa (Italy) – Conti et al. (2007) “The effects of heat waves on health can be serious for elderly persons, especially those in urban areas. We investigated in-depth the mortality excess during the 2003 heat wave among elderly persons (>74 years) in the City of Genoa (Italy). The excess in general mortality was calculated for the period July 16–August 31, as the ratio of observed to expected deaths. To evaluate “harvesting”, we compared observed and expected mortality in the period September 2003–April 2004. We also studied the relationship between mortality and climatic conditions considering daily maximum temperature and Humidex discomfort degrees, as well as “lag-time”. For cause-specific mortality, we considered all pathologies reported on the death certificate. The excess in general mortality was significant and was greatest in the first half of August. During Summer 2003, in Genoa the climatic conditions (described in terms of maximum temperature and Humidex Index) were extremely hot; regarding lag-time, the greatest correlation between the number of observed deaths and the maximum temperature values was observed for the three preceding days (ρ=0.568; significance level <0.01). The prominent causes of death, for which an excess was observed, were cerebrovascular diseases, severe respiratory diseases, severe renal diseases, dementia; moreover, certain pathologic conditions and symptoms, usually not lethal, were also frequent causes of death (e.g., hypovolemia, hyperpyrexia, decubitus ulcers and immobilization syndrome). The results of this study confirm the relationship between the heat waves and death among elderly, stressing that, because of their poorer physical health and the prevalence of cognitive disturbances that hinder risk perception, it is necessary to properly care for them during heat waves.” Susanna Conti, Maria Masocco, Paola Meli, Giada Minelli, Ernesto Palummeri, Renata Solimini, Virgilia Toccaceli, Monica Vichi, Environmental Research, Volume 103, Issue 2, February 2007, Pages 267–274, http://dx.doi.org/10.1016/j.envres.2006.06.003.

Excess mortality related to the August 2003 heat wave in France – Fouillet et al. (2006) “Objectives: From August 1st to 20th, 2003, the mean maximum temperature in France exceeded the seasonal norm by 11–12°C on nine consecutive days. A major increase in mortality was then observed, which main epidemiological features are described herein. Methods: The number of deaths observed from August to November 2003 in France was compared to those expected on the basis of the mortality rates observed from 2000 to 2002 and the 2003 population estimates. Results: From August 1st to 20th, 2003, 15,000 excess deaths were observed. From 35 years age, the excess mortality was marked and increased with age. It was 15% higher in women than in men of comparable age as of age 45 years. Excess mortality at home and in retirement institutions was greater than that in hospitals. The mortality of widowed, single and divorced subjects was greater than that of married people. Deaths directly related to heat, heatstroke, hyperthermia and dehydration increased massively. Cardiovascular diseases, ill-defined morbid disorders, respiratory diseases and nervous system diseases also markedly contributed to the excess mortality. The geographic variations in mortality showed a clear age-dependent relationship with the number of very hot days. No harvesting effect was observed. Conclusions: Heat waves must be considered as a threat to European populations living in climates that are currently temperate. While the elderly and people living alone are particularly vulnerable to heat waves, no segment of the population may be considered protected from the risks associated with heat waves.” A. Fouillet, G. Rey, F. Laurent, G. Pavillon, S. Bellec, C. Guihenneuc-Jouyaux, J. Clavel, E. Jougla and Denis Hémon, International Archives of Occupational and Environmental Health, Volume 80, Number 1, 16-24, DOI: 10.1007/s00420-006-0089-4. [Full text]

The 2003 Heat Wave in France: Dangerous Climate Change Here and Now – Poumadère et al. (2005) “In an analysis of the French episode of heat wave in 2003, this article highlights how heat wave dangers result from the intricate association of natural and social factors. Unusually high temperatures, as well as socioeconomic vulnerability, along with social attenuation of hazards, in a general context where the anthropogenic contribution to climate change is becoming more plausible, led to an excess of 14,947 deaths in France, between August 4 and 18, 2003. The greatest increase in mortality was due to causes directly attributable to heat: dehydration, hyperthermia, heat stroke. In addition to age and gender, combinatorial factors included preexisting disease, medication, urban residence, isolation, poverty, and, probably, air pollution. Although diversely impacted or reported, many parts of Europe suffered human and other losses, such as farming and forestry through drought and fires. Summer 2003 was the hottest in Europe since 1500, very likely due in part to anthropogenic climate change. The French experience confirms research establishing that heat waves are a major mortal risk, number one among so-called natural hazards in postindustrial societies. Yet France had no policy in place, as if dangerous climate were restricted to a distant or uncertain future of climate change, or to preindustrial countries. We analyze the heat wave’s profile as a strongly attenuated risk in the French context, as well as the causes and the effects of its sudden shift into amplification. Research and preparedness needs are highlighted.” Marc Poumadère, Claire Mays, Sophie Le Mer, Russell Blong, Risk Analysis
Volume 25, Issue 6, pages 1483–1494, December 2005, DOI: 10.1111/j.1539-6924.2005.00694.x. [Full text]

The impact of the summer 2003 heat waves on mortality in four Italian cities – Michelozzi et al. (2005) “This study evaluates the impact of the 2003 heat wave on cause-specific mortality and the role of demographic characteristics and socioeconomic conditions that may have increased the risk of mortality in four Italian cities: Bologna, Milan, Rome and Turin. Daily mortality counts, for the resident population by age, sex and cause of death were considered. Daily excess mortality was calculated as the difference between the number of deaths observed and the smoothed average. The impact of heat on health is measured in terms of maximum apparent temperature. The greatest excess in mortality was observed in the north west of Italy (Turin, +23% and Milan, +23%). The old (75-84 years) and the very old (85+ years) were the age groups most affected, and when stratifying by sex, the increase in mortality seemed to be greater among females. The greatest excess in mortality was registered in those with low socioeconomic status in Rome (+17.8%) and in those with lower education levels in Turin (+43%). The analysis of cause-specific mortality not only confirms results from previous studies of an increase in heat-related mortality by respiratory and cardiovascular diseases, but also shows a significant excess in mortality for diseases of the central nervous system and for metabolic/endocrine disorders. Results from 2003 highlight the necessity of targeting future prevention programmes at the susceptible sub-groups identified. The introduction of warning systems alongside efficient preventive plans and the monitoring of mortality during heat waves may represent a valid tool for the reduction of heat-related deaths.” Michelozzi P, de Donato F, Bisanti L, Russo A, Cadum E, DeMaria M, D’Ovidio M, Costa G, Perucci CA, Euro Surveillance : Bulletin Europeen sur les Maladies Transmissibles = European Communicable Disease, Bulletin [2005, 10(7):161-5].

Summary of the mortality impact assessment of the 2003 heat wave in France – Pirard et al. (2005) “France experienced a record-breaking heat wave between 2 and 15 August 2003. All the French regions were affected by this heat wave, which resulted in an excess of 14 800 deaths between 1 and 20 August. The increase in the number of excess deaths followed the same pattern as the increase in temperatures. No deviance from the normal death rate was observed in the month of August during the last third of the month, nor during the following three months. There was a clear discrepancy in the impact of the heat wave from city to city. If the effect of duration of consecutive days with high minimal temperatures and deviance with the seasonal normal temperature was patent, this could not explain all of the observed variability of the death incidence. The victims were mainly elderly women older than 75 years. In terms of relative risk and contribution to the global toll, deaths linked to heat were the most important. Based on these results, the French government developed a Heat Health Watch Warning System and set up a preventive action plan for each region in 2004.” Pirard P, Vandentorren S, Pascal M, Laaidi K, Le Tertre A, Cassadou S, Ledrans M, Euro Surveillance : Bulletin Europeen sur les Maladies Transmissibles = European Communicable Disease Bulletin [2005, 10(7):153-6].

Epidemiologic study of mortality during the Summer 2003 heat wave in Italy – Conti et al. (2005) “Introduction: It is widely recognized that extreme climatic conditions during summer months may constitute a major public health threat. Owing to what is called the “urban heat island effect,” as well as to the consequences of heat waves on health, individuals living in cities have an elevated risk of death when temperature and humidity are high compared to those living in suburban and rural areas. Studies on heat wave-related mortality have further demonstrated that the greatest increases in mortality occur in the elderly. Following the unusually hot summer of 2003 and the dramatic news from neighboring countries such as France, the Italian Minister of Health requested the Istituto Superiore di Sanità-Bureau of Statistics to undertake an epidemiologic study of mortality in Italy during Summer 2003 to investigate whether there had been an excess of deaths, with a particular focus on the elderly population. Materials and methods: Communal offices, which maintain vital statistics, were asked for the individual records of death of residents registered daily during the period 1 June–31 August 2003 and during the same period of 2002 for each of the 21 capitals of the Italian regions. As it was necessary to obtain mortality data quickly from many municipalities and to make the analysis as soon as possible, the method adopted was comparison of mortality counts during the heat wave with figures observed during the same period of the previous year. Results: Compared with 2002, between 1 June and 31 August 2003, there was an overall increase in mortality of 3134 (from 20,564 to 23,698). The greatest increase was among the elderly; 2876 deaths (92%) occurred among people aged 75 years and older, a more than one-fifth increase (21.3%, from 13.517 to 16.393%). The highest increases were observed in the northwestern cities, which are generally characterized by cold weather, and in individuals 75 years and older: Turin (44.9%), Trento (35.2%), Milan (30.6%), and Genoa (22.2%). Of note are also the increases observed in two southern cities, L’Aquila (24.7%) and Potenza (25.4%), which are located, respectively, at 700 and 800 m above see level. For Bari and Campobasso, both in the South, with a typically hot summer climate, the increase during the last 15 days of August was 186.2 and 450%, respectively. Conclusions: The relationship between mortality and discomfort due to climatic conditions as well as the short lag time give a clear public health message: preventive, social, and health care actions must be administered to the elderly and the frail to avoid excess deaths during heat waves.” Susanna Conti, Paola Meli, Giada Minelli, Renata Solimini, Virgilia Toccaceli, Monica Vichi, Carmen Beltrano, Luigi Perini, Environmental Research, Volume 98, Issue 3, July 2005, Pages 390–399, http://dx.doi.org/10.1016/j.envres.2004.10.009.

The 2003 heat wave as an example of summers in a greenhouse climate? Observations and climate model simulations for Basel, Switzerland – Beniston & Diaz (2004) “The heat wave that affected many parts of Europe during the course of summer 2003 may be a harbinger of summers that could occur more regularly in a future climate, under enhanced greenhouse gas concentrations. Switzerland was not exempt from the 2003 heat wave and, indeed, the previous absolute maximum temperature record dating back to the middle of the 20th century was exceeded by over 2 °C. Regional climate simulations undertaken for the European region emphasize the fact that summers will become progressively as hot as the 2003 event, such that, in the latter part of the 21st century, it is likely to become the norm. On the basis of this study, the 2003 event should be considered as a “shape of things to come” and thereby prompt timely decision making in terms of appropriate adaptation and mitigation strategies.” Martin Beniston, Henry F. Diaz, Global and Planetary Change, Volume 44, Issues 1–4, December 2004, Pages 73–81, http://dx.doi.org/10.1016/j.gloplacha.2004.06.006. [Full text]

The 2003 heat wave in Europe: A shape of things to come? An analysis based on Swiss climatological data and model simulations – Beniston (2004) “The 2003 heat wave that affected much of Europe from June to September bears a close resemblance to what many regional climate models are projecting for summers in the latter part of the 21st century. Model results suggest that under enhanced atmospheric greenhouse-gas concentrations, summer temperatures are likely to increase by over 4°C on average, with a corresponding increase in the frequency of severe heat waves. Statistical features of the 2003 heat wave for the Swiss site of Basel are investigated and compared to both past, 20th century events and possible future extreme temperatures based on model simulations of climatic change. For many purposes, the 2003 event can be used as an analog of future summers in coming decades in climate impacts and policy studies.” Beniston, M. (2004), The 2003 heat wave in Europe: A shape of things to come? An analysis based on Swiss climatological data and model simulations, Geophys. Res. Lett., 31, L02202, doi:10.1029/2003GL018857. [Full text]

Mortality in 13 French Cities During the August 2003 Heat Wave – Vandentorren et al. (2004) “We observed the daily trend in mortality rates during the 2003 heat wave in 13 of France’s largest cities. Mortality data were collected from July 25 to September 15 each year from 1999 through 2003. The conjunction of a maximum temperature of 35°C and a minimum temperature of 20°C was exceptional in 7 cities. An excess mortality rate was observed in the 13 towns, with disparities from +4% (Lille) to +142% (Paris).” Stéphanie Vandentorren, Florence Suzan, Sylvia Medina, Mathilde Pascal, Adeline Maulpoix, Jean-Claude Cohen, and Martine Ledrans Mortality in 13 French Cities During the August 2003 Heat Wave. American Journal of Public Health: September 2004, Vol. 94, No. 9, pp. 1518-1520, doi: 10.2105/AJPH.94.9.1518. [Full text]

Air pollution related deaths during the 2003 heat wave in the Netherlands – Fischer et al. (2004) “In the Netherlands an excess of 1000–1400 deaths was estimated due to the hot temperatures that occurred during the 2003 summer period. We estimated the number of deaths attributable to the ozone and Particular Matter (PM₁₀) concentrations in the summer period June–August 2003. Our calculations show that an excess of around 400–600 air pollution-related deaths may have occurred compared to an ‘average’ summer. These calculations suggest that in the Netherlands, a significant proportion of the deaths now being attributed to the hot summer weather can reasonably be expected to have been caused by air pollution.” Paul H. Fischer, Bert Brunekreef, Erik Lebret, Atmospheric Environment, Volume 38, Issue 8, March 2004, Pages 1083–1085, http://dx.doi.org/10.1016/j.atmosenv.2003.11.010.

The role of increasing temperature variability in European summer heatwaves – Schär et al. (2004) “Instrumental observations and reconstructions of global and hemispheric temperature evolution reveal a pronounced warming during the past 150 years. One expression of this warming is the observed increase in the occurrence of heatwaves. Conceptually this increase is understood as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small. Here we show that this framework fails to explain the record-breaking central European summer temperatures in 2003, although it is consistent with observations from previous years. We find that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account. We propose that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003. To test this proposal, we simulate possible future European climate with a regional climate model in a scenario with increased atmospheric greenhouse-gas concentrations, and find that temperature variability increases by up to 100%, with maximum changes in central and eastern Europe.” Christoph Schär, Pier Luigi Vidale, Daniel Lüthi, Christoph Frei, Christian Häberli, Mark A. Liniger & Christof Appenzeller, Nature 427, 332-336 (22 January 2004) | doi:10.1038/nature02300. [Full text]

Simplistic explanations of climate related issues

There’s a page that lists texts written by people trying to describe complex scientific issues by using only the thousand most used words in English language. To go with this, there’s an online editor that warns you if you have used a word outside of the thousand most used words. The Way Things Break had a good go at this.

There, and I also seen it mentioned in private communication, it was said that this is a bad communications tool. It is that. The things explained with only 1000 words are sometimes hard to read and understand because descriptions have to take quite strange routes to explain things. But I don’t think the point of this excercise is to provide a good communications tool. I think it’s a good way to get you thinking how to describe things in a more simple manner, but most importantly, I think it’s just fun word game.

So, I did a couple of short ones with the editor. Here’s the first:

Some type of light can be seen and some type of light can not be seen. In this rock ball where we live, air does not let all types of light go through. Light that can be seen goes through the air well but some of the light that can not be seen does not go through the air that well.

Light that can be seen from the sun goes through the air and hits the ground, which warms and sends warm type of light, which can not be seen, to the air. Air does not let all the warm type light through. Air stops some of it and sends it again to all directions, so some of it also goes back to ground. That makes ground warm even more.

And the second one:

This word I can not write here tells the mean situation of the air around you. It tells how warm it has been as 30 year mean, so short time changes are not what this word is about. It also tells how much rain there has been during long time. White soft looking things in the sky can change how warm or how much rain there is in the air around you. Another important thing for that is the sun. Also how the air and water go around in the world can change the situation with the air around you. There are also some other things that can cause changes to the air situation, such as small matter pieces in the air, different types of air that stop some types of light, and high rock things that send fire and hot rocks to the sky with loud sound.

Yesterday’s papers

Over two years ago I published a post containing all papers that had arrived to my RSS feed reader in one morning. I decided to have another go at this but this time for a full day. So, here I give a list of all papers that arrived to my RSS feed reader during a single day. I started this at noon January 23rd and continued until noon January 24th of 2013 (given times are in Finnish time). No editorials, corrections, comment papers, or reply papers were included, but just the new research papers. I also excluded papers that clearly were not climate related (there were about 10 or so such papers). The list below still contains some papers which are only very vaguely related to climate.

It should be noted here that these are only the papers that arrived to my RSS feed reader. I don’t have all journals in there that are publishing climate change related papers. In my feed reader I only have few ecology journals but basically all biology journals can publish climate change related papers (at least on how climate change affects species or ecosystems). I don’t have any journals that are devoted to climate or energy policy, and I only have couple of journals on mitigation/adaptation issues. I don’t have general science journals (Nature, Science, PNAS,…). Additionally almost any journal of any trade can publish an occasional climate change paper. This is just to say that below is not all climate related science that got published yesterday.

The list

1. Intensity of Climate Variability Derived from the Satellite and MERRA Reanalysis Temperatures: AO, ENSO, and QBO – Yoo et al.

2. Near Surface atmospheric response to the Total Solar Eclipse at Dibrugarh on 22 July, 2009 – Rao et al.

3. Channel electron multiplier operated on a sounding rocket without a cryogenic vacuum pump from 120 –80 km altitude – Dickson et al.

4. Response of methane emissions from wetlands to the Last Glacial Maximum and an idealized Dansgaard–Oeschger climate event: insights from two models of different complexity – Ringeval et al.

5. Tree-ring-based reconstructions of North American glacier mass balance through the Little Ice Age — Contemporary warming transition – Malcomb & Wiles.

6. Vegetation history in central Kentucky and Tennessee (USA) during the last glacial and deglacial periods – Liu et al.

7. A model-based constraint on CO2 fertilisation – Holden et al.

8. A method to automatically determine sea level for referencing snow freeboards and computing sea ice thicknesses from NASA IceBridge airborne LIDAR – Wang et al.

9. Recovering missing pixels for Landsat ETM + SLC-off imagery using multi-temporal regression analysis and a regularization method – Zeng et al.

10. MODIS-based corn grain yield estimation model incorporating crop phenology information – Sakamoto et al.

11. Updated analyses of temperature and precipitation extreme indices since the beginning of the twentieth century: The HadEX2 dataset – Donat et al.

12. Modeling aerosols and their interactions with shallow cumuli during the 2007 CHAPS field study – Shrivastava et al.

13. Effects of atmospheric light scattering on spectroscopic observations of greenhouse gases from space. Part 2: Algorithm intercomparison in the GOSAT data processing for CO2 retrievals over TCCON sites – Oshchepkov et al.

14. Assessment of surface winds over the Atlantic, Indian and Pacific Ocean sectors of the Southern Ocean in CMIP5 models: historical bias, forcing response, and state dependence – Bracegirdle et al.

15. Global Seasonal Variations of Midday Planetary Boundary Layer Depth from CALIPSO Space-Borne LIDAR – McGrath-Spangler & Denning.

16. Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) to a coastal site of Hong Kong, South China – Liu et al.

17. Current status and future trends of SO2 and NOx pollution during the 12th FYP period in Guiyang city of China – Tian et al.

18. Chemostratigraphy of the early Pliocene diatomite interval from MIS AND-1B core (Antarctica): Paleoenvironment implications – Scopelliti et al.

19. Blowin’ in the wind: Short-term weather and belief in anthropogenic climate change – Hamilton & Stampone.

20. The Lisbon Earthquake of 1755 and Superstorm Sandy: The Need to Understand Long-Term Impacts – Balstad.

21. Dissolved inorganic carbon and alkalinity fluxes from coastal marine sediments: model estimates for different shelf environments and sensitivity to global change – Krumins et al.

22. Prediction, time variance, and classification of hydraulic response to recharge in two karst aquifers – Long & Mahler.

23. Does Antarctic glaciation cool the world? – Goldner et al.

24. A lacustrine sedimentary record of Holocene periglacial activity from the Uinta Mountains, Utah, U.S.A. – Munroe et al.

25. Assessment of potential suspended sediment yield in Japan in the 21st century with reference to the general circulation model climate change scenarios – Mouri et al.

26. Changes in precipitation extremes on the Black Sea Western Coast – Croitoru et al.

Non-English climate science

Today we are used to receiving new climate research written in English. That has not always been the case. There even was a time when English was a very minor language in science. Some time ago I started thinking that by concentrating on research written in English we might be missing lot of climate science, especially historically. I decided to take a look at the situation.

I used Google Scholar and Google Translator for searching papers containing the word “climate” in all languages supported by Google Translator. I recorded the number of hits for each language. Results of this are shown below in a table. Note that this analysis is very rough, so I suggest that the presented numbers should only be taken as directional, and that the big picture presented in the table is more meaningful. The resulting numbers have a lot of uncertainties, some of which I explain below. Here’s the result table:

Country/language	Word	Results
English/Latin	climate	2550000
Spanish/Italian/Portuguese	clima	954000
China-simple	气候	614000
Germany/Norway/Denmark	klima	350000
France/Romania	climat	318000
Russia/Serbia	климат	93800
Japan	気候	49400
Turkey	iklim	43600
Sweden/Poland	klimat	34100
Korea	기후	33900
China-traditional	氣候	31100
Netherlands/Afrikaans	klimaat	24100
Ukraine/Belarus	клімат	23500
Albania	klimë	7600
Arabic	مناخ	6610
Lithuania	klimatas	6270
Finland	ilmasto	3980
Persia	اقلیم	3850
Greece	κλίμα	3500
Esperanto	klimato	3480
Czech	podnebí	2830
Vietnam	khí hậu	1390
Azerbaijan	iqlim	883
Hindi	जलवायु	821
Estonia	kliima	584
Slovenia	podnebne	575
Slovakia	podnebie	346
Thailand	ภูมิอากาศ	468
Latvia	klimats	255
Hebrew	האקלים	244
Iceland	loftslag	179
Swahili	hali ya hewa	113
Yiddish	קלימאַט	83
Welsh	yn yr hinsawdd	28
Armenia	կլիմա	18
Irish	aeráide	12
Urdu	آب و ہوا	3
Gujarati	આબોહવા	1

There are 2,550,000 hits in the English/Latin. Non-English (excluding Latin of course) languages have 2,235,364 hits. So, it seems that almost an equal number of climate papers exist in English as in non-English languages. Some languages are missing from the table because they didn’t produce any hits (and of course lot of others that are not supported by Google Scholar).

Like I mentioned above, the numbers have a lot of uncertainties. Google Scholar returns a lot more search results than just peer-reviewed papers. There are books, reports, and even some blog posts. This distorts the resulting number of hits. This seems to be a substantial problem for example in the search results for my native language, Finnish.

Another source of error is that Google Scholar returns search results for both author names and journal names. This is a big issue for example in German results. There seems to be lot of papers published by many authors who have the last name “Klima”. 350,000 hits for the German language therefore seems to be off by quite a lot. A search for “Klimawandel” (climate change) resulted in 21,900 hits. English “climate change” gives 1,570,000 hits, so the resulting ratio of climate/climate change = 1.62 for English. Assuming the same ratio for German, it would result in 21,900 * 1.62 = 35,600 hits for “klima” (climate). However, this feels somewhat too low considering that German is a common language in science, and that other comparable languages have many more hits (for example, French has over 318,000 hits – but see below for the need to correct French results). Also, most of Hungary’s results seem to be from author’s names.

Yet another problem is that not all of the search results are in the language that was intended. This is partly due to the issue mentioned above about Google Scholar returning results both for author and journal names. There are also occasions where another language has the same word (or close enough for Google Scholar) in another meaning, or has an author’s name matching the search word. French search results, for example, includepapers in other languages. According to the first result page (yes, I know it’s not a very big sample…), French results are 20% non-French. This would reduce the number of French language hits to 254,400.

Albania’s word for climate is “klimë”, but almost all search results are for “klime”, so Google Scholar sometimes gives additional results for words that are close to the actual search.

Search results might also not be climate related. The word “climate” has other, non-meteorological, meanings. Such as the political climate, or a climate of fear. The possibility for this source of error might be even worse for some other languages.

There are also duplicate entries for some papers. And these probably are not all error sources. Some non-English papers have also been published in English (or vice versa), so the ratio of non-English and English papers (= 0.87) might not be accurate. Additionally, some non-English papers have English abstracts.

So, it seems that despite all of my search results, there are not 5 million climate papers out there. But there are a lot of them – and quite a few of them might be in a language other than the English and Finnish that I understand. It sure would be nice to be able to read all those papers when needed.

Papers on the Anthropocene

This is a list of papers on the new geological epoch called the Anthropocene. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

The Anthropocene: is there a geomorphological case? – Brown et al. (2013) “The ‘Anthropocene’, as used to describe the interval of recent Earth history during which humans have had an ‘overwhelming’ effect on the Earth system, is now being formally considered as a possible new geological Epoch. Such a new geological time interval (possibly equivalent to the Pleistocene Epoch) requires both theoretical justification as well as empirical evidence preserved within the geological record. Since the geological record is driven by geomorphological processes, geomorphology has to be an integral part of this consideration given that it is Earth surface processes that produce terrestrial and near-shore stratigraphy. For this reason, the British Society for Geomorphology (BSG) has inaugurated a Fixed Term Working Group to consider this issue and advise the Society on how geomorphologists can engage with debates over the Anthropocene. This Commentary sets out the initial case for the formalisation of the Anthropocene and a priori considerations in the hope that it will stimulate debate amongst, and involvement by, the geomorphological community in what is a crucial issue for the discipline. The working Group is now considering the practical and aspects of such a formalisation including the relative magnitude problem, the boundary problem and the spatial diachrony of ‘anthropogenic geomorphology’.” Antony G. Brown, Stephen Tooth, Richard C. Chiverrell, Jim Rose, David S. G. Thomas, John Wainwright, Joanna E. Bullard, Varyl Thorndycraft, Rolf Aalto, Peter Downs, Earth Surface Processes and Landforms, DOI: 10.1002/esp.3368.

Agro-industrial alluvium in the Swale catchment, northern England, as an event marker for the Anthropocene – Foulds et al. (2013) “Physically and chemically distinctive late-Prehistoric and historical age alluvial deposits are characteristic of many upland and lowland river systems in the UK. Despite their widespread distribution, there have been few attempts to construct robust chronologies or to identify environmental factors that governed their formation. The Swale catchment in northern England is typical in this respect, with large areas of its valley floor covered by sedimentologically distinctive laminated sands and silts, enriched in organic material and Pb, and underlain by uncontaminated and structureless silts. Using ¹⁴C dating, chemostratigraphy, lichenometry and historical maps, a catchment-wide change in sedimentation style has been dated to between the mid 18th and early 19th centuries AD. Several causative factors were responsible for this change in sedimentation style and include the initiation of large-scale, intensive lead mining from the latter half of the 18th century onwards, embankment construction in the lowlands and historical peat erosion in the uplands. Transformation of the Swale floodplain also reflects longer-term land-use and climate change. In particular, deforestation of headwater tributaries by monastic grazing practices in the High Middle Ages (AD 1000–1300) led to a period of fine-grained sedimentation in upland catchments, as well as priming hillslopes for erosion and widespread channel network incision and increased fine sediment flux during the climatic downturn of the ‘Little Ice Age’. Sediment facies of a similar nature have been widely recorded in other northern English river catchments and represent a regional land use–climate signal characteristic of the Anthropocene. We introduce the term ‘agro-industrial alluvium’ to describe these types of deposit. They have similarities to post-settlement alluvium in North America and Australia, where historical land-use change had a similar impact on valley floor sedimentology.” Simon A Foulds, Mark G Macklin, Paul A Brewer, The Holocene January 8, 2013 0959683612465445, doi: 10.1177/0959683612465445.

Holocene and Anthropocene Landscape Change: Arroyo Formation on Santa Cruz Island, California – Perroy et al. (2012) “In this study, we untangle the relative importance of climatic, tectonic, and anthropogenic drivers as triggers of arroyo formation and geomorphic change for a small watershed on Santa Cruz Island, California. Within the Pozo watershed (6.47 km²), historic arroyo incision occurred contemporaneously with arroyo incision across many of the world’s dryland regions. Unlike many of these other sites, Pozo contains a datable record that allows quantification of sedimentation rates from the mid-to-late Holocene to the twentieth century. Basin-wide environmental changes were assessed using a combination of cosmogenic radionuclide inventories, midden and marine-shell deposits, relict soil properties, airborne and ground-based light detection and ranging (lidar) data, ranching artifacts, and historic records. Shortly after the introduction of sheep in 1853, localized sedimentation rates on the Pozo floodplain increased by two orders of magnitude from 0.4 mm/year to 25 mm/year. Accelerated sedimentation was followed by arroyo formation ca. 1878 and rapid expansion of the incipient gully network, the lateral extent of which has been largely maintained since 1929. Catchment-mean erosion rates from cosmogenic radionuclide measurements indicate that presettlement rates were less than 0.08 mm/year, whereas lidar-derived measurements of historic gully erosion produce estimates almost thirty times higher (2.2 mm/year). Topographic measurements since 2005 indicate that the active channel of the Pozo watershed is aggrading. We argue that accelerated sedimentation due to overgrazing, and an unusually large 1878 rainstorm event, set the stage for arroyo formation in the Pozo watershed between 1875 and 1886. We hypothesize that even in the absence of modern human disturbance, downcutting would have occurred due to intrinsic hillslope stability thresholds.” Ryan L. Perroy, Bodo Bookhagen, Oliver A. Chadwick & Jeffrey T. Howarth, Annals of the Association of American Geographers, Volume 102, Issue 6, 2012, DOI:10.1080/00045608.2012.715054.

Cause of the chalcophile trace element enrichments marking the Holocene to Anthropocene transition in northern Chesapeake Bay sediments – Dolor et al. (2012) “In Chesapeake Bay sediments, concentrations of 15 chalcophile trace elements, half rarely determined in estuaries, display historical profiles having remarkably similar features. All element concentrations rose more or less simultaneously in the 1920–1940 interval, creating a chemostratigraphic marker of the Holocene to Anthropocene transition. Subsequently, concentration maxima occurred at ∼20-year intervals, suggesting a link to a documented climate cycle of similar period. These elements’ correlated profiles suggest that sediments approximate binary mixtures of one lithogenic and one multi-element anthropogenic component. The latter component is characterized by these mass ratios (±standard error): [View Within Article]. Where comparisons are possible, these ratios differ from those of contaminants in the harbor of the region’s principal industrial city, Baltimore, but are surprisingly similar to those in sediment contaminants from the Susquehanna River, the Bay’s chief tributary. Thus both the anthropogenic and the lithogenic components in the Bay’s central channel appear to originate in the river basin. Many chalcophile element ratios in the anthropogenic component are similar to those in regional aerosols. If cumulative aerosol deposition on soils in the river basin is the source of the anthropogenic component, then the above ratios could be a regional anthropogenic signature that should be looked for more widely. Unlike Mo, the enrichment of these chalcophile elements in the Bay’s sediments is not controlled by seasonal anoxia; Mo apparently possesses a unique capacity to record past redox information about estuaries owing to its high seawater concentration.” Marvourneen K. Dolor, George R. Helz, William F. McDonough, Geochimica et Cosmochimica Acta, Volume 82, 1 April 2012, Pages 79–91, http://dx.doi.org/10.1016/j.gca.2010.06.040.

Is the Anthropocene an issue of stratigraphy or pop culture? – Autin & Holbrook (2012) “The term Anthropocene recently entered into the rhetoric of both the scientific community and the popular environmental movement. Scientific proponents argue that global industrialization drives accelerated Earth-system changes unrivaled in Earth’s history. The discussion now filters into geological stratigraphy with proposals to amend formal time stratigraphic nomenclature (Zalasiewicz et al., 2008, 2010). Environmentalists suggest that terms like Anthropocene foster broad social and cultural awareness of human-induced environmental changes. Advocates argue that greater awareness of humanity’s role in environmental change encourages sustainable resource utilization. Formal recognition of a new geologic epoch helps the broader scientific community solidify the idea of humanity as an Earth-system driver. Before the scientific community ventures too far, we wish to offer comment that considers the practicality of the Anthropocene to geological stratigraphy, the science to which it ultimately applies.” Whitney J. Autin, John M. Holbrook, GSA Today, Volume 22 Issue 7 (July 2012). [Full text]

The Anthropocene: a new epoch of geological time? – Zalasiewicz et al. (2011) “Anthropogenic changes to the Earth’s climate, land, oceans and biosphere are now so great and so rapid that the concept of a new geological epoch defined by the action of humans, the Anthropocene, is widely and seriously debated. Questions of the scale, magnitude and significance of this environmental change, particularly in the context of the Earth’s geological history, provide the basis for this Theme Issue. The Anthropocene, on current evidence, seems to show global change consistent with the suggestion that an epoch-scale boundary has been crossed within the last two centuries.” Jan Zalasiewicz, Mark Williams, Alan Haywood and Michael Ellis, Phil. Trans. R. Soc. A 13 March 2011 vol. 369 no. 1938 835-841, doi: 10.1098/rsta.2010.0339. [Full text]

The New World of the Anthropocene – Zalasiewicz et al. (2010) “The Anthropocene, following the lost world of the Holocene, holds challenges for both science and society.” Jan Zalasiewicz, Mark Williams, Will Steffen, Paul Crutzen, Environ. Sci. Technol., 2010, 44 (7), pp 2228–2231, DOI: 10.1021/es903118j. [Full text]

Are we now living in the Anthropocene? – Zalasiewicz et al. (2008) “The term Anthropocene, proposed and increasingly employed to denote the current interval of anthropogenic global environmental change, may be discussed on stratigraphic grounds. A case can be made for its consideration as a formal epoch in that, since the start of the Industrial Revolution, Earth has endured changes sufficient to leave a global stratigraphic signature distinct from that of the Holocene or of previous Pleistocene interglacial phases, encompassing novel biotic, sedimentary, and geochemical change. These changes, although likely only in their initial phases, are sufficiently distinct and robustly established for suggestions of a Holocene–Anthropocene boundary in the recent historical past to be geologically reasonable. The boundary may be defined either via Global Stratigraphic Section and Point (“golden spike”) locations or by adopting a numerical date. Formal adoption of this term in the near future will largely depend on its utility, particularly to earth scientists working on late Holocene successions. This datum, from the perspective of the far future, will most probably approximate a distinctive stratigraphic boundary.” Jan Zalasiewicz, Mark Williams, Alan Smith, Tiffany L. Barry, Angela L. Coe, Paul R. Bown, Patrick Brenchley, David Cantrill, Andrew Gale, Philip Gibbard, F. John Gregory, Mark W. Hounslow, Andrew C. Kerr, Paul Pearson, Robert Knox, John Powell, Colin Waters, John Marshall, Michael Oates, Peter Rawson, and Philip Stone, GSA Today 18 (2): 4-8, 1 Feb 2008. [Full text]

The Anthropocene: Are Humans Now Overwhelming the Great Forces of Nature – Steffen et al. (2007) “We explore the development of the Anthropocene, the current epoch in which humans and our societies have become a global geophysical force. The Anthropocene began around 1800 with the onset of industrialization, the central feature of which was the enormous expansion in the use of fossil fuels. We use atmospheric carbon dioxide concentration as a single, simple indicator to track the progression of the Anthropocene. From a preindustrial value of 270–275 ppm, atmospheric carbon dioxide had risen to about 310 ppm by 1950. Since then the human enterprise has experienced a remarkable explosion, the Great Acceleration, with significant consequences for Earth System functioning. Atmospheric CO₂ concentration has risen from 310 to 380 ppm since 1950, with about half of the total rise since the preindustrial era occurring in just the last 30 years. The Great Acceleration is reaching criticality. Whatever unfolds, the next few decades will surely be a tipping point in the evolution of the Anthropocene.” Will Steffen, Paul J. Crutzen, John R. McNeill, AMBIO: A Journal of the Human Environment 36(8):614-621. 2007, doi: http://dx.doi.org/10.1579/0044-7447(2007)36%5B614:TAAHNO%5D2.0.CO;2.

Humans as geologic agents: A deep-time perspective – Wilkinson (2005) “Humans move increasingly large amounts of rock and sediment during various construction activities, and mean rates of cropland soil loss may exceed rates of formation by up to an order of magnitude, but appreciating the actual importance of humans as agents of global erosion necessitates knowledge of prehistoric denudation rates imposed on land surfaces solely by natural processes. Amounts of weathering debris that compose continental and oceanic sedimentary rocks provide one such source of information and indicate that mean denudation over the past half-billion years of Earth history has lowered continental surfaces by a few tens of meters per million years. In comparison, construction and agricultural activities currently result in the transport of enough sediment and rock to lower all ice-free continental surfaces by a few hundred meters per million years. Humans are now an order of magnitude more important at moving sediment than the sum of all other natural processes operating on the surface of the planet. Relationships between temporal trends in land use and global population indicate that humans became the prime agents of erosion sometime during the latter part of the first millennium A.D.” Bruce H. Wilkinson, Geology, v. 33 no. 3 p. 161-164, doi: 10.1130/G21108.1. [Full text]

Fluvial filtering of land-to-ocean fluxes: from natural Holocene variations to Anthropocene – Meybeck & Vörösmarty (2005) “The evolution of river systems and their related fluxes is considered at various time scales: (i) over the last 18 000 years, under climatic variability control, (ii) over the last 50 to 200 years (Anthropocene) due to direct human impacts. Natural Holocene variations in time and space depend on (i) land-to-ocean connections (endorheism, glacial cover, exposure of continental shelf); (ii) types of natural fluvial filters (e.g., wetlands, lakes, floodplains, estuaries). Anthropocene changes concern (i) land–ocean connection (e.g., partial to total runoff reduction resulting from water management), (ii) modification and removal of natural filters, (iii) creation of new filters, particularly irrigated fields and reservoirs, (iv) acceleration and/or development of material sources from human activities. The total river basin area directly affected by human activities is of the same order of magnitude (>40 Mkm2) as the total area affected over the last 18 000 years. A tentative analysis of 38 major river systems totaling 55 Mkm2 is proposed for several criteria: (i) trajectories of Holocene evolution, (ii) occurrence of natural fluvial filters, (iii) present-day fluvial filters: most river basins are unique. Riverine fluxes per unit area are characterized by hot spots that exceed the world average by one order of magnitude. At the Anthropocene (i.e., since 1950), many riverine fluxes have globally increased (sodium, chloride, sulfate, nitrogen, phosphorous, heavy metals), others are stable (calcium, bicarbonate, sediments) or likely to decrease (dissolved silica). Future trajectories of river fluxes will depend on the balance between increased sources of material (e.g., soil erosion, pollution, fertilization), water abstraction for irrigation and the modification of fluvial filters, particularly the occurrence of reservoirs that already intercept half of the water and store at least 30% of river sediment fluxes. In some river systems, retention actually exceeds material production and river fluxes are actually decreasing. These trajectories are specific to each river and to each type of river material. Megacities, mining and industrial districts can be considered as hot spots of contaminants fluxes, while major reservoirs are global-scale sinks for all particulates. Global picture should therefore be determined at a fine resolution, since regional differences in Anthropocene evolution of river fluxes may reach one order of magnitude, as illustrated for total nitrogen.” Michel Meybeck, Charles Vörösmarty, Comptes Rendus Geoscience, Volume 337, Issues 1–2, January–February 2005, Pages 107–123, http://dx.doi.org/10.1016/j.crte.2004.09.016.

Global analysis of river systems: from Earth system controls to Anthropocene syndromes – Meybeck (2003) “Continental aquatic systems from rivers to the coastal zone are considered within two perspectives: (i) as a major link between the atmosphere, pedosphere, biosphere and oceans within the Earth system with its Holocene dynamics, and (ii) as water and aquatic biota resources progressively used and transformed by humans. Human pressures have now reached a state where the continental aquatic systems can no longer be considered as being controlled by only Earth system processes, thus defining a new era, the Anthropocene. Riverine changes, now observed at the global scale, are described through a first set of syndromes (flood regulation, fragmentation, sediment imbalance, neo–arheism, salinization, chemical contamination, acidification, eutrophication and microbial contamination) with their related causes and symptoms. These syndromes have direct influences on water uses, either positive or negative. They also modify some Earth system key functions such as sediment, water, nutrient and carbon balances, greenhouse gas emissions and aquatic biodiversity. Evolution of river syndromes over the past 2000 years is complex: it depends upon the stages of regional human development and on natural conditions, as illustrated here for the chemical contamination syndrome. River damming, eutrophication and generalized decrease of river flow due to irrigation are some of the other global features of river changes. Future management of river systems should also consider these long–term impacts on the Earth system.” Michel Meybeck, Phil. Trans. R. Soc. Lond. B 29 December 2003 vol. 358 no. 1440 1935-1955, doi: 10.1098/rstb.2003.1379. [Full text]

Geology of mankind – Crutzen (2002) “For the past three centuries, the effects of humans on the global environment have escalated. Because of these anthropogenic emissions of carbon dioxide, global climate may depart significantly from natural behaviour for many millennia to come. It seems appropriate to assign the term ‘Anthropocene’ to the present, in many ways human-dominated, geological epoch, supplementing the Holocene — the warm period of the past 10–12 millennia. The Anthropocene could be said to have started in the latter part of the eighteenth century, when analyses of air trapped in polar ice showed the beginning of growing global concentrations of carbon dioxide and methane.” Paul J. Crutzen, Nature 415, 23 (3 January 2002) | doi:10.1038/415023a. [Full text]

On the history of humans as geomorphic agents – Hooke (2000) “The human population has been increasing exponentially. Simultaneously, as digging sticks and antlers have given way to wooden plows, iron spades, steam shovels, and today’s huge excavators, our ability and motivation to modify the landscape by moving earth in construction and mining activities have also increased dramatically. As a consequence, we have now become arguably the premier geomorphic agent sculpting the landscape, and the rate at which we are moving earth is increasing exponentially. As hunter-gatherer cultures were replaced by agrarian societies to feed this expanding population, erosion from agricultural fields also, until recently, increased steadily. This constitutes an unintended additional human impact on the landscape.” Roger LeB. Hooke, Geology September, 2000 v. 28, no. 9, p. 843-846, doi: 10.1130/​0091-7613(2000)​28​2.0.CO;2. [Full text]

L’éxigence idéaliste et le fait de l’évolution – Le Roy (1927) A book where term “Noosphere” is used for Anthropocene. E. W. Berry, Science, New Series, Vol. 64, No. 1644 (Jul. 2, 1926), p. 16, DOI: 10.2307/1651728.

The Term Psychozoic – Berry (1926) No abstract. E. W. Berry, Science, New Series, Vol. 64, No. 1644 (Jul. 2, 1926), p. 16, DOI: 10.2307/1651728.

Elements of Geology – Le Conte (1879) A book where term “Psychozoic” is used for Anthropocene. Le Conte, J. Elements of Geology; D. Appleton & Co: New York, 1879. [Full text]

Corsa di Geologia – Stoppani (1873) A book where term “anthropozoic” is used for Anthropocene. From Crutzen (2002): “Mankind’s growing influence on the environment was recognized as long ago as 1873, when the Italian geologist Antonio Stoppani spoke about a “new telluric force which in power and universality may be compared to the greater forces of earth,” referring to the “anthropozoic era”.” Stoppani, A. Corsa di Geologia; Milan, 1873.

Papers on the role of the Sun in recent global warming

This list contains papers that on Sun’s role in the recent climate change. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative. Generally no papers simply reporting solar activity measurements are included (those papers will get their own list in future) or other solar activity related papers that do not discuss recent climate change. Also indirect solar effects are mainly left to their own lists (for example through geomagnetism). There already are separate lists for solar cycle length and cosmic rays.

Evidence of recent causal decoupling between solar radiation and global temperature – Pasini et al. (2012) “The Sun has surely been a major external forcing to the climate system throughout the Holocene. Nevertheless, opposite trends in solar radiation and temperatures have been empirically identified in the last few decades. Here, by means of an inferential method—the Granger causality analysis—we analyze this situation and, for the first time, show that an evident causal decoupling between total solar irradiance and global temperature has appeared since the 1960s.” Antonello Pasini et al 2012 Environ. Res. Lett. 7 034020 doi:10.1088/1748-9326/7/3/034020. [Full text]

Solar Influence on Global and Regional Climates – Lockwood (2012) “The literature relevant to how solar variability influences climate is vast—but much has been based on inadequate statistics and non-robust procedures. The common pitfalls are outlined in this review. The best estimates of the solar influence on the global mean air surface temperature show relatively small effects, compared with the response to anthropogenic changes (and broadly in line with their respective radiative forcings). However, the situation is more interesting when one looks at regional and season variations around the global means. In particular, recent research indicates that winters in Eurasia may have some dependence on the Sun, with more cold winters occurring when the solar activity is low. Advances in modelling “top-down” mechanisms, whereby stratospheric changes influence the underlying troposphere, offer promising explanations of the observed phenomena. In contrast, the suggested modulation of low-altitude clouds by galactic cosmic rays provides an increasingly inadequate explanation of observations.” Mike Lockwood, Surveys in Geophysics, July 2012, Volume 33, Issue 3-4, pp 503-534. [Full text]

Solar Forcing of Climate – de Jager (2012) “Solar activity is evident both in the equatorial activity centres and in the polar magnetic field variations. The total solar irradiance variation is due to the former component. During the extraordinarily long minimum of activity between sunspot cycles 23 and 24, the variations related to the equatorial field components reached their minimum values in the first half of 2008, while those related to the polar field variations had their extreme values rather at the end of 2009 and the first half of 2010. The explanation of this delay is another challenge for dynamo theories. The role of the open solar flux has so far been grossly underestimated in discussions of Sun-climate relations. The gradual increase in the average terrestrial ground temperature since 1610 is related both to the equatorial and polar field variations. The main component (0.077 K/century) is due to the variation of the total solar irradiance. The second component (0.040 K/century) waits for an explanation. The smoothed residual increase, presumably antropogenic, obtained after subtraction of the known components from the total increase was 0.31 K in 1999.” C. de Jager, Surveys in Geophysics, July 2012, Volume 33, Issue 3-4, pp 445-451. [Full text]

Solar activity–climate relations: A different approach – Stauning (2011) “The presentation of solar activity–climate relations is extended with the most recent sunspot and global temperature data series. The extension of data series shows clearly that the changes in terrestrial temperatures are related to sources different from solar activity after ∼1985. Based on analyses of data series for the years 1850–1985 it is demonstrated that, apart from an interval of positive deviation followed by a similar negative excursion in Earth’s temperatures between ∼1923 and 1965, there is a strong correlation between solar activity and terrestrial temperatures delayed by 3 years, which complies with basic causality principles. A regression analysis between solar activity represented by the cycle-average sunspot number, SSN_A, and global temperature anomalies, ΔT_A, averaged over the same interval lengths, but delayed by 3 years, provides the relation ΔT_A∼0.009 (±0.002) SSN_A. Since the largest ever observed SSN_A is ∼90 (in 1954–1965), the solar activity-related changes in global temperatures could amount to no more than ±0.4 °C over the past ∼400 years where the sunspots have been recorded. It is demonstrated that the small amplitudes of cyclic variations in the average global temperatures over the ∼11 year solar cycle excludes many of the various driver processes suggested in published and frequently quoted solar activity–climate relations. It is suggested that the in-cycle variations and also the longer term variations in global temperatures over the examined 135 years are mainly caused by corresponding changes in the total solar irradiance level representing the energy output from the core, but further modulated by varying energy transmission properties in the active outer regions of the Sun.” P. Stauning, Journal of Atmospheric and Solar-Terrestrial Physics, Volume 73, Issue 13, August 2011, Pages 1999–2012, http://dx.doi.org/10.1016/j.jastp.2011.06.011.

Are secular correlations between sunspots, geomagnetic activity, and global temperature significant? – Love et al. (2011) “Recent studies have led to speculation that solar-terrestrial interaction, measured by sunspot number and geomagnetic activity, has played an important role in global temperature change over the past century or so. We treat this possibility as an hypothesis for testing. We examine the statistical significance of cross-correlations between sunspot number, geomagnetic activity, and global surface temperature for the years 1868–2008, solar cycles 11–23. The data contain substantial autocorrelation and nonstationarity, properties that are incompatible with standard measures of cross-correlational significance, but which can be largely removed by averaging over solar cycles and first-difference detrending. Treated data show an expected statistically-significant correlation between sunspot number and geomagnetic activity, Pearson p < 10−4, but correlations between global temperature and sunspot number (geomagnetic activity) are not significant, p = 0.9954, (p = 0.8171). In other words, straightforward analysis does not support widely-cited suggestions that these data record a prominent role for solar-terrestrial interaction in global climate change. With respect to the sunspot-number, geomagnetic-activity, and global-temperature data, three alternative hypotheses remain difficult to reject: (1) the role of solar-terrestrial interaction in recent climate change is contained wholly in long-term trends and not in any shorter-term secular variation, or, (2) an anthropogenic signal is hiding correlation between solar-terrestrial variables and global temperature, or, (3) the null hypothesis, recent climate change has not been influenced by solar-terrestrial interaction.” Love, J. J., K. Mursula, V. C. Tsai, and D. M. Perkins (2011), Geophys. Res. Lett., 38, L21703, doi:10.1029/2011GL049380. [Full text]

Solar influences on climate – Gray et al. (2010) “Understanding the influence of solar variability on the Earth’s climate requires knowledge of solar variability, solar-terrestrial interactions, and the mechanisms determining the response of the Earth’s climate system. We provide a summary of our current understanding in each of these three areas. Observations and mechanisms for the Sun’s variability are described, including solar irradiance variations on both decadal and centennial time scales and their relation to galactic cosmic rays. Corresponding observations of variations of the Earth’s climate on associated time scales are described, including variations in ozone, temperatures, winds, clouds, precipitation, and regional modes of variability such as the monsoons and the North Atlantic Oscillation. A discussion of the available solar and climate proxies is provided. Mechanisms proposed to explain these climate observations are described, including the effects of variations in solar irradiance and of charged particles. Finally, the contributions of solar variations to recent observations of global climate change are discussed.” Gray, L. J., et al. (2010), SOLAR INFLUENCES ON CLIMATE, Rev. Geophys., 48, RG4001, doi:10.1029/2009RG000282. [Full text]

An influence of solar spectral variations on radiative forcing of climate – Haigh et al. (2010) “The thermal structure and composition of the atmosphere is determined fundamentally by the incoming solar irradiance. Radiation at ultraviolet wavelengths dissociates atmospheric molecules, initiating chains of chemical reactions—specifically those producing stratospheric ozone—and providing the major source of heating for the middle atmosphere, while radiation at visible and near-infrared wavelengths mainly reaches and warms the lower atmosphere and the Earth’s surface. Thus the spectral composition of solar radiation is crucial in determining atmospheric structure, as well as surface temperature, and it follows that the response of the atmosphere to variations in solar irradiance depends on the spectrum. Daily measurements of the solar spectrum between 0.2 µm and 2.4 µm, made by the Spectral Irradiance Monitor (SIM) instrument on the Solar Radiation and Climate Experiment (SORCE) satellite since April 2004, have revealed that over this declining phase of the solar cycle there was a four to six times larger decline in ultraviolet than would have been predicted on the basis of our previous understanding. This reduction was partially compensated in the total solar output by an increase in radiation at visible wavelengths. Here we show that these spectral changes appear to have led to a significant decline from 2004 to 2007 in stratospheric ozone below an altitude of 45 km, with an increase above this altitude. Our results, simulated with a radiative-photochemical model, are consistent with contemporaneous measurements of ozone from the Aura-MLS satellite, although the short time period makes precise attribution to solar effects difficult. We also show, using the SIM data, that solar radiative forcing of surface climate is out of phase with solar activity. Currently there is insufficient observational evidence to validate the spectral variations observed by SIM, or to fully characterize other solar cycles, but our findings raise the possibility that the effects of solar variability on temperature throughout the atmosphere may be contrary to current expectations.” Joanna D. Haigh, Ann R. Winning, Ralf Toumi & Jerald W. Harder, Nature, Volume: 467, Pages: 696–699, Date published: 07 October 2010, doi:10.1038/nature09426. [Full text]

Solar change and climate: an update in the light of the current exceptional solar minimum – Lockwood (2010) “Solar outputs during the current solar minimum are setting record low values for the space age. Evidence is here reviewed that this is part of a decline in solar activity from a grand solar maximum and that the Sun has returned to a state that last prevailed in 1924. Recent research into what this means, and does not mean, for climate change is reviewed.” Mike Lockwood, Proc. R. Soc. A 8 February 2010 vol. 466 no. 2114 303-329, doi: 10.1098/rspa.2009.0519. [Full text]

Cycles and trends in solar irradiance and climate – Lean (2010) “How—indeed whether—the Sun’s variable energy outputs influence Earth’s climate has engaged scientific curiosity for more than a century. Early evidence accrued from correlations of assorted solar and climate indices, and from recognition that cycles near 11, 88 and 205 years are common in both the Sun and climate. But until recently, an influence of solar variability on climate, whether through cycles or trends, was usually dismissed because climate simulations with (primarily) simple energy balance models indicated that responses to the decadal solar cycle would be so small as to be undetectable in observations. However, in the past decade modeling studies have found both resonant responses and positive feedbacks in the ocean‐atmosphere system that may amplify the response to solar irradiance variations. Today, solar cycles and trends are recognized as important components of natural climate variability on decadal to centennial time scales. Understanding solar‐terrestrial linkages is requisite for the comprehensive understanding of Earth’s evolving environment. The attribution of present‐day climate change, interpretation of changes prior to the industrial epoch, and forecast of future decadal climate change necessitate quantitative understanding of how, when, where, and why natural variability, including by the Sun, may exceed, obscure or mitigate anthropogenic changes.” Judith L. Lean, Wiley Interdisciplinary Reviews: Climate Change, 1, 1, 111-122, DOI: 10.1002/wcc.18. [Full text]

Solar trends and global warming – Benestad & Schmidt (2009) “We use a suite of global climate model simulations for the 20th century to assess the contribution of solar forcing to the past trends in the global mean temperature. In particular, we examine how robust different published methodologies are at detecting and attributing solar-related climate change in the presence of intrinsic climate variability and multiple forcings. We demonstrate that naive application of linear analytical methods such as regression gives nonrobust results. We also demonstrate that the methodologies used by Scafetta and West (2005, 2006a, 2006b, 2007, 2008) are not robust to these same factors and that their error bars are significantly larger than reported. Our analysis shows that the most likely contribution from solar forcing a global warming is 7 ± 1% for the 20th century and is negligible for warming since 1980.” Benestad, R. E. and G. A. Schmidt (2009), Solar trends and global warming, J. Geophys. Res., 114, D14101, doi:10.1029/2008JD011639. [Full text]

Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise – Lockwood (2008) “A multivariate fit to the variation in global mean surface air temperature anomaly over the past half century is presented. The fit procedure allows for the effect of response time on the waveform, amplitude and lag of each radiative forcing input, and each is allowed to have its own time constant. It is shown that the contribution of solar variability to the temperature trend since 1987 is small and downward; the best estimate is −1.3% and the 2σ confidence level sets the uncertainty range of −0.7 to −1.9%. The result is the same if one quantifies the solar variation using galactic cosmic ray fluxes (for which the analysis can be extended back to 1953) or the most accurate total solar irradiance data composite. The rise in the global mean air surface temperatures is predominantly associated with a linear increase that represents the combined effects of changes in anthropogenic well-mixed greenhouse gases and aerosols, although, in recent decades, there is also a considerable contribution by a relative lack of major volcanic eruptions. The best estimate is that the anthropogenic factors contribute 75% of the rise since 1987, with an uncertainty range (set by the 2σ confidence level using an AR(1) noise model) of 49–160%; thus, the uncertainty is large, but we can state that at least half of the temperature trend comes from the linear term and that this term could explain the entire rise. The results are consistent with the intergovernmental panel on climate change (IPCC) estimates of the changes in radiative forcing (given for 1961–1995) and are here combined with those estimates to find the response times, equilibrium climate sensitivities and pertinent heat capacities (i.e. the depth into the oceans to which a given radiative forcing variation penetrates) of the quasi-periodic (decadal-scale) input forcing variations. As shown by previous studies, the decadal-scale variations do not penetrate as deeply into the oceans as the longer term drifts and have shorter response times. Hence, conclusions about the response to century-scale forcing changes (and hence the associated equilibrium climate sensitivity and the temperature rise commitment) cannot be made from studies of the response to shorter period forcing changes.” Mike Lockwood, Proc. R. Soc. A 8 June 2008 vol. 464 no. 2094 1387-1404, doi: 10.1098/rspa.2007.0348. [Full text]

Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. II. Different reconstructions of the total solar irradiance variation and dependence on response time scale – Lockwood & Fröhlich (2008) “We have previously placed the solar contribution to recent global warming in context using observations and without recourse to climate models. It was shown that all solar forcings of climate have declined since 1987. The present paper extends that analysis to include the effects of the various time constants with which the Earth’s climate system might react to solar forcing. The solar input waveform over the past 100 years is defined using observed and inferred galactic cosmic ray fluxes, valid for either a direct effect of cosmic rays on climate or an effect via their known correlation with total solar irradiance (TSI), or for a combination of the two. The implications, and the relative merits, of the various TSI composite data series are discussed and independent tests reveal that the PMOD composite used in our previous paper is the most realistic. Use of the ACRIM composite, which shows a rise in TSI over recent decades, is shown to be inconsistent with most published evidence for solar influences on pre-industrial climate. The conclusions of our previous paper, that solar forcing has declined over the past 20 years while surface air temperatures have continued to rise, are shown to apply for the full range of potential time constants for the climate response to the variations in the solar forcings.” Mike Lockwood and Claus Fröhlich, Proc. R. Soc. A 8 June 2008 vol. 464 no. 2094 1367-1385, doi: 10.1098/rspa.2007.0347. [Full text]

Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature – Lockwood & Fröhlich (2007) “There is considerable evidence for solar influence on the Earth’s pre-industrial climate and the Sun may well have been a factor in post-industrial climate change in the first half of the last century. Here we show that over the past 20 years, all the trends in the Sun that could have had an influence on the Earth’s climate have been in the opposite direction to that required to explain the observed rise in global mean temperatures.” Mike Lockwood and Claus Fröhlich, Proc. R. Soc. A 8 October 2007 vol. 463 no. 2086 2447-2460, doi: 10.1098/rspa.2007.1880. [Full text]

Variations in solar luminosity and their effect on the Earth’s climate – Foukal et al. (2006) “Variations in the Sun’s total energy output (luminosity) are caused by changing dark (sunspot) and bright structures on the solar disk during the 11-year sunspot cycle. The variations measured from spacecraft since 1978 are too small to have contributed appreciably to accelerated global warming over the past 30 years. In this Review, we show that detailed analysis of these small output variations has greatly advanced our understanding of solar luminosity change, and this new understanding indicates that brightening of the Sun is unlikely to have had a significant influence on global warming since the seventeenth century. Additional climate forcing by changes in the Sun’s output of ultraviolet light, and of magnetized plasmas, cannot be ruled out. The suggested mechanisms are, however, too complex to evaluate meaningfully at present.” P. Foukal, C. Fröhlich, H. Spruit and T. M. L. Wigley, Nature 443, 161-166 (14 September 2006) | doi:10.1038/nature05072. [Full text]

Phenomenological solar contribution to the 1900–2000 global surface warming – Scafetta & West (2006) “We study the role of solar forcing on global surface temperature during four periods of the industrial era (1900–2000, 1900–1950, 1950–2000 and 1980–2000) by using a sun-climate coupling model based on four scale-dependent empirical climate sensitive parameters to solar variations. We use two alternative total solar irradiance satellite composites, ACRIM and PMOD, and a total solar irradiance proxy reconstruction. We estimate that the sun contributed as much as 45–50% of the 1900–2000 global warming, and 25–35% of the 1980–2000 global warming. These results, while confirming that anthropogenic-added climate forcing might have progressively played a dominant role in climate change during the last century, also suggest that the solar impact on climate change during the same period is significantly stronger than what some theoretical models have predicted.” Scafetta, N. and B. J. West (2006), Phenomenological solar contribution to the 1900–2000 global surface warming, Geophys. Res. Lett., 33, L05708, doi:10.1029/2005GL025539. [Full text]

Measurement and Uncertainty of the Long-Term Total Solar Irradiance Trend – Dewitte et al. (2005) “A possible long-term trend of the total solar irradiance could be a natural cause for climate variations on Earth. Measurement of the total solar irradiance with space radiometers started in 1978. We present a new total solar irradiance composite, with an uncertainty of ± 0.35 W m⁻². From the minimum in 1995 to the maximum in 2002 the total solar irradiance increased by 1.6 W m⁻². In between the minima of 1987 and 1995 the total solar irradiance increased by 0.15 W m⁻².” Steven Dewitte, Dominique Crommelynck, Sabri Mekaoui, Alexandre Joukoff, Solar Physics, October 2004, Volume 224, Issue 1-2, pp 209-216, DOI: 10.1007/s11207-005-5698-7. [Full text]

Total solar irradiance and climate – Mendoza (2005) “The solar radiation is the fundamental source of energy that drives the Earth’s climate and sustains life. The variability of this output certainly affects our planet. In the last two decades an enormous advance in the understanding of the variability of the solar irradiance has been achieved. Space-based measurements indicate that the total solar irradiance changes at various time scales, from minutes to the solar cycle. Climate models show that total solar irradiance variations can account for a considerable part of the temperature variation of the Earth’s atmosphere in the pre-industrial era. During the 20th century its relative influence on the temperature changes has descended considerably. This means that other sources of solar activity as well as internal and man-made causes are contributing to the Earth’s temperature variability, particularly the former in the 20th century. Some very challenging questions concerning total solar irradiance variations and climate have been raised: are total solar irradiance variations from cycle to cycle well represented by sunspot and facular changes? Does total solar irradiance variations always parallel the solar activity cycle? Is there a long-term variation of the total solar irradiance, and closely related to this, is the total solar irradiance output of the quiet sun constant? If there is not a long-term trend of total solar irradiance variations, then we need amplifying mechanisms of total solar irradiance to account for the good correlations found between total solar irradiance and climate. The latter because the observed total solar irradiance changes are inconsequential when introduced in present climate models.” Blanca Mendoza, Advances in Space Research, Volume 35, Issue 5, 2005, Pages 882–890, http://dx.doi.org/10.1016/j.asr.2004.10.011. [Full text]

How unusual is today’s solar activity? (reply) – Solanki et al. (2005) “Muscheler et al. claim that the solar activity affecting cosmic rays was much higher in the past than we deduced from ¹⁴C measurements. However, this claim is based on a problematic normalization and is in conflict with independent results, such as the ⁴⁴Ti activity in meteorites and the ¹⁰Be concentration in ice cores.” S. K. Solanki, I. G. Usoskin, B. Kromer, M. Schüssler & J. Beer, Nature 436, E4-E5 (28 July 2005) | doi:10.1038/nature04046.

How unusual is today’s solar activity? – Muscheler et al. (2005) “To put global warming into context requires knowledge about past changes in solar activity and the role of the Sun in climate change. Solanki et al. propose that solar activity during recent decades was exceptionally high compared with that over the preceding 8,000 years. However, our extended analysis of the radiocarbon record reveals several periods during past centuries in which the strength of the magnetic field in the solar wind was similar to, or even higher than, that of today.” Raimund Muscheler, Fortunat Joos, Simon A. Müller & Ian Snowball, Nature 436, E3-E4 (28 July 2005) | doi:10.1038/nature04045.

Unusual activity of the Sun during recent decades compared to the previous 11,000 years – Solanki et al. (2004) “Direct observations of sunspot numbers are available for the past four centuries, but longer time series are required, for example, for the identification of a possible solar influence on climate and for testing models of the solar dynamo. Here we report a reconstruction of the sunspot number covering the past 11,400 years, based on dendrochronologically dated radiocarbon concentrations. We combine physics-based models for each of the processes connecting the radiocarbon concentration with sunspot number. According to our reconstruction, the level of solar activity during the past 70 years is exceptional, and the previous period of equally high activity occurred more than 8,000 years ago. We find that during the past 11,400 years the Sun spent only of the order of 10% of the time at a similarly high level of magnetic activity and almost all of the earlier high-activity periods were shorter than the present episode. Although the rarity of the current episode of high average sunspot numbers may indicate that the Sun has contributed to the unusual climate change during the twentieth century, we point out that solar variability is unlikely to have been the dominant cause of the strong warming during the past three decades.” S. K. Solanki, I. G. Usoskin, B. Kromer, M. Schüssler & J. Beer, Nature 431, 1084-1087 (28 October 2004) | doi:10.1038/nature02995.

Can solar variability explain global warming since 1970? – Solanki & Krivova (2003) “The magnitude of the Sun’s influence on climate has been a subject of intense debate. Estimates of this magnitude are generally based on assumptions regarding the forcing due to solar irradiance variations and climate modeling. This approach suffers from uncertainties that are difficult to estimate. Such uncertainties are introduced because the employed models may not include important but complex processes or mechanisms or may treat these in too simplified a manner. Here we take a more empirical approach. We employ time series of the most relevant solar quantities, the total and UV irradiance between 1856 and 1999 and the cosmic rays flux between 1868 and 1999. The time series are constructed using direct measurements wherever possible and reconstructions based on models and proxies at earlier times. These time series are compared with the climate record for the period 1856 to 1970. The solar records are scaled such that statistically the solar contribution to climate is as large as possible in this period. Under this assumption we repeat the comparison but now including the period 1970–1999. This comparison shows without requiring any recourse to modeling that since roughly 1970 the solar influence on climate (through the channels considered here) cannot have been dominant. In particular, the Sun cannot have contributed more than 30% to the steep temperature increase that has taken place since then, irrespective of which of the three considered channels is the dominant one determining Sun-climate interactions: tropospheric heating caused by changes in total solar irradiance, stratospheric chemistry influenced by changes in the solar UV spectrum, or cloud coverage affected by the cosmic ray flux.” Solanki, S. K. and N. A. Krivova (2003), Can solar variability explain global warming since 1970?, J. Geophys. Res., 108(A5), 1200, doi:10.1029/2002JA009753. [Full text]

Do Models Underestimate the Solar Contribution to Recent Climate Change? – Stott et al. (2003) “Current attribution analyses that seek to determine the relative contributions of different forcing agents to observed near-surface temperature changes underestimate the importance of weak signals, such as that due to changes in solar irradiance. Here a new attribution method is applied that does not have a systematic bias against weak signals. It is found that current climate models underestimate the observed climate response to solar forcing over the twentieth century as a whole, indicating that the climate system has a greater sensitivity to solar forcing than do models. The results from this research show that increases in solar irradiance are likely to have had a greater influence on global-mean temperatures in the first half of the twentieth century than the combined effects of changes in anthropogenic forcings. Nevertheless the results confirm previous analyses showing that greenhouse gas increases explain most of the global warming observed in the second half of the twentieth century.” Stott, Peter A., Gareth S. Jones, John F. B. Mitchell, 2003: Do Models Underestimate the Solar Contribution to Recent Climate Change?. J. Climate, 16, 4079–4093. doi: http://dx.doi.org/10.1175/1520-0442(2003)0162.0.CO;2. [Full text]

The Sun’s Role in Climate Variations – Rind (2002) A review paper. “Is the Sun the controller of climate changes, only the instigator of changes that are mostly forced by the system feedbacks, or simply a convenient scapegoat for climate variations lacking any other obvious cause? This question is addressed for suggested solar forcing mechanisms operating on time scales from billions of years to decades. Each mechanism fails to generate the expected climate response in important respects, although some relations are found. The magnitude of the system feedbacks or variability appears as large or larger than that of the solar forcing, making the Sun’s true role ambiguous. As the Sun provides an explicit external forcing, a better understanding of its cause and effect in climate change could help us evaluate the importance of other climate forcings (such as past and future greenhouse gas changes).” D. Rind, Science 26 April 2002: Vol. 296 no. 5568 pp. 673-677, DOI: 10.1126/science.1069562. [Full text]

The effects of solar variability on the Earth’s climate – Haigh (2002) A review paper. “The absolute value of total solar irradiance is not known to better than ca. 0.3% but measurements from satellite instruments over the past two solar cycles have shown that it varies by ca. 0.1% on this time-scale. Over longer periods its value has been reconstructed using proxy measures of solar activity, and these suggest that during the Maunder minimum in solar activity of the late 17th century it was 3-4 W m^-2 lower than at present. Observational data suggest that the Sun has influenced temperatures on decadal, centennial and millennial time-scales, but radiative forcing considerations and the results of energy-balance models and general circulation models suggest that the warming during the latter part of the 20th century cannot be ascribed entirely to solar effects. However, chemical and dynamical processes in the middle atmosphere may act to amplify the solar impact. An analysis of zonal mean temperature data shows that solar effects may be differentiated from those associated with other factors such as volcanic eruptions and the El Niño Southern Oscillation.” Joanna D. Haigh, Philosophical Transactions: Mathematical, Physical and Engineering Sciences, Vol. 361, No. 1802, Science and Applications of the Space Environment: New Results and Interdisciplinary Connections (Jan. 15, 2003), pp. 95-111. [Full text]

Solar Variability and the Earth’s Climate: Introduction and Overview – Reid (2000) “Numerous attempts have been made over the years to link various aspects of solar variability to changes in the Earth’s climate. There has been growing interest in this possible connection in recent years, spurred largely by the need to understand the natural causes of climate change, against which the expected global warming due to man’s activities will have to be detected. The time scale of concern here is that of decades to centuries, and excludes the longer millennial scale in which orbital variations play a dominant role. The field has long been plagued by the lack of an acceptable physical mechanism by which solar variability can affect climate, but the discovery of variability in the Sun’s total irradiance (the solar “constant” of meteorology) by spacecraft instruments has pointed to a direct mechanism. Other less direct mechanisms that have been suggested involve variations in the Sun’s ultraviolet flux and in the plasma outflow of the solar wind. The purpose of this paper is to summarize the current state of the field, emphasizing the proposed mechanisms as an introduction to the more detailed papers that follow. The particular case of sea-surface temperature data will be used as an illustration.” George C. Reid, Space Science Reviews, November 2000, Volume 94, Issue 1-2, pp 1-11, DOI: 10.1023/A:1026797127105.

The Sun’s total irradiance: Cycles, trends and related climate change uncertainties since 1976 – Fröhlich & Lean (1998) “A composite record of the Sun’s total irradiance compiled from measurements made by five independent space‐based radiometers since 1978 exhibits a prominent 11‐year cycle with similar levels during 1986 and 1996, the two most recent minimum epochs of solar activity. This finding contradicts recent assertions of a 0.04% irradiance increase from the 1986 to 1996 solar minima and suggests that solar radiative output trends contributed little of the 0.2°C increase in the global mean surface temperature in the past decade. Nor does our 18‐year composite irradiance record support a recent upward irradiance trend inferred from solar cycle length, a parameter used to imply a close linkage in the present century between solar variability and climate change.” Fröhlich, C. and J. Lean (1998), The Sun’s total irradiance: Cycles, trends and related climate change uncertainties since 1976, Geophys. Res. Lett., 25(23), 4377–4380, doi:10.1029/1998GL900157. [Full text]

Dependence of global temperatures on atmospheric CO₂ and solar irradiance – Thomson (1997) “Changes in global average temperatures and of the seasonal cycle are strongly coupled to the concentration of atmospheric CO₂. I estimate transfer functions from changes in atmospheric CO₂ and from changes in solar irradiance to hemispheric temperatures that have been corrected for the effects of precession. They show that changes from CO₂ over the last century are about three times larger than those from changes in solar irradiance. The increase in global average temperature during the last century is at least 20 times the SD of the residual temperature series left when the effects of CO₂ and changes in solar irradiance are subtracted.” David J. Thomson, PNAS August 5, 1997 vol. 94 no. 16 8370-8377. [Full text]

The Seasons, Global Temperature, and Precession – Thomson (1995) “Analysis of instrumental temperature records beginning in 1659 shows that in much of the world the dominant frequency of the seasons is one cycle per anomalistic year (the time from perihelion to perihelion, 365.25964 days), not one cycle per tropical year (the time from equinox to equinox, 365.24220 days), and that the timing of the annual temperature cycle is controlled by perihelion. The assumption that the seasons were timed by the equinoxes has caused many statistical analyses of climate data to be badly biased. Coherence between changes in the amplitude of the annual cycle and those in the average temperature show that between 1854 and 1922 there were small temperature variations, probably of solar origin. Since 1922, the phase of the Northern Hemisphere coherence between these quantities switched from 0° to 180° and implies that solar variability cannot be the sole cause of the increasing temperature over the last century. About 1940, the phase patterns of the previous 300 years began to change and now appear to be changing at an unprecedented rate. The average change in phase is now coherent with the logarithm of atmospheric CO2 concentration.” David J. Thomson, Science 7 April 1995: Vol. 268 no. 5207 pp. 59-68, DOI: 10.1126/science.268.5207.59.

New research from last week 52/2012

Here it is – the last post in the New research from last week series. I thank all researchers for providing continuous stream of interesting science to include to weekly batches. I also thank all readers for their interest in the series. New research reporting will continue in some form, which is currently uncertain. I probably will continue pointing out some interesting papers in my Twitter feed, but I expect that even there will be a quiet period in coming weeks. Happy new year for all climate science fans everywhere!

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Time-varying climate sensitivity from regional feedbacks

Time-varying climate sensitivity from regional feedbacks – Armour et al. (2012) [FULL TEXT]

Abstract: “The sensitivity of global climate with respect to forcing is generally described in terms of the global climate feedback—the global radiative response per degree of global annual mean surface temperature change. While the global climate feedback is often assumed to be constant, its value—diagnosed from global climate models—shows substantial time-variation under transient warming. Here we propose that a reformulation of the global climate feedback in terms of its contributions from regional climate feedbacks provides a clear physical insight into this behavior. Using (i) a state-of-the-art global climate model and (ii) a low-order energy balance model, we show that the global climate feedback is fundamentally linked to the geographic pattern of regional climate feedbacks and the geographic pattern of surface warming at any given time. Time-variation of the global climate feedback arises naturally when the pattern of surface warming evolves, actuating regional feedbacks of different strengths. This result has substantial implications for our ability to constrain future climate changes from observations of past and present climate states. The regional climate feedbacks formulation reveals fundamental biases in a widely-used method for diagnosing climate sensitivity, feedbacks and radiative forcing—the regression of the global top-of-atmosphere radiation flux on global surface temperature. Further, it suggests a clear mechanism for the ‘efficacies’ of both ocean heat uptake and radiative forcing.”

Citation: Kyle C. Armour, Cecilia M. Bitz, Gerard H. Roe, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00544.1.

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West Antarctic rapid glacier retreat may be exceptional during the Holocene

Grounding-line retreat of the West Antarctic Ice Sheet from inner Pine Island Bay – Hillenbrand et al. (2012)

Abstract: “Ice loss from the marine-based, potentially unstable West Antarctic Ice Sheet (WAIS) contributes to current sea-level rise and may raise sea level by ≤3.3 m or even ≤5 m in the future. Over the past few decades, glaciers draining the WAIS into the Amundsen Sea Embayment (ASE) have shown accelerated ice flow, rapid thinning, and fast retreat of the grounding line (GL). However, the long-term context of this ice loss is poorly constrained, limiting our ability to accurately predict future WAIS behavior. Here we present a new chronology for WAIS retreat from the inner continental shelf of the eastern ASE, based on radiocarbon dates from three marine sediment cores. The ages document a retreat of the GL to within ∼100 km of its modern position before ca. 10,000 calibrated (cal.) yr B.P. This early deglaciation is consistent with ages for GL retreat from the western ASE. Our new data demonstrate that, in contrast to the Ross Sea, WAIS retreat from the ASE shelf was largely complete by the start of the Holocene. Our results further suggest either slow GL retreat from the inner ASE shelf throughout the Holocene, or that any episodes of fast GL retreat must have been short-lived. Thus, today’s rapid retreat may be exceptional during the Holocene and may originate in recent changes in regional climate, ocean circulation, or ice-sheet dynamics.”

Citation: Claus-Dieter Hillenbrand, Gerhard Kuhn, James A. Smith, Karsten Gohl, Alastair G.C. Graham, Robert D. Larter, Johann P. Klages, Rachel Downey, Steven G. Moreton, Matthias Forwick and David G. Vaughan, Geology, v. 41 no. 1 p. 35-38, doi: 10.1130/G33469.1.

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Late Pleistocene tropical Pacific temperatures suggest higher climate sensitivity than currently thought

Late Pleistocene tropical Pacific temperature sensitivity to radiative greenhouse gas forcing – Dyez & Ravelo (2012)

Abstract: “Understanding how global temperature changes with increasing atmospheric greenhouse gas concentrations, or climate sensitivity, is of central importance to climate change research. Climate models provide sensitivity estimates that may not fully incorporate slow, long-term feedbacks such as those involving ice sheets and vegetation. Geological studies, on the other hand, can provide estimates that integrate long- and short-term climate feedbacks to radiative forcing. Because high latitudes are thought to be most sensitive to greenhouse gas forcing owing to, for example, ice-albedo feedbacks, we focus on the tropical Pacific Ocean to derive a minimum value for long-term climate sensitivity. Using Mg/Ca paleothermometry from the planktonic foraminifera Globigerinoides ruber from the past 500 k.y. at Ocean Drilling Program (ODP) Site 871 in the western Pacific warm pool, we estimate the tropical Pacific climate sensitivity parameter (λ) to be 0.94–1.06 °C (W m⁻²)⁻¹, higher than that predicted by model simulations of the Last Glacial Maximum or by models of doubled greenhouse gas concentration forcing. This result suggests that models may not yet adequately represent the long-term feedbacks related to ocean circulation, vegetation and associated dust, or the cryosphere, and/or may underestimate the effects of tropical clouds or other short-term feedback processes.”

Citation: Kelsey A. Dyez and A. Christina Ravelo, Geology, v. 41 no. 1 p. 23-26, doi: 10.1130/G33425.1.

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Dynamics played a major role for the Arctic ozone deficit in 2011

Attribution of the Arctic ozone column deficit in March 2011 – Isaksen et al. (2012)

Highlights: •Good model agreement with observations; •The model reproduces the Arctic ozone deficit in 2011; •Dynamics play a major role for the ozone deficit in 2011.

Abstract: “Arctic column ozone reached record low values (∼310 DU) during March of 2011, exposing Arctic ecosystems to enhanced UV-B. We identify the cause of this anomaly using the Oslo CTM2 atmospheric chemistry model driven by ECMWF meteorology to simulate Arctic ozone from 1998 through 2011. CTM2 successfully reproduces the variability in column ozone, from week to week, and from year to year, correctly identifying 2011 as an extreme anomaly over the period. By comparing parallel model simulations, one with all Arctic ozone chemistry turned off on January 1, we find that chemical ozone loss in 2011 is enhanced relative to previous years, but it accounted for only 23% of the anomaly. Weakened transport of ozone from middle latitudes, concurrent with an anomalously strong polar vortex, was the primary cause of the low ozone When the zonal winds relaxed in mid-March 2011, Arctic column ozone quickly recovered.”

Citation: Isaksen, I. S. A., et al. (2012), Attribution of the Arctic ozone column deficit in March 2011, Geophys. Res. Lett., 39, L24810, doi:10.1029/2012GL053876.

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Accelerated loss of alpine glaciers in the Kodar Mountains of SE Siberia

Accelerated loss of alpine glaciers in the Kodar Mountains, south-eastern Siberia – Stokes et al. (2012)

Highlights: ► First ever multi-year study of glacier change from the Kodar Mountains, SE Siberia ► Small decline in glacier area from the 1960s to 1995 followed by dramatic reduction ► Reduction coincides with a marked summer warming trend that began in the 1980s ► Topography and supra-glacial debris cover modulate glacier response ► These glaciers may transition into a type of rock glacier within a few decades.

Abstract: “The recession of mountain glaciers around the world has been linked to anthropogenic climate change and small glaciers (e.g. < 2 km²) are thought to be particularly vulnerable, with reports of their disappearance from several regions. However, the response of small glaciers to climate change can be modulated by non-climatic factors such as topography and debris cover and there remain a number of regions where their recent change has evaded scrutiny. This paper presents results of the first multi-year remote sensing survey of glaciers in the Kodar Mountains, the only glaciers in SE Siberia, which we compare to previous glacier inventories from this continental setting that reported total glacier areas of 18.8 km² in ca. 1963 (12.6 km² of exposed ice) and 15.5 km² in 1974 (12 km² of exposed ice). Mapping their debris-covered termini is difficult but delineation of debris-free ice on Landsat imagery reveals 34 glaciers with a total area of 11.72 ± 0.72 km² in 1995, followed by a reduction to 9.53 ± 0.29 km² in 2001 and 7.01 ± 0.23 km² in 2010. This represents a ~ 44% decrease in exposed glacier ice between ca. 1963 and 2010, but with 40% lost since 1995 and with individual glaciers losing as much as 93% of their exposed ice. Thus, although continental glaciers are generally thought to be less sensitive than their maritime counterparts, a recent acceleration in shrinkage of exposed ice has taken place and we note its coincidence with a strong summer warming trend in the region initiated at the start of the 1980s. Whilst smaller and shorter glaciers have, proportionally, tended to shrink more rapidly, we find no statistically significant relationship between shrinkage and elevation characteristics, aspect or solar radiation. This is probably due to the small sample size, limited elevation range, and topographic setting of the glaciers in deep valleys-heads. Furthermore, many of the glaciers possess debris-covered termini and it is likely that the ablation of buried ice is lagging the shrinkage of exposed ice, such that a growth in the proportion of debris cover is occurring, as observed elsewhere. If recent trends continue, we hypothesise that glaciers could evolve into a type of rock glacier within the next few decades, introducing additional complexity in their response and delaying their potential demise.”

Citation: Chris R. Stokes, Maria Shahgedanova, Ian S. Evans, Victor V. Popovnin, Global and Planetary Change, http://dx.doi.org/10.1016/j.gloplacha.2012.12.010.

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Central West Antarctica among the most rapidly warming regions on Earth

Central West Antarctica among the most rapidly warming regions on Earth – Bromwich et al. (2012)

Abstract: “There is clear evidence that the West Antarctic Ice Sheet is contributing to sea-level rise. In contrast, West Antarctic temperature changes in recent decades remain uncertain. West Antarctica has probably warmed since the 1950s, but there is disagreement regarding the magnitude, seasonality and spatial extent of this warming. This is primarily because long-term near-surface temperature observations are restricted to Byrd Station in central West Antarctica, a data set with substantial gaps. Here, we present a complete temperature record for Byrd Station, in which observations have been corrected, and gaps have been filled using global reanalysis data and spatial interpolation. The record reveals a linear increase in annual temperature between 1958 and 2010 by 2.4±1.2 °C, establishing central West Antarctica as one of the fastest-warming regions globally. We confirm previous reports of West Antarctic warming, in annual average and in austral spring and winter, but find substantially larger temperature increases. In contrast to previous studies, we report statistically significant warming during austral summer, particularly in December–January, the peak of the melting season. A continued rise in summer temperatures could lead to more frequent and extensive episodes of surface melting of the West Antarctic Ice Sheet. These results argue for a robust long-term meteorological observation network in the region.”

Citation: David H. Bromwich, Julien P. Nicolas, Andrew J. Monaghan, Matthew A. Lazzara, Linda M. Keller, George A. Weidner & Aaron B. Wilson, Nature Geoscience, 2012, doi:10.1038/ngeo1671.

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Other studies from last week

Rainfall variations in south-eastern Australia part 1: consolidating evidence from pre-instrumental documentary sources, 1788–1860 – Fenby & Gergis (2012)

Rainfall variations in south-eastern Australia part 2: a comparison of documentary, early instrumental and palaeoclimate records, 1788–2008 – Gergis & Ashcroft (2012)

Impact of anthropogenic absorbing aerosols on clouds and precipitation: A review of recent progresses – Wang (2012)

Impact of late Holocene climate variability and anthropogenic activities on Biscayne Bay (Florida, U.S.A.): Evidence from diatoms – Wachnicka et al. (2012)

Feedbacks in emission-driven and concentration-driven global carbon budgets – Boer & Arora (2012)

Changes in Arctic sea ice result in increasing light transmittance and absorption – Nicolaus et al. (2012)

A global analysis of soil microbial biomass carbon, nitrogen and phosphorus in terrestrial ecosystems – Xu et al. (2012)

Epifauna dynamics at an offshore foundation – implications of future wind power farming in the North Sea – Krone et al. (2012)

Effects of two decades of rising sea surface temperatures on sublittoral macrobenthos communities in Northern Ireland, UK – Goodwin et al. (2012)

Deconstructing the Hadley cell heat transport – Heaviside & Czaja (2012)

Temperature dependent climate projection deficiencies in CMIP5 models – Christensen & Boberg (2012)

Methane emissions from wetlands: biogeochemical, microbial, and modeling perspectives from local to global scales – Bridgham et al. (2012)

Coral record of reduced El Niño activity in the early 15th to middle 17th centuries – Hereid et al. (2012)

Zn isotope evidence for immediate resumption of primary productivity after snowball Earth – Kunzmann et al. (2012)

Improved estimates and understanding of global albedo and atmospheric solar absorption – Kim & Ramanathan (2012)

Detecting non-linear response of spring phenology to climate change by Bayesian analysis – Pope et al. (2012)

The uneven response of different snow measures to human-induced climate warming – Pierce & Cayan (2012)

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CLASSIC OF THE WEEK: Williamson (1769)

An Attempt to Account for the Change of Climate, Which Has Been Observed in the Middle Colonies in North-America – Williamson (1769) [FULL TEXT]

Abstract: No abstract. First paragraph: “It is generally remarked by people who have resided long in Pennsylvania and the neighbouring Colonies, that within the last forty or fifty years there has been a very observable Change of Climate, that our winters are not so intensely cold, nor our summers so disagreeably warm as they have been.”

Citation: Hugh Williamson, Transactions of the American Philosophical Society, Vol. 1, (Jan. 1, 1769 – Jan. 1, 1771) (pp. 272-280).

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About this series. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. Here’s the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.