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Archive for April, 2011

Baby mammoth ate the evidence of its environment

Posted by Ari Jokimäki on April 28, 2011

A frozen and mummified baby mammoth was found in 2007 from Yamal peninsula. The species of the baby mammoth was woolly mammoth (Mammuthus primigenius) and it was named as Lyuba. Luyba was about 1-1,5 months old when it died. According to radiocarbon dating, Lyuba died about 45,400 calendar years ago.

Luyba was fully intact otherwise but it didn’t have hair anymore. Lyuba is only the second baby mammoth which has been found with its intestinal tract. Baby mammoth found in 1977 and named as Dima had also intestinal tract, but it was partly destroyed. Lyuba’s intestinal tract was fully intact, which makes this finding very significant.

In a recently published study the contents of Lyuba’s intestinal tract were analysed. Based on the contents, researchers tried to determine in what kind of environment Lyuba lived. They made pollen, phytolith (mineral found from plant bodies), plant fossil, and mineral analysis on the intestinal contents. Based on these analyses, the environment where Lyuba lived was reconstructed.

Phytolith analysis showed, that there were mosses, grasses, sedges, and herbs in the intestinal tract. There were also some evidence of dry environment and acid soil conditions. Pollen analysis showed mostly tree and shrub species of which most abundant were conifers from pine family (Pinaceae) and two birch species (Betula pubescens and Betula nana). The pollen of most of these species travels far, so it is difficult to determine local environment based on them. Pollen of Betula nana (dwarf birch) doesn’t travel that far so it is indicative of local environment. There are lot of modern species of the region present in the pollen. Luyba lived in a region which was covered by grasses and sedges. There were also other herbaceous plants living in the area here and there and also dwarf birch.

In Lyuba’s intestinal tract there were some mosses which also live in modern arctic tundra and boreal forest. There were some seeds from such sedges and herbacoeus plants that also are arctic tundra and boreal forest species. Among found plants were species from both wet and dry environments. There were also some animal remains in the intestinal tract, including Daphnia species, worm remains, parts from insects and spiders, and one small mammal bone (Microtus sp.). Luyba was too young to eat plants, so it is probable (and there were some evidence found suggesting this) that Lyuba got the found species to its intestinal tract by eating the feces of adult mammoths. Modern baby elephants do that also.

Reference: Pavel A. Kosintsev, Elena G. Lapteva, Svetlana S. Trofimova, Oksana G. Zanina, Aleksey N. Tikhonov and Johannes Van der Plicht, Environmental Reconstruction Inferred From The Intestinal Contents Of The Yamal Baby Mammoth Lyuba (Mammuthus Primigenius Blumenbach, 1799), Quaternary International, 2011, doi:10.1016/j.quaint.2011.03.027. [abstract]


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Cosmic ray contribution to global warming negligible

Posted by Ari Jokimäki on April 26, 2011

There has been claims that cosmic rays could have contributed significantly to global warming. According to a new study that is not the case. Instead, during the last 50 years, cosmic rays seemed to have caused warming of about 0.002°C – a negligible amount compared to observed warming.

Cosmic rays have been claimed to be a significant source for the formation of cloud condensation nuclei and through that they have been claimed to affect Earth’s climate significantly. There has been many studies debunking these claims and currently it seems that the possible effect of cosmic rays on the climate is small. It is however likely that there are some mechanisms by which cosmic rays do affect cloud formation at least a little. For example, recently a correlation was found in Europe between diurnal temperature range (difference between daily maximum and minimum temperatures) and strong cosmic ray flux changes (Forbush decreases and ground level enhancements).

A new study by Erlykin et al. evaluates the effects of cosmic rays to cloud cover. The paper discusses previous cosmic ray research, and performs some new analysis. They use cloud cover measurements of International Satellite Cloud Climatology Project (ISCCP). There has been criticisms of ISCCP data, but the researchers believe that ISCCP problems do not affect their results.

Evidence of cosmic ray effects

Solar activity changes during the sunspot cycle and that affects Earth’s temperature. According to Erlykin et al. the change in temperature then affects the height of low clouds. The change of height makes some of the low clouds migrate to medium cloud region. This would then cause a decrease in low cloud amount. This would also be a candidate for the origin of the correlation between cosmic ray flux and low cloud cover (because solar activity changes are known to affect also cosmic ray flux). When analysing cloud cover changes it would make sense to look at the changes in both the low and medium clouds. When both low and medium clouds are included to the correlation analysis, the correlation with cosmic ray flux is poor.

Forbush decreases (few percent decrease in cosmic ray flux that lasts few days) have been claimed to cause cloud cover changes. However, the observed correlations between cloud cover changes and cosmic ray flux during a few Forbush decreases could have been coincidental. Additionally, delay between the changes in cosmic ray flux and in cloud cover seems to have been too long for a physical cause. Some of the strongest Forbush decreases have also been associated with strong changes in solar activity, which also places more clouds over the cosmic ray hypothesis.

Nevertheless there are some evidence relating to Forbush decreases that suggests some kind of effect in cloud cover. The strongest effect seems to lie in the stratosphere, but there is also some evidence for an effect in troposphere. It is unclear if these effects are due to cosmic rays or solar activity.

For cosmic ray flux ground level enhancements there also is some evidence of cloud effects. The strongest effect seems to occur in the poles which might suggest genuine cosmic ray involvement. Erlykin et al. estimate a global effect of about 1 % to cloud cover during ground level enhancements.

In a recent analysis it was found out that in mid-latitudes rapid changes in cloud cover are associated with changes in cosmic ray flux and in surface temperature. Strong reaction here only occurs during the rapid cloud cover changes which are rare events, so the total effect of cosmic rays still seems to be small. Here too it is unclear if the observed effects are due to cosmic rays or simultaneous changes in solar activity.

In the case of these rapid changes, the rate of change in clouds and in cosmic rays have been different which speaks against the cosmic ray origin. On the other hand, linking these cloud changes to solar activity is also problematic, because most of the UV radiation stops in the stratosphere and therefore would not be able to cause changes to most of the cloud cover. It is possible that the explanation for cloud changes is found in surface temperature changes caused by solar activity changes.

There is lot of evidence from polar regions on stratospheric cosmic ray effects, which usually are related to solar flares. It seems that cosmic rays have an effect on stratospheric aerosols, ozone, wind, temperature, pressure and ionisation. There are also some evidence of possible effect on stratospheric clouds during Forbush decreases and other cosmic ray flux changes, but the size of the possible effect is unclear.

Correlation between cosmic ray flux and cloud cover

Analysis of cloud cover correlation between cosmic rays and UV radiation reveals that correlation is significant only in these cases: low cloud cover with cosmic rays (positive correlation) and with UV radiation (negative), medium cloud cover with UV radiation (positive), and high cloud cover with cosmic rays (negative). For the case of UV radiation, the different sign for the correlation with low and medium cloud cover might be explainable by part of low cloud cover changing to medium cloud cover when surface temperature changes. For cosmic rays, the negative correlation with high cloud cover is not what would be expected from ionization mechanism.

The correlation of cosmic rays with low cloud cover is the correlation that has been claimed to cause the global warming. However, the spatial distribution of the correlation does not fit to the expectations from cosmic ray origin. Correlation is strong in mid-latitudes, but weak in the poles and in the equator. Mid-latitude correlation is about 8 times higher than the correlation in equator and in poles. This distribution of correlation results a possible effect to global cloud cover which is smaller than 1%.

According to Erlykin et al. the cosmic ray flux has decreased about 0.6% in last 50 years. Assuming 1% effect of the cosmic rays to cloud cover, this would cause a change of 0.002°C in global surface temperature. This is negligible compared to the observed global warming in last 50 years. In conclusion, while cosmic rays do seem to have some minor effects to different things in the atmosphere, they do not seem to have anything to do with global warming.

Source: A.D. Erlykin, B.A. Laken and A.W. Wolfendale, Cosmic ray effects on cloud cover and their relevance to climate change, Journal of Atmospheric and Solar-Terrestrial Physics, doi:10.1016/j.jastp.2011.03.001. [abstract]

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New research from last week 16/2011

Posted by Ari Jokimäki on April 25, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news. Planet 3.0 also reports new research.

Published last week:

Global river flow has decreased

The impact of climate, CO2, nitrogen deposition and land use change on simulated contemporary global river flow – Shi et al. (2011) “We investigated how climate, rising atmospheric CO2 concentration, increasing anthropogenic nitrogen deposition and land use change influenced continental river flow over the period 1948–2004 using the Community Land Model version 4 (CLM4) with coupled river transfer model (RTM), a global river routing scheme. The model results indicate that the global mean river flow shows significant decreasing trend and climate forcing likely functions as the dominant controller of the downward trend during the study period. Nitrogen deposition and land use change account for about 5% and 2.5% of the decrease in simulated global scale river flow, respectively, while atmospheric CO2 accounts for an upward trend. However, the relative role of each driving factor is heterogeneous across regions in our simulations. The trend in river flow for the Amazon River basin is primarily explained by CO2, while land use change accounts for 27.4% of the downward trend in river flow for the Yangtze rive basin. Our simulations suggest that to better understand the trends of river flow, it is not only necessary to take into account the climate, but also to consider atmospheric composition, carbon-nitrogen interaction and land use change, particularly for regional scales.” Shi, X., J. Mao, P. E. Thornton, F. M. Hoffman, and W. M. Post (2011), Geophys. Res. Lett., 38, L08704, doi:10.1029/2011GL046773.

Changes in lake area in Alaska

Mechanisms influencing changes in lake area in Alaskan boreal forest – Roach et al. (2011) “During the past ∼50 years, the number and area of lakes have declined in several regions in boreal forests. However, there has been substantial finer-scale heterogeneity; some lakes decreased in area, some showed no trend, and others increased. The objective of this study was to identify the primary mechanisms underlying heterogeneous trends in closed-basin lake area. Eight lake characteristics (δ18O, electrical conductivity, surface:volume index, bank slope, floating mat width, peat depth, thaw depth at shoreline, and thaw depth at the forest boundary) were compared for 15 lake pairs in Alaskan boreal forest where one lake had decreased in area since ∼1950, and the other had not. Mean differences in characteristics between paired lakes were used to identify the most likely of nine mechanistic scenarios that combined three potential mechanisms for decreasing lake area (talik drainage, surface water evaporation, and terrestrialization) with three potential mechanisms for non-decreasing lake area (sub-permafrost groundwater recharge through an open talik, stable permafrost, and thermokarst). A priori expectations of the direction of mean differences between decreasing and non-decreasing paired lakes were generated for each scenario. Decreasing lakes had significantly greater electrical conductivity, greater surface:volume indices, shallower bank slopes, wider floating mats, greater peat depths, and shallower thaw depths at the forest boundary. These results indicated that the most likely scenario was terrestrialization as the mechanism for lake area reduction combined with thermokarst as the mechanism for non-decreasing lake area. Terrestrialization and thermokarst may have been enhanced by recent warming which has both accelerated permafrost thawing and lengthened the growing season, thereby increasing plant growth, floating mat encroachment, transpiration rates, and the accumulation of organic matter in lake basins. The transition to peatlands associated with terrestrialization may provide a transient increase in carbon storage enhancing the role of northern ecosystems as major stores of global carbon.” Jennifer Roach, Brad Griffith, Dave Verbyla, Jeremy Jones, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02446.x.

Hirantian glaciation in Iran Zagros Mountains

Stratigraphic evidence for the Hirnantian (latest Ordovician) glaciation in the Zagros Mountains, Iran – Ghavidel-syooki et al. (2011) “High-latitude Hirnantian diamictites (Dargaz Formation) and lower–Silurian kerogenous black shales (Sarchahan Formation) are locally exposed in the Zagros Mountains. The glaciogenic Dargaz deposits consist of three progradational/retrogradational cycles, each potentially controlled by the regional advance and retreat of the Hirnantian ice sheet. Glacial incisions of sandstone packages change laterally from simple planar to high-relief (< 40 m deep) scalloped truncating surfaces that join laterally forming complex polyphase unconformities that scour into the underlying Seyahou Formation. The glaciated source area was to the present-day west, in the region of the Arabian Shield, where numerous tunnel valleys have been reported. Based on a study of palynomorphs and graptolites, the glaciomarine Dargaz diamictites are dated as Hirnantian, whereas the youngest Sarchahan black shales are diachronous throughout the Zagros, ranging from the Hirnantian persculptus to the earliest Aeronian (Llandovery) triangulatus zones. The diachronism is related to onlapping geometries capping an inherited glaciogenic palaeorelief that preserved different depth incisions and source areas. Our data suggest the presence of Hirnantian satellite ice caps adjacent the Zagros margin of Arabia and allow us to fill a gap in the present knowledge of the peripheral extension of the Late Ordovician ice sheet." Mohammad Ghavidel-syooki, J. Javier Álvaro, Leonid Popov, Mansoureh Ghobadi Pour, Mohammad H. Ehsani and Anna Suyarkova, Palaeogeography, Palaeoclimatology, Palaeoecology, doi:10.1016/j.palaeo.2011.04.011.

Climate variability during last 800kyr

Interglacial and glacial variability from the last 800 ka in marine, ice and terrestrial archives – Lang & Wolff (2011) “We have compiled 37 ice, marine and terrestrial palaeoclimate records covering the last 800 000 years in order to assess the pattern of glacial and interglacial strength, and termination amplitude. Records were selected based on their length, completeness and resolution, and their age models were updated, where required, by alignment to the LR04 benthic δ18O stack. The resulting compilation allows comparison of individual glacial to interglacial transitions with confidence, but the level of synchronisation is inadequate for discussion of temporal phasing. The comparison of interglacials and glacials concentrates on the peaks immediately before and after terminations; particularly strong and weak glacials and interglacials have been identified. This confirms that strong interglacials are confined to the last 450 ka, and that this is a globally robust pattern; however weak interglacials (i.e. marine isotope stage 7) can still occur in this later period. Strong glacial periods are also concentrated in the recent half of the records, although marine isotope stage 16 is strong in many δ18O records. Strong interglacials, particularly in the marine isotopic records, tend to follow strong glacials, suggesting that we should not expect interglacial strength to be strongly influenced by the instantaneous astronomical forcing. Many interglacials have a complex structure, with multiple peaks and troughs whose origin needs to be understood. However this compilation emphasises the under-representation of terrestrial environments and highlights the need for long palaeoclimate records from these areas. The main result of this work is the compiled datasets and maps of interglacial strength which provide a target for modelling studies and for conceptual understanding.” Lang, N. and Wolff, E. W., Clim. Past, 7, 361-380, doi:10.5194/cp-7-361-2011, 2011. [full text]

Positive feedback from atmospheric methane chemistry

Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions – Isaksen et al. (2011) “The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art” atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming.” Isaksen, I. S. A., M. Gauss, G. Myhre, K. M. Walter Anthony, and C. Ruppel (2011), Global Biogeochem. Cycles, 25, GB2002, doi:10.1029/2010GB003845.

Black carbon layers in atmosphere

Free tropospheric black carbon aerosol measurements using high altitude balloon: Do BC layers build “their own homes” up in the atmosphere? – Babu et al. (2011) “First ever in-situ measurements of black carbon (BC) aerosols in the troposphere (up to 9 km) made over central India and the resulting atmospheric impact as revealed by the environment lapse rate are presented. The altitude distribution of BC showed multiple peaks; two surprisingly large peaks, one at ∼4.5 km, and another above 8 km. Associated with these, rapid decrease in the environmental lapse rate and a sharp increase in the atmosphere stability were observed, probably caused by the atmospheric warming by the BC layers. This important observation calls for extensive high altitude profiling of BC to quantify the resultant warming, increase in stability and consequent increase in BC lifetime.” Babu, S. S., K. K. Moorthy, R. K. Manchanda, P. R. Sinha, S. K. Satheesh, D. P. Vajja, S. Srinivasan, and V. H. A. Kumar (2011), Geophys. Res. Lett., 38, L08803, doi:10.1029/2011GL046654.

Himalayan glaciers – melting

Multi-decadal mass loss of glaciers in the Everest area (Nepal Himalaya) derived from stereo imagery – Bolch et al. (2011) “Mass loss of Himalayan glaciers has wide-ranging consequences such as changing runoff distribution, sea level rise and an increasing risk of glacial lake outburst floods (GLOFs). The assessment of the regional and global impact of glacier changes in the Himalaya is, however, hampered by a lack of mass balance data for most of the range. Multi-temporal digital terrain models (DTMs) allow glacier mass balance to be calculated. Here, we present a time series of mass changes for ten glaciers covering an area of about 50 km2 south and west of Mt. Everest, Nepal, using stereo Corona spy imagery (years 1962 and 1970), aerial images and recent high resolution satellite data (Cartosat-1). This is the longest time series of mass changes in the Himalaya. We reveal that the glaciers have been significantly losing mass since at least 1970, despite thick debris cover. The specific mass loss for 1970–2007 is 0.32 ± 0.08 m w.e. a−1, however, not higher than the global average. Comparisons of the recent DTMs with earlier time periods indicate an accelerated mass loss. This is, however, hardly statistically significant due to high uncertainty, especially of the lower resolution ASTER DTM. The characteristics of surface lowering can be explained by spatial variations of glacier velocity, the thickness of the debris-cover, and ice melt due to exposed ice cliffs and ponds.” Bolch, T., Pieczonka, T., and Benn, D. I., The Cryosphere, 5, 349-358, doi:10.5194/tc-5-349-2011, 2011. [full text]

Methane sources and sinks 2006-2008

Source attribution of the changes in atmospheric methane for 2006–2008 – Bousquet et al. (2011) “The recent increase of atmospheric methane is investigated by using two atmospheric inversions to quantify the distribution of sources and sinks for the 2006–2008 period, and a process-based model of methane emissions by natural wetland ecosystems. Methane emissions derived from the two inversions are consistent at a global scale: emissions are decreased in 2006 (−7 Tg) and increased in 2007 (+21 Tg) and 2008 (+18 Tg), as compared to the 1999–2006 period. The agreement on the latitudinal partition of the flux anomalies for the two inversions is fair in 2006, good in 2007, and not good in 2008. In 2007, a positive anomaly of tropical emissions is found to be the main contributor to the global emission anomalies (~60–80%) for both inversions, with a dominant share attributed to natural wetlands (~2/3), and a significant contribution from high latitudes (~25%). The wetland ecosystem model produces smaller and more balanced positive emission anomalies between the tropics and the high latitudes for 2006, 2007 and 2008, mainly due to precipitation changes during these years. At a global scale, the agreement between the ecosystem model and the inversions is good in 2008 but not satisfying in 2006 and 2007. Tropical South America and Boreal Eurasia appear to be major contributors to variations in methane emissions consistently in the inversions and the ecosystem model. Finally, changes in OH radicals during 2006–2008 are found to be less than 1% in inversions, with only a small impact on the inferred methane emissions.” Bousquet, P., Ringeval, B., Pison, I., Dlugokencky, E. J., Brunke, E.-G., Carouge, C., Chevallier, F., Fortems-Cheiney, A., Frankenberg, C., Hauglustaine, D. A., Krummel, P. B., Langenfelds, R. L., Ramonet, M., Schmidt, M., Steele, L. P., Szopa, S., Yver, C., Viovy, N., and Ciais, P., Atmos. Chem. Phys., 11, 3689-3700, doi:10.5194/acp-11-3689-2011, 2011. [full text]

Greenland melted rapidly also between 1920-1960

A reconstruction of annual Greenland ice melt extent, 1784–2009 – Frauenfeld et al. (2011) “The total extent of ice melt on the Greenland ice sheet has been increasing during the last three decades. The melt extent observed in 2007 in particular was the greatest on record according to several satellite-derived records of total Greenland melt extent. Total annual observed melt extent across the Greenland ice sheet has been shown to be strongly related to summer temperature measurements from stations located along Greenland’s coast, as well as to variations in atmospheric circulation across the North Atlantic. We make use of these relationships along with historical temperature and circulation observations to develop a near-continuous 226 year reconstructed history of annual Greenland melt extent dating from 2009 back into the late eighteenth century. We find that the recent period of high-melt extent is similar in magnitude but, thus far, shorter in duration, than a period of high melt lasting from the early 1920s through the early 1960s. The greatest melt extent over the last 2 1/4 centuries occurred in 2007; however, this value is not statistically significantly different from the reconstructed melt extent during 20 other melt seasons, primarily during 1923–1961.” Frauenfeld, O. W., P. C. Knappenberger, and P. J. Michaels (2011), A reconstruction of annual Greenland ice melt extent, 1784–2009, J. Geophys. Res., 116, D08104, doi:10.1029/2010JD014918.

See also Jason Box’s comments on this paper.

Small climatic effect of methane release from hydrates in next 100 years

Rising Arctic Ocean temperatures cause gas hydrate destabilization and ocean acidification – Biastoch et al. (2011) “Vast amounts of methane hydrates are potentially stored in sediments along the continental margins, owing their stability to low temperature – high pressure conditions. Global warming could destabilize these hydrates and cause a release of methane (CH4) into the water column and possibly the atmosphere. Since the Arctic has and will be warmed considerably, Arctic bottom water temperatures and their future evolution projected by a climate model were analyzed. The resulting warming is spatially inhomogeneous, with the strongest impact on shallow regions affected by Atlantic inflow. Within the next 100 years, the warming affects 25% of shallow and mid-depth regions containing methane hydrates. Release of methane from melting hydrates in these areas could enhance ocean acidification and oxygen depletion in the water column. The impact of methane release on global warming, however, would not be significant within the considered time span.” Biastoch, A., et al. (2011), Geophys. Res. Lett., 38, L08602, doi:10.1029/2011GL047222..

Permafrost melting threatens Siberian ecosystems

Dynamics of the larch taiga–permafrost coupled system in Siberia under climate change – Zhang et al. (2011) “Larch taiga, also known as Siberian boreal forest, plays an important role in global and regional water–energy–carbon (WEC) cycles and in the climate system. Recent in situ observations have suggested that larch-dominated taiga and permafrost behave as a coupled eco-climate system across a broad boreal zone of Siberia. However, neither field-based observations nor modeling experiments have clarified the synthesized dynamics of this system. Here, using a new dynamic vegetation model coupled with a permafrost model, we reveal the processes of interaction between the taiga and permafrost. The model demonstrates that under the present climate conditions in eastern Siberia, larch trees maintain permafrost by controlling the seasonal thawing of permafrost, which in turn maintains the taiga by providing sufficient water to the larch trees. The experiment without permafrost processes showed that larch would decrease in biomass and be replaced by a dominance of pine and other species that suffer drier hydroclimatic conditions. In the coupled system, fire not only plays a destructive role in the forest, but also, in some cases, preserves larch domination in forests. Climate warming sensitivity experiments show that this coupled system cannot be maintained under warming of about 2 °C or more. Under such conditions, a forest with typical boreal tree species (dark conifer and deciduous species) would become dominant, decoupled from the permafrost processes. This study thus suggests that future global warming could drastically alter the larch-dominated taiga–permafrost coupled system in Siberia, with associated changes of WEC processes and feedback to climate.” Ningning Zhang, Tetsuzo Yasunari and Takeshi Ohta, 2011 Environ. Res. Lett. 6 024003 doi: 10.1088/1748-9326/6/2/024003.

Ecosystem in the surface of glaciers

Alpine debris-covered glaciers as a habitat for plant life – Caccianiga et al. (2011) “Debris-covered glaciers represent a significant, increasing fraction of glaciers and can host plant life on their surface. The goal of this work was to evaluate the suitability of supraglacial debris as a habitat for plant life and to discuss its ecological and biogeographic role. The research was carried out on the Miage Glacier (Mont Blanc massif, Western Alps, Italy). Vegetation cover was sampled using a regular sampling grid, recording plant species and number of individuals in 71 plots. Detailed glaciological parameters (surface temperature, debris thickness, glacier surface velocity) were recorded or derived from published data. Relationships between vegetation and environmental variables were assessed through Generalized Linear Models, Principal Components Analysis and Canonical Correspondence Analysis. The glacier surface hosted a high biodiversity, with 40 vascular plant species, including trees and shrubs. Plant cover was arranged along an altitude/glacier velocity gradient, whilst debris thickness as low as 10 cm could sustain plant growth on moving ice. Glacier velocity was the main physical factor affecting vegetation cover, probably through its influence on debris stability. The observed species assemblage is comparable with those of subalpine glacier forelands, but with the addition of high-altitude species. Debris-covered glaciers can provide a relatively favourable habitat for plant life wherever the glacier surface is sufficiently stable, acting as a refugium of high-altitude taxa below their altitudinal limits. Glaciers may behave as a dispersal vector for alpine plant species, which could have been important both during glacial periods and during warm stages of the Holocene.” Marco Caccianiga, Carlo Andreis, Guglielmina Diolaiuti, Carlo D’Agata, Claudia Mihalcea, Claudio Smiraglia, The Holocene April 18, 2011, 0959683611400219, doi: 10.1177/0959683611400219.

Hockey stick from water temperature in Norway

A 2000 year record of Atlantic Water temperature variability from the Malangen Fjord, northeastern North Atlantic – Hald et al. (2011) “A high-resolution sedimentary record from the subarctic Malangen fjord in northern Norway, northeastern North Atlantic has been investigated in order to reconstruct variations in influx of Atlantic Water for the last 2000 years. The fjord provides a regional oceanographic climatic signal reflecting changes in the North Atlantic heat flux at this latitude because of its deep sill and the relatively narrow adjoining continental shelf. The reconstructions are based on oxygen and carbon isotopic studies of benthic foraminifera from a high accumulation basin in the Malangen fjord, providing subdecadal time resolution. A comparison between instrumental measurements of bottom water temperatures at the core location and the reconstructed temperatures from benthic foraminiferal δ18O for the same time period demonstrates that the stable isotope values reflect the bottom water temperatures very well. The reconstructed temperature record shows an overall decline in temperature of c. 1°C from c. 40 BC to AD 1350. This cooling trend is assumed to be driven by an orbital forced reduction in insolation. Superimposed on the general cooling trend are several periods of warmer or colder temperatures. The long-term fluctuations in the Malangen fjord are concurrent with fluctuations of Atlantic Water in the northern North Atlantic. Although they are not directly comparable, comparisons of atmospheric temperatures and marine records, indicate a close coupling between the climate systems. After AD 1800 the record shows an unprecedented warming within the last 2000 years.” M. Hald, G. R. Salomonsen, K. Husum, L. J. Wilson, The Holocene April 18, 2011, 0959683611400457, doi: 10.1177/0959683611400457.

AMO’s role significant in Northern Hemisphere’s climate

Atlantic Multidecadal Oscillation and Northern Hemisphere’s climate variability – Wyatt et al. (2011) “Proxy and instrumental records reflect a quasi-cyclic 50–80-year climate signal across the Northern Hemisphere, with particular presence in the North Atlantic. Modeling studies rationalize this variability in terms of intrinsic dynamics of the Atlantic Meridional Overturning Circulation influencing distribution of sea-surface-temperature anomalies in the Atlantic Ocean; hence the name Atlantic Multidecadal Oscillation (AMO). By analyzing a lagged covariance structure of a network of climate indices, this study details the AMO-signal propagation throughout the Northern Hemisphere via a sequence of atmospheric and lagged oceanic teleconnections, which the authors term the “stadium wave”. Initial changes in the North Atlantic temperature anomaly associated with AMO culminate in an oppositely signed hemispheric signal about 30 years later. Furthermore, shorter-term, interannual-to-interdecadal climate variability alters character according to polarity of the stadium-wave-induced prevailing hemispheric climate regime. Ongoing research suggests mutual interaction between shorter-term variability and the stadium wave, with indication of ensuing modifications of multidecadal variability within the Atlantic sector. Results presented here support the hypothesis that AMO plays a significant role in hemispheric and, by inference, global climate variability, with implications for climate-change attribution and prediction.” Marcia Glaze Wyatt, Sergey Kravtsov and Anastasios A. Tsonis, Climate Dynamics, DOI: 10.1007/s00382-011-1071-8.

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New research from last week 15/2011

Posted by Ari Jokimäki on April 18, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news. Planet 3.0 also reports new research.

Published last week:

Forests stabilize temperature

Extreme temperature analysis under forest cover compared to an open field – Ferrez et al. (2011) “We analyse air temperature data from 14 sites in Switzerland, each with two weather stations in close proximity, one under a forest canopy and the other in the open. We use the statistics of extremes to investigate how extremely high maximum and extremely low minimum temperatures depend on the effect of forest cover. Our analysis shows that temperature maxima at two nearby stations are less dependent than are temperature minima. Maxima under the canopy are influenced by altitude: for higher sites, the maxima are less variable and depend less on the open-field data. Southerly orientations increase the dependence of minimum temperatures and so reduce the sheltering effect during cold periods. Extreme maximum and minimum temperatures occur less within conifer forests, indicating that the insulation provided by conifers all over the year is more efficient than that provided by deciduous species. Steepness of slopes has a complex impact on distributions of extremes and on their dependence.” J. Ferrez, A.C. Davison and M. Rebetez, Agricultural and Forest Meteorology, doi:10.1016/j.agrformet.2011.03.005.

Downward IR decreasing due to clouds in one measurement site

Long-Term Trends in Downwelling Spectral Infrared Radiance over the U.S. Southern Great Plains – Gero & Turner (2011) “A trend analysis was applied to a 14-year time series of downwelling spectral infrared radiance observations from the Atmospheric Emitted Radiance Interferometer (AERI) located at the Atmospheric Radiation Measurement (ARM) site in the U.S. Southern Great Plains. The highly accurate calibration of the AERI instrument, performed every 10 minutes, ensures that any statistically significant trend in the observed data over this time can be attributed to changes in the atmospheric properties and composition, and not to changes in the sensitivity or responsivity of the instrument. The measured infrared spectra, numbering over 800,000, were classified as clear-sky, thin cloud, and thick cloud scenes using a neural network method. The AERI data record demonstrates that the downwelling infrared radiance is decreasing over this 14-year time period in the winter, summer, and autumn seasons but is increasing in the spring; these trends are statistically significant and are primarily due to long-term change in the cloudiness above the site. The AERI data also show many statistically significant trends on annual, seasonal, and diurnal time scales, with different trend signatures identified in the separate scene classifications. Given the decadal time span of the dataset, effects from natural variability should be considered in drawing broader conclusions. Nevertheless, this data set has high value due to the ability to infer possible mechanisms for any trends from the observations themselves, and to test the performance of climate models.” P. Jonathan Gero, David D. Turner, Journal of Climate 2011, doi: 10.1175/2011JCLI4210.1.

Warming and acidification bad for shelled pteropod

Impact of ocean acidification and elevated temperatures on early juveniles of the polar shelled pteropod Limacina helicina: mortality, shell degradation, and shell growth – Lischka et al. (2011) “Due to their aragonitic shell, thecosome pteropods may be particularly vulnerable to ocean acidification driven by anthropogenic CO2 emissions. This applies specifically to species inhabiting Arctic surface waters that are projected to become temporarily and locally undersaturated with respect to aragonite as early as 2016. This study investigated the effects of rising partial pressure of CO2 (pCO2) and elevated temperature on pre-winter juveniles of the polar pteropod Limacina helicina. After a 29 day experiment in September/October 2009 at three different temperatures and under pCO2 scenarios projected for this century, mortality, shell degradation, shell diameter and shell increment were investigated. Temperature and pCO2 had a significant effect on mortality, but temperature was the overriding factor. Shell diameter, shell increment and shell degradation were significantly impacted by pCO2 but not by temperature. Mortality was 46% higher at 8 °C than at in situ temperature (3 °C), and 14% higher at 1100 μatm than at 230 μatm. Shell diameter and increment were reduced by 10 and 12% at 1100 μatm and 230 μatm, respectively, and shell degradation was 41% higher at elevated compared to ambient pCO2. We conclude that pre-winter juveniles will be negatively affected by both rising temperature and pCO2 which may result in a possible decline in abundance of the overwintering population, the basis for next year’s reproduction.” Lischka, S., Büdenbender, J., Boxhammer, T., and Riebesell, U., Biogeosciences, 8, 919-932, doi:10.5194/bg-8-919-2011, 2011. [Full text]

Complexity of black carbon climatic effects

Dependence of climate forcing and response on the altitude of black carbon aerosols – Ban-Weiss et al. (2011) “Black carbon aerosols absorb solar radiation and decrease planetary albedo, and thus can contribute to climate warming. In this paper, the dependence of equilibrium climate response on the altitude of black carbon is explored using an atmospheric general circulation model coupled to a mixed layer ocean model. The simulations model aerosol direct and semi-direct effects, but not indirect effects. Aerosol concentrations are prescribed and not interactive. It is shown that climate response of black carbon is highly dependent on the altitude of the aerosol. As the altitude of black carbon increases, surface temperatures decrease; black carbon near the surface causes surface warming, whereas black carbon near the tropopause and in the stratosphere causes surface cooling. This cooling occurs despite increasing planetary absorption of sunlight (i.e. decreasing planetary albedo). We find that the trend in surface air temperature response versus the altitude of black carbon is consistent with our calculations of radiative forcing after the troposphere, stratosphere, and land surface have undergone rapid adjustment, calculated as “regressed” radiative forcing. The variation in climate response from black carbon at different altitudes occurs largely from different fast climate responses; temperature dependent feedbacks are not statistically distinguishable. Impacts of black carbon at various altitudes on the hydrological cycle are also discussed; black carbon in the lowest atmospheric layer increases precipitation despite reductions in solar radiation reaching the surface, whereas black carbon at higher altitudes decreases precipitation.” George A. Ban-Weiss, Long Cao, G. Bala and Ken Caldeira, Climate Dynamics, DOI: 10.1007/s00382-011-1052-y.

Future climate does not treat Greece very well

An integrated assessment of climate change impacts for Greece in the near future – Giannakopoulos et al. (2011) “Climate changes in the Mediterranean region, related to a significant increase in temperature and changes in precipitation patterns, can potentially affect local economies. Agriculture and tourism are undoubtedly the most important economic sources for Greece and these may be more strongly affected by changing future climate conditions. Climate change and their various negative impacts on human life are also detected in their environment; hence this study deals with implications, caused by changing climate, in urban and forest areas. Potential changes for the mid-twenty-first century (2021–2050) are analysed using a high-resolution regional climate model. This paper presents relevant climatic indices, indicative for potential implications which may jeopardise vital economic/environmental sectors of the country. The results provide insights into particular regions of the Greek territory that may undergo substantial impacts due to climate change. It is concluded that the duration of dry days is expected to increase in most of the studied agricultural regions. Winter precipitation generally decreases, whereas an increase in autumn precipitation is projected in most areas. Changing climate conditions associated with increased minimum temperatures (approximately 1.3°C) and decreased winter precipitation by 15% on average suggest that the risk for forest fires is intensified in the future. In urban areas, unpleasantly high temperatures during day and night will increase the feeling of discomfort in the citizens, while flash floods events are expected to occur more frequently. Another impact of climate change in urban regions is the increasing energy demand for cooling in summer. Finally, it was found that continental tourist areas of the Greek mainland will more often face heatwave episodes. In coastal regions, increased temperatures especially at night in combination with high levels of relative humidity can lead to conditions that are nothing less than uncomfortable for foreigners and the local population. In general, projected changes associated with temperature have a higher degree of confidence than those associated with precipitation.” Christos Giannakopoulos, Effie Kostopoulou, Konstantinos V. Varotsos, Kostas Tziotziou and Achilleas Plitharas, Regional Environmental Change, DOI: 10.1007/s10113-011-0219-8. [Full text]

More evidence for upwelling intensification in oceans

Coastal cooling and increased productivity in the main upwelling zone off Peru since the mid-twentieth century – Gutiérrez et al. (2011) “We reconstructed a high-resolution, alkenone-based sea surface temperature (SST) record spanning the last ca. 150 years, from a sediment core retrieved within the main upwelling zone off Peru. A conspicuous SST decline is evidenced since the 1950s despite interdecadal SST variability. Instrumental SST data and reanalysis of ECMWF ERA 40 winds suggest that the recent coastal cooling corresponds mainly to an intensification of alongshore winds and associated increase of upwelling in spring. Consistently, both proxy and instrumental data evidence increased productivity in phase with the SST cooling. Our data expand on previous reports on recent SST cooling in other Eastern Boundary upwelling systems and support scenarios that relate coastal upwelling intensification to global warming. Yet, further investigations are needed to assess the role of different mechanisms and forcings (enhanced local winds vs. spin-up of the South Pacific High Pressure cell).” Gutiérrez, D., et al. (2011), Geophys. Res. Lett., 38, L07603, doi:10.1029/2010GL046324.

Human fingerprint shows also in short satellite records

Atmospheric Climate Change Detection by Radio Occultation Data Using a Fingerprinting Method – Lackner et al. (2011) “The detection of climate change signals in rather short satellite datasets is a challenging task in climate research and requires high quality data with good error characterization. Global Navigation Satellite System (GNSS) radio occultation (RO) provides a novel record of high quality measurements of atmospheric parameters of the upper troposphere-lower stratosphere (UTLS) region. Due to characteristics such as long-term stability, self-calibration, and a very good height-resolution, RO data are well suited to investigate atmospheric climate change. This study describes the signals of ENSO and the QBO in the data and investigates whether the data already show evidence of a forced climate change signal, using an optimal-fingerprint technique. RO refractivity, geopotential height, and temperature within two trend periods (1995–2010 intermittently and 2001–2010 continuously) are investigated. The data show that an emerging climate change signal consistent with the projections of three global climate models from the Coupled Model Intercomparison Project cycle 3 (CMPI3) archive is detected for geopotential height of pressure levels at a 90 % confidence level both for the intermittent and continuous period, for the latter so far in a broad 50°S to 50°N band only. Such UTLS geopotential height changes reflect an overall tropospheric warming. 90 % confidence is not achieved for the temperature record when only large-scale aspects of the pattern are resolved. When resolving smaller-scale aspects, RO temperature trends appear stronger than GCM projected trends, the difference stemming mainly from the tropical lower-stratosphere, allowing for climate change detection at a 95 % confidence level. Overall an emerging trend signal is thus detected in the RO climate record, which is expected to increase further in significance as the record grows over the coming years. Small natural changes during the period suggest that the detected change is mainly caused by anthropogenic influence on climate.” Bettina C. Lackner and Andrea K. Steiner and Gottfried Kirchengast, Journal of Climate 2011, doi: 10.1175/2011JCLI3966.1.

Antarctic surface temperature record 50 to 25 million years ago

A record of Antarctic surface temperature between 25 and 50 m.y. ago – Dallai & Burgess (2011) “We present the first Antarctic terrestrial record of climate variations through the Cenozoic, based on the hydrogen isotope composition of hydrothermally altered minerals of intrusive rocks. This new record provides an independent geochemical proxy for continental climatic conditions; whereas, most land surface temperature proxies are biological. The temperature record is consistent with the range predicted by global climate models and proxy records for glacial and pre-glacial conditions in the Ross Sea region of Antarctica. The combined stable isotope (O and H) and age (40Ar-39Ar) determinations of hydrous mineral from Cenozoic igneous plutons and dikes show that the protracted time scale of magmatic activity and extensive hydrothermal exchange with local meteoric waters has preserved a semiquantitative climate signal of intervals in which atmospheric temperatures significantly fluctuated. These data also reveal that glacial episodes comparable with current polar conditions occurred repeatedly prior to geographical and thermal isolation of the Antarctic continent.” Luigi Dallai and Ray Burgess, Geology, v. 39 no. 5 p. 423-426, doi: 10.1130/G31569.1.

West Antarctic winter warming originates from tropics

Winter warming in West Antarctica caused by central tropical Pacific warming – Ding et al. (2011) “The Pacific sector of Antarctica, including both the Antarctic Peninsula and continental West Antarctica, has experienced substantial warming in the past 30 years. An increase in the circumpolar westerlies, owing in part to the decline in stratospheric ozone concentrations since the late 1970s, may account for warming trends in the peninsula region in austral summer and autumn. The more widespread warming in continental West Antarctica (Ellsworth Land and Marie Byrd Land) occurs primarily in austral winter and spring, and remains unexplained. Here we use observations of Antarctic surface temperature and global sea surface temperature, and atmospheric circulation data to show that recent warming in continental West Antarctica is linked to sea surface temperature changes in the tropical Pacific. Over the past 30 years, anomalous sea surface temperatures in the central tropical Pacific have generated an atmospheric Rossby wave response that influences atmospheric circulation over the Amundsen Sea, causing increased advection of warm air to the Antarctic continent. General circulation model experiments show that the central tropical Pacific is a critical region for producing the observed high latitude response. We conclude that, by affecting the atmospheric circulation at high southern latitudes, increasing tropical sea surface temperatures may account for West Antarctic warming through most of the twentieth century.” Qinghua Ding, Eric J. Steig, David S. Battisti & Marcel Küttel, Nature Geoscience, 2011, DOI: doi:10.1038/ngeo1129.

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Papers on gas leakage from natural gas industry

Posted by Ari Jokimäki on April 13, 2011

This is a list of papers on gas leakage from natural gas industry. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.

UPDATE (January 8, 2018): Alvarez et al. (2018), Boothroyd et al. (2018), and Omara et al. (2018) added.
UPDATE (September 7, 2018): Dedikov et al. (1999) added.
UPDATE (January 23, 2014): Miller et al. (2013), Karion et al. (2013), Allen et al. (2013), Pétron et al. (2012), Alvarez et al. (2012) added.
UPDATE (February 5, 2012): Howarth et al. (2011), Cathles et al. (2012), and Howarth et al. (2012) added.

Assessment of methane emissions from the U.S. oil and gas supply chain – Alvarez et al. (2018) “Methane emissions from the U.S. oil and natural gas supply chain were estimated by using ground-based, facility-scale measurements and validated with aircraft observations in areas accounting for ~30% of U.S. gas production. When scaled up nationally, our facility-based estimate of 2015 supply chain emissions is 13 ± 2 teragrams per year, equivalent to 2.3% of gross U.S. gas production. This value is ~60% higher than the U.S. Environmental Protection Agency inventory estimate, likely because existing inventory methods miss emissions released during abnormal operating conditions. Methane emissions of this magnitude, per unit of natural gas consumed, produce radiative forcing over a 20-year time horizon comparable to the CO2 from natural gas combustion. Substantial emission reductions are feasible through rapid detection of the root causes of high emissions and deployment of less failure-prone systems.” Ramón A. Alvarez, Daniel Zavala-Araiza, David R. Lyon, David T. Allen, Zachary R. Barkley, Adam R. Brandt, Kenneth J. Davis, Scott C. Herndon, Daniel J. Jacob, Anna Karion, Eric A. Kort, Brian K. Lamb, Thomas Lauvaux, Joannes D. Maasakkers, Anthony J. Marchese, Mark Omara, Stephen W. Pacala, Jeff Peischl, Allen L. Robinson, Paul B. Shepson, Colm Sweeney, Amy Townsend-Small, Steven C. Wofsy, Steven P. Hamburg (2018). Science 13 Jul 2018: Vol. 361, Issue 6398, pp. 186-188. DOI: 10.1126/science.aar7204 [Full text]

Methane Emissions from Natural Gas Production Sites in the United States: Data Synthesis and National Estimate – Omara et al. (2018) “We used site-level methane (CH4) emissions data from over 1000 natural gas (NG) production sites in eight basins, including 92 new site-level CH4 measurements in the Uinta, northeastern Marcellus, and Denver-Julesburg basins, to investigate CH4 emissions characteristics and develop a new national CH4 emission estimate for the NG production sector. The distribution of site-level emissions is highly skewed, with the top 5% of sites accounting for 50% of cumulative emissions. High emitting sites are predominantly also high producing (>10 Mcfd). However, low NG production sites emit a larger fraction of their CH4 production. When combined with activity data, we predict that this creates substantial variability in the basin-level CH4 emissions which, as a fraction of basin-level CH4 production, range from 0.90% for the Appalachian and Greater Green River to >4.5% in the San Juan and San Joaquin. This suggests that much of the basin-level differences in production-normalized CH4 emissions reported by aircraft studies can be explained by differences in site size and distribution of site-level production rates. We estimate that NG production sites emit total CH4 emissions of 830 Mg/h (95% CI: 530–1200), 63% of which come from the sites producing <100 Mcfd that account for only 10% of total NG production. Our total CH4 emissions estimate is 2.3 times higher than the U.S. Environmental Protection Agency’s estimate and likely attributable to the disproportionate influence of high emitting sites." Mark Omara, Naomi Zimmerman, Melissa R. Sullivan, Xiang Li, Aja Ellis, Rebecca Cesa, R. Subramanian, Albert A. Presto, Allen L. Robinson (2018). Environ. Sci. Technol., 2018, 52 (21), pp 12915–12925. DOI: 10.1021/acs.est.8b03535. [Full text]

Assessing fugitive emissions of CH4 from high-pressure gas pipelines in the UK – Boothroyd et al. (2018) “Natural gas pipelines are an important source of fugitive methane emissions in lifecycle greenhouse gas assessments but limited monitoring has taken place of UK pipelines to quantify fugitive emissions. This study investigated methane emissions from the UK high-pressure pipeline system (National Transmission System – NTS) for natural gas pipelines. Mobile surveys of CH4 emissions were conducted across four areas in the UK, with routes bisecting high-pressure pipelines (with a maximum operating pressure of 85 bar) and separate control routes away from the pipelines. A manual survey of soil gas measurements was also conducted along one of the high-pressure pipelines using a tunable diode laser. For the pipeline routes, there were 26 peaks above 2.1 ppmv CH4 at 0.23 peaks/km, compared with 12 peaks at 0.11 peaks/km on control routes. Three distinct thermogenic emissions were identified on the basis of the isotopic signal from these elevated concentrations with a peak rate of 0.03 peaks/km. A further three thermogenic emissions on pipeline routes were associated with pipeline infrastructure. Methane fluxes from control routes were statistically significantly lower than the fluxes measured on pipeline routes, with an overall pipeline flux of 627 (241–1123 interquartile range) tonnes CH4/km/yr. Soil gas CH4 measurements indicated a total flux of 62.6 kt CH4/yr, which equates to 2.9% of total annual CH4 emissions in the UK. We recommend further monitoring of the UK natural gas pipeline network, with assessments of transmission and distribution stations, and distribution pipelines necessary.” Ian M. Boothroyd, Sam Almond, Fred Worrall, Rosemary K. Davies, Richard J.Davies (2018). Science of The Total Environment, Volumes 631–632, 1 August 2018, Pages 1638-1648. [Full text]

Anthropogenic emissions of methane in the United States – Miller et al. (2013) “This study quantitatively estimates the spatial distribution of anthropogenic methane sources in the United States by combining comprehensive atmospheric methane observations, extensive spatial datasets, and a high-resolution atmospheric transport model. Results show that current inventories from the US Environmental Protection Agency (EPA) and the Emissions Database for Global Atmospheric Research underestimate methane emissions nationally by a factor of ∼1.5 and ∼1.7, respectively. Our study indicates that emissions due to ruminants and manure are up to twice the magnitude of existing inventories. In addition, the discrepancy in methane source estimates is particularly pronounced in the south-central United States, where we find total emissions are ∼2.7 times greater than in most inventories and account for 24 ± 3% of national emissions. The spatial patterns of our emission fluxes and observed methane–propane correlations indicate that fossil fuel extraction and refining are major contributors (45 ± 13%) in the south-central United States. This result suggests that regional methane emissions due to fossil fuel extraction and processing could be 4.9 ± 2.6 times larger than in EDGAR, the most comprehensive global methane inventory. These results cast doubt on the US EPA’s recent decision to downscale its estimate of national natural gas emissions by 25–30%. Overall, we conclude that methane emissions associated with both the animal husbandry and fossil fuel industries have larger greenhouse gas impacts than indicated by existing inventories.” Scot M. Miller, Steven C. Wofsy, Anna M. Michalak, Eric A. Kort, Arlyn E. Andrews, Sebastien C. Biraud, Edward J. Dlugokencky, Janusz Eluszkiewicz, Marc L. Fischer, Greet Janssens-Maenhout, Ben R. Miller, John B. Miller, Stephen A. Montzka, Thomas Nehrkorn, and Colm Sweeney, PNAS, 2013, doi: 10.1073/pnas.1314392110. [Full text]

Methane emissions estimate from airborne measurements over a western United States natural gas field – Karion et al. (2013) “Methane (CH4) emissions from natural gas production are not well quantified and have the potential to offset the climate benefits of natural gas over other fossil fuels. We use atmospheric measurements in a mass balance approach to estimate CH4 emissions of 55 ± 15 × 103 kg h−1 from a natural gas and oil production field in Uintah County, Utah, on 1 day: 3 February 2012. This emission rate corresponds to 6.2%–11.7% (1σ) of average hourly natural gas production in Uintah County in the month of February. This study demonstrates the mass balance technique as a valuable tool for estimating emissions from oil and gas production regions and illustrates the need for further atmospheric measurements to determine the representativeness of our single-day estimate and to better assess inventories of CH4 emissions.” Anna Karion, Colm Sweeney, Gabrielle Pétron, Gregory Frost, R. Michael Hardesty, Jonathan Kofler, Ben R. Miller, Tim Newberger, Sonja Wolter, Robert Banta, Alan Brewer, Ed Dlugokencky, Patricia Lang, Stephen A. Montzka, Russell Schnell, Pieter Tans, Michael Trainer, Robert Zamora, Stephen Conley, Geophysical Research Letters, Volume 40, Issue 16, pages 4393–4397, 28 August 2013, DOI: 10.1002/grl.50811.

Measurements of methane emissions at natural gas production sites in the United States – Allen et al. (2013) “Engineering estimates of methane emissions from natural gas production have led to varied projections of national emissions. This work reports direct measurements of methane emissions at 190 onshore natural gas sites in the United States (150 production sites, 27 well completion flowbacks, 9 well unloadings, and 4 workovers). For well completion flowbacks, which clear fractured wells of liquid to allow gas production, methane emissions ranged from 0.01 Mg to 17 Mg (mean = 1.7 Mg; 95% confidence bounds of 0.67–3.3 Mg), compared with an average of 81 Mg per event in the 2011 EPA national emission inventory from April 2013. Emission factors for pneumatic pumps and controllers as well as equipment leaks were both comparable to and higher than estimates in the national inventory. Overall, if emission factors from this work for completion flowbacks, equipment leaks, and pneumatic pumps and controllers are assumed to be representative of national populations and are used to estimate national emissions, total annual emissions from these source categories are calculated to be 957 Gg of methane (with sampling and measurement uncertainties estimated at ±200 Gg). The estimate for comparable source categories in the EPA national inventory is ∼1,200 Gg. Additional measurements of unloadings and workovers are needed to produce national emission estimates for these source categories. The 957 Gg in emissions for completion flowbacks, pneumatics, and equipment leaks, coupled with EPA national inventory estimates for other categories, leads to an estimated 2,300 Gg of methane emissions from natural gas production (0.42% of gross gas production).” David T. Allen, Vincent M. Torres, James Thomas, David W. Sullivan, Matthew Harrison, Al Hendler, Scott C. Herndon, Charles E. Kolb, Matthew P. Fraser, A. Daniel Hill, Brian K. Lamb, Jennifer Miskimins, Robert F. Sawyer, and John H. Seinfeld, PNAS, 2013, vol. 110 no. 44, 17768–17773, doi: 10.1073/pnas.1304880110. [Full text]

Greater focus needed on methane leakage from natural gas infrastructure – Alvarez et al. (2012) “Natural gas is seen by many as the future of American energy: a fuel that can provide energy independence and reduce greenhouse gas emissions in the process. However, there has also been confusion about the climate implications of increased use of natural gas for electric power and transportation. We propose and illustrate the use of technology warming potentials as a robust and transparent way to compare the cumulative radiative forcing created by alternative technologies fueled by natural gas and oil or coal by using the best available estimates of greenhouse gas emissions from each fuel cycle (i.e., production, transportation and use). We find that a shift to compressed natural gas vehicles from gasoline or diesel vehicles leads to greater radiative forcing of the climate for 80 or 280 yr, respectively, before beginning to produce benefits. Compressed natural gas vehicles could produce climate benefits on all time frames if the well-to-wheels CH4 leakage were capped at a level 45–70% below current estimates. By contrast, using natural gas instead of coal for electric power plants can reduce radiative forcing immediately, and reducing CH4 losses from the production and transportation of natural gas would produce even greater benefits. There is a need for the natural gas industry and science community to help obtain better emissions data and for increased efforts to reduce methane leakage in order to minimize the climate footprint of natural gas.” Ramón A. Alvarez, Stephen W. Pacala, James J. Winebrake, William L. Chameides, and Steven P. Hamburg, PNAS, 2013, vol. 109 no. 17, 6435–6440, doi: 10.1073/pnas.1202407109. [Full text]

Hydrocarbon emissions characterization in the Colorado Front Range: A pilot study – Pétron et al. (2012) “The multispecies analysis of daily air samples collected at the NOAA Boulder Atmospheric Observatory (BAO) in Weld County in northeastern Colorado since 2007 shows highly correlated alkane enhancements caused by a regionally distributed mix of sources in the Denver-Julesburg Basin. To further characterize the emissions of methane and non-methane hydrocarbons (propane, n-butane, i-pentane, n-pentane and benzene) around BAO, a pilot study involving automobile-based surveys was carried out during the summer of 2008. A mix of venting emissions (leaks) of raw natural gas and flashing emissions from condensate storage tanks can explain the alkane ratios we observe in air masses impacted by oil and gas operations in northeastern Colorado. Using the WRAP Phase III inventory of total volatile organic compound (VOC) emissions from oil and gas exploration, production and processing, together with flashing and venting emission speciation profiles provided by State agencies or the oil and gas industry, we derive a range of bottom-up speciated emissions for Weld County in 2008. We use the observed ambient molar ratios and flashing and venting emissions data to calculate top-down scenarios for the amount of natural gas leaked to the atmosphere and the associated methane and non-methane emissions. Our analysis suggests that the emissions of the species we measured are most likely underestimated in current inventories and that the uncertainties attached to these estimates can be as high as a factor of two.” Gabrielle Pétron, Gregory Frost, Benjamin R. Miller, Adam I. Hirsch, Stephen A. Montzka, Anna Karion, Michael Trainer, Colm Sweeney, Arlyn E. Andrews, Lloyd Miller, Jonathan Kofler, Amnon Bar-Ilan, Ed J. Dlugokencky, Laura Patrick, Charles T. Moore Jr., Thomas B. Ryerson, Carolina Siso, William Kolodzey, Patricia M. Lang, Thomas Conway, Paul Novelli, Kenneth Masarie, Bradley Hall, Douglas Guenther, Duane Kitzis, John Miller, David Welsh, Dan Wolfe, William Neff, Pieter Tans, Journal of Geophysical Research: Atmospheres (1984–2012), Volume 117, Issue D4, 27 February 2012, DOI: 10.1029/2011JD016360. [Full text]

Venting and leaking of methane from shale gas development: response to Cathles et al. – Howarth et al. (2012) “In April 2011, we published the first comprehensive analysis of greenhouse gas (GHG) emissions from shale gas obtained by hydraulic fracturing, with a focus on methane emissions. Our analysis was challenged by Cathles et al. (2012). Here, we respond to those criticisms. We stand by our approach and findings. The latest EPA estimate for methane emissions from shale gas falls within the range of our estimates but not those of Cathles et al. which are substantially lower. Cathles et al. believe the focus should be just on electricity generation, and the global warming potential of methane should be considered only on a 100-year time scale. Our analysis covered both electricity (30% of US usage) and heat generation (the largest usage), and we evaluated both 20- and 100-year integrated time frames for methane. Both time frames are important, but the decadal scale is critical, given the urgent need to avoid climate-system tipping points. Using all available information and the latest climate science, we conclude that for most uses, the GHG footprint of shale gas is greater than that of other fossil fuels on time scales of up to 100 years. When used to generate electricity, the shale-gas footprint is still significantly greater than that of coal at decadal time scales but is less at the century scale. We reiterate our conclusion from our April 2011 paper that shale gas is not a suitable bridge fuel for the 21st Century.” Robert W. Howarth, Renee Santoro and Anthony Ingraffea, Climatic Change, DOI: 10.1007/s10584-012-0401-0. [Full text]

A commentary on “The greenhouse-gas footprint of natural gas in shale formations” by R.W. Howarth, R. Santoro, and Anthony Ingraffea – Cathles et al. (2012) “Natural gas is widely considered to be an environmentally cleaner fuel than coal because it does not produce detrimental by-products such as sulfur, mercury, ash and particulates and because it provides twice the energy per unit of weight with half the carbon footprint during combustion. These points are not in dispute. However, in their recent publication in Climatic Change Letters, Howarth et al. (2011) report that their life-cycle evaluation of shale gas drilling suggests that shale gas has a larger GHG footprint than coal and that this larger footprint “undercuts the logic of its use as a bridging fuel over the coming decades”. We argue here that their analysis is seriously flawed in that they significantly overestimate the fugitive emissions associated with unconventional gas extraction, undervalue the contribution of “green technologies” to reducing those emissions to a level approaching that of conventional gas, base their comparison between gas and coal on heat rather than electricity generation (almost the sole use of coal), and assume a time interval over which to compute the relative climate impact of gas compared to coal that does not capture the contrast between the long residence time of CO2 and the short residence time of methane in the atmosphere. High leakage rates, a short methane GWP, and comparison in terms of heat content are the inappropriate bases upon which Howarth et al. ground their claim that gas could be twice as bad as coal in its greenhouse impact. Using more reasonable leakage rates and bases of comparison, shale gas has a GHG footprint that is half and perhaps a third that of coal.” Lawrence M. Cathles, Larry Brown, Milton Taam and Andrew Hunter, Climatic Change, DOI: 10.1007/s10584-011-0333-0. [Full text]

Methane and the greenhouse-gas footprint of natural gas from shale formations – Howarth et al. (2011) “We evaluate the greenhouse gas footprint of natural gas obtained by high-volume hydraulic fracturing from shale formations, focusing on methane emissions. Natural gas is composed largely of methane, and 3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the life-time of a well. These methane emissions are at least 30% more than and perhaps more than twice as great as those from conventional gas. The higher emissions from shale gas occur at the time wells are hydraulically fractured—as methane escapes from flow-back return fluids—and during drill out following the fracturing. Methane is a powerful greenhouse gas, with a global warming potential that is far greater than that of carbon dioxide, particularly over the time horizon of the first few decades following emission. Methane contributes substantially to the greenhouse gas footprint of shale gas on shorter time scales, dominating it on a 20-year time horizon. The footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20 years. Compared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years.” Robert W. Howarth, Renee Santoro and Anthony Ingraffea, Climatic Change, Volume 106, Number 4, 679-690, DOI: 10.1007/s10584-011-0061-5. [Full text]

Future development of the upstream greenhouse gas emissions from natural gas industry, focussing on Russian gas fields and export pipelines – Lechtenböhmer & Dienst (2010) “Natural gas makes an increasing contribution to the European Union’s energy supply. Due to its efficiency and low level of combustion emissions this reduces greenhouse gas emissions compared to the use of other fossil fuels. However, being itself a potent greenhouse gas, a high level of direct losses of natural gas in its process chain could neutralise these advantages. Which effect will finally prevail depends on future economical as well as technical developments. Based on two different scenarios of the main influencing factors we can conclude that over the next two decades CH4 emissions from the natural gas supply chain can be significantly reduced, in spite of unfavourable developments of the supply structures. This, however, needs a substantial, but economically attractive investment into new technology, particularly in Russia.” S. Lechtenböhmer, C. Dienst, Journal of Integrative Environmental Sciences, Volume 7, Issue S1, 2010, Pages 39 – 48, DOI: 10.1080/19438151003774463.

Study on Methane Emission Reduction Potential in China’s Oil and Natural Gas Industry – Liu et al. (2008) A review report of China’s situation with natural gas methane emissions. Junrong Liu and Jun Yao, Michael Gallaher and Jeff Coburn, Roger Fernandez, RTI Project Number 0208702.027, Prepared for U.S. EPA, April 2008. [Full text]

Tapping the leakages: Methane losses, mitigation options and policy issues for Russian long distance gas transmission pipelines – Lechtenböhmer et al. (2007) “The Russian natural gas industry is the world’s largest producer and transporter of natural gas. This paper aims to characterize the methane emissions from Russian natural gas transmission operations, to explain projects to reduce these emissions, and to characterize the role of emissions reduction within the context of current GHG policy. It draws on the most recent independent measurements at all parts of the Russian long distance transport system made by the Wuppertal Institute in 2003 and combines these results with the findings from the US Natural Gas STAR Program on GHG mitigation options and economics. With this background the paper concludes that the methane emissions from the Russian natural gas long distance network are approximately 0.6% of the natural gas delivered. Mitigating these emissions can create new revenue streams for the operator in the form of reduced costs, increased gas throughput and sales, and earned carbon credits. Specific emissions sources that have cost-effective mitigation solutions are also opportunities for outside investment for the Joint Implementation Kyoto Protocol flexibility mechanism or other carbon markets.” Stefan Lechtenböhmer, Carmen Dienst, Manfred Fischedick, Thomas Hanke, Roger Fernandez, Don Robinson, Ravi Kantamaneni and Brian Gillis, International Journal of Greenhouse Gas Control, Volume 1, Issue 4, October 2007, Pages 387-395, doi:10.1016/S1750-5836(07)00089-8.

Greenhouse gases: Low methane leakage from gas pipelines – Lelieveld et al. (2005) “Using natural gas for fuel releases less carbon dioxide per unit of energy produced than burning oil or coal, but its production and transport are accompanied by emissions of methane, which is a much more potent greenhouse gas than carbon dioxide in the short term. This calls into question whether climate forcing could be reduced by switching from coal and oil to natural gas1. We have made measurements in Russia along the world’s largest gas-transport system and find that methane leakage is in the region of 1.4%, which is considerably less than expected and comparable to that from systems in the United States. Our calculations indicate that using natural gas in preference to other fossil fuels could be useful in the short term for mitigating climate change.” J. Lelieveld, S. Lechtenböhmer, S. S. Assonov, C. A. M. Brenninkmeijer, C. Dienst, M. Fischedick & T. Hanke, Nature 434, 841-842 (14 April 2005) | doi:10.1038/434841a.

Estimating methane releases from natural gas production and transmission in Russia – Dedikov et al. (1999)
Abstract: Methane releases from the RAO Gazprom gas production and transmission facilities in Russia were determined in an extensive measurement program carried out in 1996 and 1997. Subsequently, the measurements were extrapolated to the Russian scale. The results show that methane releases from gas transmission are less than 1% of throughput. Methane loss from gas production in northwestern Siberia appears to be relatively small, generally less than 0.1%. The largest methane emissions result from venting during maintenance and repairs, leaks from valves on transmission lines, and from compressor stations. The measurements show that, in the case of leaks, a limited number of major ones accounts for most of the methane releases. Methane emissions expressed as a percentage of the gas volume produced or transported are (rounded figures): production and processing 0.1%, pipelines 0.2%, compressor stations 0.7%, so that the total release by production and transmission in Russia amounts to about 1.0%, i.e. ∼5.4×109 m3/a (∼4 Tg/a). This is consistent with our previous preliminary estimates, indicating that maximum emissions are 1.5–1.8%/a. However, this is generally lower than most other estimates and speculations.
Citation: J.V. Dedikov, G.S. Akopova (VNIIGaz), N.G. Gladkaja (VNIIGaz), A.S. Piotrovskij (Tyumentransgaz), V.A. Markellov (Volgotransgaz), S.S. Salichov (Yamburggazdabuicha), H. Kaesler, A. Ramm, A. Müller von Blumencron, J. Lelieveld (1999). Estimating methane releases from natural gas production and transmission in Russia, Atmospheric Environment, 33(20), 3291-3299,

Estimate of methane emissions from the U.S. natural gas industry – Kirchgessner et al. (1997) “Global methane emissions from the fossil fuel industries have been poorly quantified and, in many cases, emissions are not well-known even at the country level. Historically, methane emissions from the U.S. gas industry have been based on sparse data, incorrect assumptions, or both. As a result, the estimate of the contribution these emissions make to the global methane inventory could be inaccurate. For this reason the assertion that global warming could be reduced by replacing coal and oil fuels with natural gas could not be defended. A recently completed, multi year study conducted by the U.S. Environmental Protection Agency’s Office of Research and Development and the Gas Research Institute had the objective of determining methane emissions from the U.S. gas industry with an accuracy of t 0.5% of production. The study concluded that, in the 1992 base year, methane emissions from the industry were 314 t 105 Bscf or 6.04 t 2.01 Tg (all conversions to international units are made at 15.56 °C and 101.325 kPa)” David A. Kirchgessner, Robert A. Lott, R. Michael Cowgill, Matthew R. Harrison and Theresa M. Shires, Chemosphere, Volume 35, Issue 6, September 1997, Pages 1365-1390, doi:10.1016/S0045-6535(97)00236-1. [Full text]

Methane emission measurements in urban areas in Eastern Germany – Shorter et al. (1996) “We have investigated methane emissions from urban sources in the former East Germany using innovative measurement techniques including a mobile real-time methane instrument and tracer release experiments. Anthropogenic and biogenic sources were studied with the emphasis on methane emissions from gas system sources, including urban distribution facilities and a production plant. Methane fluxes from pressure regulating stations ranged from 0.006 to 24. l/min. Emissions from diffuse sources in urban areas were also measured with concentration maps and whole city flux experiments. The area fluxes of the two towns studied were 0.37 and 1.9 g/m2/s. The emissions from individual gas system stations and total town emissions of this study are comparable to results of similar sites examined in the United States.” Joanne H. Shorter, J. Barry Mcmanus, Charles E. Kolb, Eugene J. Allwine, Brian K. Lamb, Byard W. Mosher, Robert C. Harriss, Uwe Partchatka, Horst Fischer and Geoffrey W. Harris, et al., Journal of Atmospheric Chemistry, Volume 24, Number 2, 121-140, DOI: 10.1007/BF00162407. [Full text]

Indirect chemical effects of methane on climate warming – Lelieveld & Crutzen (1992) “METHANE concentrations in the atmosphere have increased from about 0.75 to 1.7 p.p.m.v. since pre-industrial times1,2. The current annual rate of increase of about 0.8% yr-1 (ref. 2) is due to increases in industrial and agricultural emissions. This increase in atmospheric methane concentrations not only influences the climate directly, but also indirectly through chemical reactions. Here we show that the climate effects of methane’s atmospheric chemistry have previously been overestimated, notably by the Inter-governmental Panel on Climate Change (IPCC)3, largely owing to neglect of the height dependence of certain atmospheric radiative processes. Using available estimates of fossil-fuel-related leaks of methane, our results show that switching from coal and oil to natural gas as an energy source would reduce climate warming. A significant fraction of methane emissions cannot, however, be accounted for by known sources; should leakages from gas production and distribution be underestimated for some countries, then it might be unwise to switch to using natural gas.” Jos Lelieveld & Paul J. Crutzen, Nature 355, 339 – 342 (23 January 1992); doi:10.1038/355339a0.

Gas leakage in United Kingdom – Wallis (1992) No abstract. M. K. Wallis, Nature 359, 355 (01 October 1992); doi:10.1038/359355a0.

Leaking gas in the greenhouse – Wallis (1991) “Greenhouse gas emissions by the United Kingdom could be significantly reduced by replacement of old and leaking gas mains. Such a programme could even be cost-effective for the utility concerned.” Max K. Wallis, Nature 354, 428 (12 December 1991); doi:10.1038/354428a0.

Leaky answer to greenhouse gas? – Wallis (1990) No abstract. Max K. Wallis, Nature 344, 25 – 26 (01 March 1990).

A study of leakage from the UK natural gas distribution system – Mitchell et al. (1990) “This paper studies leakage from the UK natural gas distribution system. British Gas maintains that the leakage rate is around 1% of supply. This paper estimates a Low, Medium and High Case leakage rate of 1.9%, 5.3% and 10.8% respectively. The authors are confident that the leakage rate is above 1.9% and consider it more likely that the leakage rate is between the Medium and High Case. This investigation has been very cautious in that only leakage from the low pressure, medium pressure and service pipelines has been calculated. No estimates of leakage from the broader supply system have been included because of lack of verifiable information. The implications of these leakage rates for energy policy are considered.” Catherine Mitchell, Jim Sweet and Tim Jackson, Energy Policy, Volume 18, Issue 9, November 1990, Pages 809-818, doi:10.1016/0301-4215(90)90060-H.

Methane leakage from natural gas – Okken (1990) “Carbon dioxide (CO2) emissions from fossil fuels are a major cause of the global greenhouse effect. Fuel switching is one of the options to reduce emissions. However, CO2 is not the only greenhouse gas. This paper addresses the question whether greenhouse effect mitigating strategies such as fuel switching would change if methane (CH4) is taken into account, by calculating the global warming from current energy related CH4 and CO (carbon monoxide) emissions as ‘CO2 equivalents’.” P. A. Okken, Energy Policy, Volume 18, Issue 2, March 1990, Pages 202-204.

Posted in Adaptation & Mitigation | 2 Comments »

New research from last week 14/2011

Posted by Ari Jokimäki on April 11, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news. Planet 3.0 also reports new research.

Published last week:

Positive climate feedback from boreal tundra expansion

Late Pliocene to Pleistocene sensitivity of the Greenland Ice Sheet in response to external forcing and internal feedbacks – Koenig et al. (2011) “The timing and nature of ice sheet variations on Greenland over the last ∼5 million years remain largely uncertain. Here, we use a coupled climate-vegetation-ice sheet model to determine the climatic sensitivity of Greenland to combined sets of external forcings and internal feedbacks operating on glacial-interglacial timescales. In particular, we assess the role of atmospheric pCO2, orbital forcing, and vegetation dynamics in modifying thresholds for the onset of glaciation in late Pliocene and Pleistocene. The response of circum-Arctic vegetation to declining levels of pCO2 (from 400 to 200 ppmv) and decreasing summer insolation includes a shift from boreal forest to tundra biomes, with implications for the surface energy balance. The expansion of tundra amplifies summer surface cooling and heat loss from the ground, leading to an expanded summer snow cover over Greenland. Atmospheric and land surface fields respond to forcing most prominently in late spring-summer and are more sensitive at lower Pleistocene-like levels of pCO2. We find cold boreal summer orbits produce favorable conditions for ice sheet growth, however simulated ice sheet extents are highly dependent on both background pCO2 levels and land-surface characteristics. As a result, late Pliocene ice sheet configurations on Greenland differ considerably from late Pleistocene, with smaller ice caps on high elevations of southern and eastern Greenland, even when orbital forcing is favorable for ice sheet growth.” Sebastian J. Koenig, Robert M. DeConto and David Pollard, Climate Dynamics, DOI: 10.1007/s00382-011-1050-0.

Positive climate feedback from boreal forest expansion

The effects of boreal forest expansion on the summer Arctic frontal zone – Liess et al. (2011) “Over the last 100 years, Arctic warming has resulted in a longer growing season in boreal and tundra ecosystems. This has contributed to a slow northward expansion of the boreal forest and a decrease in the surface albedo. Corresponding changes to the surface and atmospheric energy budgets have contributed to a broad region of warming over areas of boreal forest expansion. In addition, mesoscale and synoptic scale patterns have changed as a result of the excess energy at and near the surface. Previous studies have identified a relationship between the positioning of the boreal forest-tundra ecotone and the Arctic frontal zone in summer. This study examines the climate response to hypothetical boreal forest expansion and its influence on the summer Arctic frontal zone. Using the Weather Research and Forecasting model over the Northern Hemisphere, an experiment was performed to evaluate the atmospheric response to expansion of evergreen and deciduous boreal needleleaf forests into open shrubland along the northern boundary of the existing forest. Results show that the lower surface albedo with forest expansion leads to a local increase in net radiation and an average hemispheric warming of 0.6°C at and near the surface during June with some locations warming by 1–2°C. This warming contributes to changes in the meridional temperature gradient that enhances the Arctic frontal zone and strengthens the summertime jet. This experiment suggests that continued Northern Hemisphere high-latitude warming and boreal forest expansion might contribute to additional climate changes during the summer.” Stefan Liess, Peter K. Snyder and Keith J. Harding, Climate Dynamics, DOI: 10.1007/s00382-011-1064-7.

Synthesis of research on Arctic amplification

Processes and Impacts of Arctic Amplification: A Research Synthesis – Serreze & Barry (2011) “The past decade has seen substantial advances in understanding Arctic amplification – that trends and variability in surface air temperature tend to be larger in the Arctic region than for the Northern Hemisphere or globe as a whole. We provide a synthesis of research on Arctic amplification, starting with a historical context and then addressing recent insights into processes and key impacts, based on analysis of the instrumental record, modeling studies, and paleoclimate reconstructions. Arctic amplification is now recognized as an inherent characteristic of the global climate system, with multiple intertwined causes operating on a spectrum of spatial and temporal scales. These include, but are not limited to, changes in sea ice extent that impact heat fluxes between the ocean and the atmosphere, atmospheric and oceanic heat transports, cloud cover and water vapor that alter the longwave radiation flux to the surface, soot on snow and heightened black carbon aerosol concentrations. Strong warming over the Arctic Ocean during the past decade in autumn and winter, clearly associated with reduced sea ice extent, is but the most recent manifestation of the phenomenon. Indeed, periods of Arctic amplification are evident from analysis of both warm and cool periods over at least the past three million years. Arctic amplification being observed today is expected to become stronger in coming decades, invoking changes in atmospheric circulation, vegetation and the carbon cycle, with impacts both within and beyond the Arctic.” Mark C. Serreze and Roger G. Barry, Global and Planetary Change, doi:10.1016/j.gloplacha.2011.03.004.

Mediterranean warming most likely has anthropogenic origin

Consistency of observed near surface temperature trends with climate change projections over the Mediterranean region – Barkhordarian et al. (2011) “We examine the possibility that anthropogenic forcing (Greenhouse gases and Sulfate aerosols, GS) is a plausible explanation for the observed near-surface temperature trends over the Mediterranean area. For this purpose, we compare annual and seasonal observed trends in near-surface temperature over the period from 1980 to 2009 with the response to GS forcing estimated from 23 models derived from CMIP3 database. We find that there is less than a 5% chance that natural (internal) variability is responsible for the observed annual and seasonal area-mean warming except in winter. Using additionally two pattern similarity statistics, pattern correlation and regression, we find that the large-scale component (spatial-mean) of the GS signal is detectable (at 2.5% level) in all seasons except in winter. In contrast, we fail to detect the small-scale component (spatial anomalies about the mean) of GS signal in observed trend patterns. Further, we find that the recent trends are significantly (at 2.5% level) consistent with all the 23 GS patterns, except in summer and spring, when 9 and 5 models respectively underestimate the observed warming. Thus, we conclude that GS forcing is a plausible explanation for the observed warming in the Mediterranean region. Consistency of observed trends with climate change projections indicates that present trends may be understood of what will come more so in the future, allowing for a better communication of the societal challenges to meet in the future.” Armineh Barkhordarian, Jonas Bhend and Hans von Storch, Climate Dynamics, DOI: 10.1007/s00382-011-1060-y. [Full text]

Global sea ice retreats fastest in winter

Consistent changes in the sea ice seasonal cycle in response to global warming – Eisenman et al. (2011) “The Northern Hemisphere sea ice cover has diminished rapidly in recent years and is projected to continue to diminish in the future. The year-to-year retreat of Northern Hemisphere sea ice extent is faster in summer than winter, which has been identified as one of the most striking features of satellite observations as well as of state-of-the-art climate model projections. This is typically understood to imply that the sea ice cover is most sensitive to climate forcing in summertime, and previous studies have explained this by calling on factors such as the surface albedo feedback. However, in the Southern Hemisphere it is the wintertime sea ice extent that retreats fastest in climate model projections. Here, we show that the inter-hemispheric differences in the model projections can be attributed to differences in coastline geometry, which constrain where sea ice can occur. After accounting for coastline geometry, we find that the sea ice changes simulated in both hemispheres in most climate models are consistent with sea ice retreat being fastest in winter in the absence of landmasses. These results demonstrate that despite the widely differing rates of ice retreat among climate model projections, the seasonal structure of the sea ice retreat is robust among the models and uniform in both hemispheres.” Ian Eisenman, Tapio Schneider, David S. Battisti and Cecilia M. Bitz, Journal of Climate 2011, doi: 10.1175/2011JCLI4051.1.

They get wine earlier each year in Australia

Observed trends in winegrape maturity in Australia – Webb et al. (2011) “An extensive assessment of historical trends in winegrape maturity dates from vineyards located in geographically diverse winegrape growing regions in Australia has been undertaken. Records from 44 vineyard blocks, representing a range of varieties of Vitis vinifera L., were accessed. These comprise 33 short-term datasets (average 17 years in length) and 11 long-term datasets, ranging from 25 to 115 years in length (average 50 years). Time series of the day of the year grapes attain maturity were assessed. A trend to earlier maturity of winegrapes was observed in 43 of the 44 vineyard blocks. This trend was significant for six out of the 11 long-term blocks for the complete time period for which records were available. For the period 1993–2009, 35 of the 44 vineyard blocks assessed displayed a statistically significant trend to earlier maturity. The average advance in the phenology was dependent on the time period of observation, with a more rapid advance over more recent decades. Over the more recent 1993–2009 period the average advance was 1.7 days per year, whereas for the period 1985–2009 the rate of advance was 0.8 days per year on average in the 10 long-term vineyard blocks assessed for cross regional comparison. The trend to earlier maturity was associated with warming temperature trends for all of the blocks assessed in the study.” L. B. Webb, P. H. Whetton, E. W. R. Barlow, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02434.x.

Warming ocean reduces fish swimming ability

Increasing ocean temperature reduces the metabolic performance and swimming ability of coral reef damselfishes – Johansen & Jones (2011) “Tropical coral reef teleosts are exclusively ectotherms and their capacity for physical and physiological performance is therefore directly influenced by ambient temperature. This study examined the effect of increased water temperature to 3°C above ambient on the swimming and metabolic performance of 10 species of damselfishes (Pomacentridae) representing evolutionary lineages from 2 sub-families and 4 genera. Five distinct performance measures were tested: a) maximum swimming speed (Ucrit), b) gait-transition speed (the speed at which they change from strictly pectoral to pectoral-and-caudal swimming, Up−c), c) maximum aerobic metabolic rate (MO2−MAX), d) resting metabolic rate (MO2−REST), and e) aerobic scope (ratio of MO2−MAX to MO2−REST, ASC). Relative to the control (29°C), increased temperature (32°C) had a significant negative effect across all performance measures examined, with the magnitude of the effect varying greatly among closely related species and genera. Specifically, 5 species spanning three genera (Dascyllus, Neopomacentrus and Pomacentrus) showed severe reductions in swimming performance with Ucrit reduced in these species by 21.3–27.9% and Up−c by 32.6–51.3%. Furthermore, 5 species spanning all 4 genera showed significant reductions in metabolic performance with aerobic scope reduced by 24.3–64.9%. Comparisons of remaining performance capacities with field conditions indicate that 32°C water temperatures will leave multiple species with less swimming capacity than required to overcome the water flows commonly found in their respective coral reef habitats. Consequently, unless adaptation is possible, significant loss of species may occur if ocean warming of ≥3°C arises.” J. L. Johansen, G. P. Jones, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02436.x.

Yet another study showing accelerating Greenland mass loss

Greenland ice sheet mass balance: distribution of increased mass loss with climate warming; 2003-07 versus 1992-2002 – Zwally et al. (2011) “We derive mass changes of the Greenland ice sheet (GIS) for 2003-07 from ICESat laser altimetry and compare them with results for 1992-2002 from ERS radar and airborne laser altimetry. The GIS continued to grow inland and thin at the margins during 2003-07, but surface melting and accelerated flow significantly increased the marginal thinning compared with the 1990s. The net balance changed from a small loss of 7 ± 3 Gt a-1 in the 1990s to 171 ± 4 Gt a-1 for 2003-07, contributing 0.5 mm a-1 to recent global sea-level rise. We divide the derived mass changes into two components: (1) from changes in melting and ice dynamics and (2) from changes in precipitation and accumulation rate. We use our firn compaction model to calculate the elevation changes driven by changes in both temperature and accumulation rate and to calculate the appropriate density to convert the accumulation-driven changes to mass changes. Increased losses from melting and ice dynamics (17-206 Gt a-1) are over seven times larger than increased gains from precipitation (10-35 Gt a-1) during a warming period of ∼2 K (10 a)-1 over the GIS. Above 2000 m elevation, the rate of gain decreased from 44 to 28 Gt a-1, while below 2000 m the rate of loss increased from 51 to 198 Gt a-1. Enhanced thinning below the equilibrium line on outlet glaciers indicates that increased melting has a significant impact on outlet glaciers, as well as accelerating ice flow. Increased thinning at higher elevations appears to be induced by dynamic coupling to thinning at the margins on decadal timescales.” Zwally, H. Jay; Jun, L.I.; Brenner, Anita C.; Beckley, Matthew; Cornejo, Helen G.; Dimarzio, John; Giovinetto, Mario B.; Neumann, Thomas A.; Robbins, John; Saba, Jack L.; Donghui, Y.I.; Wang, Weili, Journal of Glaciology, Volume 57, Number 201, March 2011 , pp. 88-102(15).

Vegetation feedback’s minor influence to global temperature

Vegetation feedback under future global warming – Jiang et al. (2011) “It has been well documented that vegetation plays an important role in the climate system. However, vegetation is typically kept constant when climate models are used to project anthropogenic climate change under a range of emission scenarios in the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios. Here, an atmospheric general circulation model, and an asynchronously coupled system of an atmospheric and an equilibrium terrestrial biosphere model are forced by monthly sea surface temperature and sea ice extent for the periods 2051–2060 and 2090–2098 as projected with 17 atmosphere–ocean general circulation models participating in the IPCC Fourth Assessment Report, and by appropriate atmospheric carbon dioxide concentrations under the A2 emission scenario. The effects of vegetation feedback under future global warming are then investigated. It is found that the simulated composition and distribution of vegetation during 2051–2060 (2090–2098) differ greatly from the present, and global vegetation tends to become denser as expressed by a 21% (36%) increase in global mean leaf area index, which is most pronounced at the middle and high northern latitudes. Vegetation feedback has little effect on globally averaged surface temperature. On a regional scale, however, it induces statistically significant changes in surface temperature, in particular over most parts of continental Eurasia east of about 60°E where annual surface temperature is expected to increase by 0.1–1.0 K, with an average of about 0.4 K for each future period. These changes can mostly be explained by changes in surface albedo resulting from vegetation changes in the context of future global warming.” Dabang Jiang, Ying Zhang and Xianmei Lang, Theoretical and Applied Climatology, DOI: 10.1007/s00704-011-0428-6.

Evidence against cosmic ray driven ozone depletion

Do cosmic-ray-driven electron-induced reactions impact stratospheric ozone depletion and global climate change? – Grooss & Muller (2011) “Recently, the cosmic-ray-driven electron-induced reaction mechanism (CRE) was introduced to explain polar ozone depletion and surface temperature change. It was proposed that the dissociation of chlorofluorocarbons (CFCs) on ice surfaces of polar stratospheric clouds plays the dominant role in forming the ozone hole. Efforts have been made to predict polar ozone loss into future years. It was further proposed that CFCs and cosmic-ray driven ozone depletion may control global surface temperatures. These assertions challenge the fundamental understanding of Antarctic stratospheric ozone loss and global warming. Here we show that these arguments based on the CRE mechanism are inconclusive. First, correlations of satellite data of CFC-12, N2O and CH4 from ACE-FTS show no evidence of significant loss of CFC- 12 as predicted by the CRE mechanism. Second, conclusions drawn about a possible CRE impact on the atmosphere, based on correlations of different observed atmospheric parameters do not have a physical basis. Finally, predictions on the future development of the atmosphere based on these correlations for both the ozone hole or global surface temperatures are not reliable” Jens-Uwe Grooss and Muller Rolf, Atmospheric Environment, doi:10.1016/j.atmosenv.2011.03.059.

Lake levels rise in Tibet due to glacier melt

Monitoring lake level changes on the Tibetan Plateau using ICESat altimetry data (2003–2009) – Zhang et al. (2011) “In this study, ICESat altimetry data are used to provide precise lake elevations of the Tibetan Plateau (TP) during the period of 2003–2009. Among the 261 lakes examined ICESat data are available on 111 lakes: 74 lakes with ICESat footprints for 4–7 years and 37 lakes with footprints for 1–3 years. This is the first time that precise lake elevation data are provided for the 111 lakes. Those ICESat elevation data can be used as baselines for future changes in lake levels as well as for changes during the 2003–2009 period. It is found that in the 74 lakes (56 salt lakes) examined, 62 (i.e. 84%) of all lakes and 50 (i.e. 89%) of the salt lakes show tendency of lake level increase. The mean lake water level increase rate is 0.23 m/year for the 56 salt lakes and 0.27 m/year for the 50 salt lakes of water level increase. The largest lake level increase rate (0.80 m/year) found in this study is the lake Cedo Caka. The 74 lakes are grouped into four subareas based on geographical locations and change tendencies in lake levels. Three of the four subareas show increased lake levels. The mean lake level change rates for subareas I, II, III, IV, and the entire TP are 0.12, 0.26, 0.19, −0.11, and 0.2 m/year, respectively. These recent increases in lake level, particularly for a high percentage of salt lakes, supports accelerated glacier melting due to global warming as the most likely cause.” Guoqing Zhang, Hongjie Xie, Shichang Kang, Donghui Yi and Stephen F. Ackley, Remote Sensing of Environment, doi:10.1016/j.rse.2011.03.005.

It’s still not the sun

The Smithsonian solar constant data revisited: no evidence for a strong effect of solar activity in ground-based insolation data – Feulner (2011) “Apparent evidence for a strong signature of solar activity in ground-based insolation data was recently reported. In particular, a strong increase of the irradiance of the direct solar beam with sunspot number as well as a decline of the brightness of the solar aureole and the measured precipitable water content of the atmosphere with solar activity were presented. The latter effect was interpreted as evidence for cosmic-ray-induced aerosol formation. Here I show that these spurious results are due to a failure to correct for seasonal variations and the effects of volcanic eruptions and local pollution in the data. After correcting for these biases, neither the atmospheric water content nor the brightness of the solar aureole show any significant change with solar activity, and the variations of the solar-beam irradiance with sunspot number are in agreement with previous estimates. Hence there is no evidence for the influence of solar activity on the climate being stronger than currently thought.” Feulner, G., Atmos. Chem. Phys., 11, 3291-3301, doi:10.5194/acp-11-3291-2011, 2011. [Full text]

Posted in Climate science | 1 Comment »

New research from last week 13/2011

Posted by Ari Jokimäki on April 4, 2011

Here is the new research published last week. I’m not including everything that was published but just some papers that got my attention. Those who follow my Facebook page (and/or Twitter) have already seen most of these, as I post these there as soon as they are published. Here, I’ll just put them out in one batch. Sometimes I might also point out to some other news as well, but the new research will be the focus here. Here’s the archive for the news of previous weeks. By the way, if this sort of thing interests you, be sure to check out A Few Things Illconsidered, they have a weekly posting containing lots of links to new research and other climate related news. Planet 3.0 also reports new research.

Published last week:

Planetary albedo decreases when planet warms

Atmospheric and surface contributions to planetary albedo – Donohoe & Battisti (2011) “The planetary albedo is partitioned into a component due to atmospheric reflection and a component due to surface reflection by using shortwave fluxes at the surface and top of the atmosphere in conjunction with a simple radiation model. The vast majority of the observed global average planetary albedo (88%) is due to atmospheric reflection. Surface reflection makes a relatively small contribution to planetary albedo because the atmosphere attenuates the surface contribution to planetary albedo by a factor of approximately three. The global average planetary albedo in the ensemble average of the CMIP3 pre-industrial simulations is also primarily (87%) due to atmospheric albedo. The inter-model spread in planetary albedo is relatively large and is found to be predominantly a consequence of inter-model differences in atmospheric albedo, with surface processes playing a much smaller role despite significant inter-model differences in surface albedo. The CMIP3 models show a decrease in planetary albedo under a doubling of carbon dioxide – also primarily due to changes in atmospheric reflection (which explains more than 90% of the inter-model spread). All models show a decrease in planetary albedo due to the lowered surface albedo associated with a contraction of the cryosphere in a warmer world, but this effect is small compared to the spread in planetary albedo due to model differences in the change in clouds.” Aaron Donohoe and David S. Battisti, Journal of Climate 2011, doi: 10.1175/2011JCLI3946.1. [Full text]

Antarctic thermostat for global deepwater

On the linkage between Antarctic surface-water stratification and global deepwater temperature – Keeling & Visbeck (2011) “The suggestion is advanced that the remarkably low static stability of Antarctic surface waters may arise from a feedback loop involving global deepwater temperatures. If deepwater temperatures are too warm, this promotes Antarctic convection, thereby strengthening the inflow of Antarctic Bottom Water into the ocean interior and cooling the deep ocean. If deepwaters are too cold, this promotes Antarctic stratification allowing the deep ocean to warm because of the input of North Atlantic Deep Water. A steady-state deepwater temperature is achieved such that the Antarctic surface can barely undergo convection. A two-box model is used to illustrate this feedback loop in its simplest expression and to develop basic concepts, such as the bounds on the operation of this loop. The model illustrates the possible dominating influence of Antarctic upwelling rate and Antarctic freshwater balance on global deepwater temperatures.” Ralph F. Keeling, Martin Visbeck, Journal of Climate 2011, doi: 10.1175/2011JCLI3642.1. [Full text]

Environmental reconstruction from intestinal contents of baby mammoth

Environmental Reconstruction Inferred From The Intestinal Contents Of The Yamal Baby Mammoth Lyuba (Mammuthus Primigenius Blumenbach, 1799) – Kosintsev et al. (2011) “The article presents the results of a complex investigation of the intestinal content of the frozen mummy of a baby woolly mammoth (Mammuthus primigenius Blumenbach, 1799) found in 2007 in the Yamal Peninsula (Western Siberia). The mummy belongs to a female mammoth calf approximately 1–1.5 months of age, and it has been named “Lyuba”. Analysis of bone tissue yielded a 14C date of 41910 (+550/-450) years ago. Analysis of detritus material from the large intestine yielded a 14C date of 41700 (+700/-550) years ago. These dates practically coincide, thus denoting synchronism of the time of the baby mammoth’s death and the formation of its intestinal contents. This time correspond to the middle part of MIS-3, or the Middle Weichselian Pleniglacial. Pollen, phytolith, plant macrofossil and mineral analyses of the intestinal content were carried out. Reconstruction of the environment where the baby mammoth lived is given based on the intestinal content analyses. The data suggest that the baby mammoth lived in tundra-like landscapes dominated by grass-sedge communities with forbs and Betula nana.” Pavel A. Kosintsev, Elena G. Lapteva, Svetlana S. Trofimova, Oksana G. Zanina, Aleksey N. Tikhonov and Johannes Van der Plicht, Quaternary International, doi:10.1016/j.quaint.2011.03.027.

Proglacial lake discharges near the beginning of YD event

Timing and duration of North American glacial lake discharges and the Younger Dryas climate reversal – Rayburn et al. (2011) “Radiocarbon-dated sediment cores from the Champlain Valley (northeastern USA) contain stratigraphic and micropaleontologic evidence for multiple, high-magnitude, freshwater discharges from North American proglacial lakes to the North Atlantic. Of particular interest are two large, closely spaced outflows that entered the North Atlantic Ocean via the St. Lawrence estuary about 13,200–12,900 cal yr BP, near the beginning of the Younger Dryas cold event. We estimate from varve chronology, sedimentation rates and proglacial lake volumes that the duration of the first outflow was less than 1 yr and its discharge was approximately 0.1 Sv (1 Sverdrup = 106 m3 s−1). The second outflow lasted about a century with a sustained discharge sufficient to keep the Champlain Sea relatively fresh for its duration. According to climate models, both outflows may have had sufficient discharge, duration and timing to affect meridional ocean circulation and climate. In this report we compare the proglacial lake discharge record in the Champlain and St. Lawrence valleys to paleoclimate records from Greenland Ice cores and Cariaco Basin and discuss the two-step nature of the inception of the Younger Dryas.” John A. Rayburn, Thomas M. Cronin, David A. Franzi, Peter L.K. Knuepfer and Debra A. Willard, Quaternary Research, doi:10.1016/j.yqres.2011.02.004.

Climate change and forest shifts in Siberia

Climate change and climate-induced hot spots in forest shifts in central Siberia from observed data – Tchebakova et al. (2011) “Regional Siberian studies have already registered climate warming over the last several decades. We evaluated ongoing climate change in central Siberia between 1991 and 2010 and a baseline period, 1961–1990, and between 1991 and 2010 and Hadley 2020 climate change projections, represented by the moderate B1 and severe A2 scenarios. Our analysis showed that winters are already 2–3°C warmer in the north and 1–2°C warmer in the south by 2010. Summer temperatures increased by 1°C in the north and by 1–2°C in the south. Change in precipitation is more complicated, increasing on average 10% in middle latitudes and decreasing 10–20% in the south, promoting local drying in already dry landscapes. Hot spots of possible forest shifts are modeled using our Siberian bioclimatic vegetation model and mountain vegetation model with respect to climate anomalies observed pre-2010 and predicted 2020 Hadley scenarios. Forests are predicted to shift northwards along the central Siberian Plateau and upslope in both the northern and southern mountains. South of the central Siberian Plateau, steppe advancement is predicted that was previously non-existent north of 56°N latitude. South of 56°N, steppe expansion is predicted in the dry environments of Khakasiya and Tyva. In the southern mountains, it is predicted that the lower tree line will migrate upslope due to increased dryness in the intermontane Tyvan basins. The hot spots of vegetation change that are predicted by our models are confirmed by regional literature data.” N. M. Tchebakova, E. I. Parfenova and A. J. Soja, Regional Environmental Change, DOI: 10.1007/s10113-011-0210-4.

Below ground ecosystem in high Arctic not yet affected by global warming

A high arctic soil ecosystem resists long-term environmental manipulations – Lamb et al. (2011) “We evaluated above and below ground ecosystem changes in a 16 year, combined fertilization and warming experiment in a High Arctic tundra deciduous shrub heath (Alexandra Fiord, Ellesmere Island, NU, Canada). Soil emissions of the three key greenhouse gases (carbon dioxide, methane, and nitrous oxide) were measured in mid July 2009 using soil respiration chambers attached to a FTIR system. Soil chemical and biochemical properties including Q10 values for CO2, CH4, and N2O, Bacteria and Archaea assemblage composition, and the diversity and prevalence of key nitrogen cycling genes including bacterial amoA, crenarchaeal amoA, and nosZ were measured. Warming and fertilization caused strong increases in plant community cover and height but had limited effects on greenhouse gas fluxes and no substantial effect on soil chemistry or biochemistry. Similarly, there was a surprising lack of directional shifts in the soil microbial community as a whole or any change at all in microbial functional groups associated with CH4 consumption or N2O cycling in any treatment. Thus, it appears that while warming and increased nutrient availability have strongly affected the plant community over the last 16 years, the below ground ecosystem has not yet responded. This resistance of the soil ecosystem has resulted in limited changes in greenhouse gas fluxes in response to the experimental treatments.” Eric G. Lamb, Sukkyun Han, Brian D. Lanoil, Greg H. R. Henry, Martin E. Brummell, Samiran Banerjee, Steven D. Siciliano, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02431.x.

Willow tit and its caterpillar food synchronized better due to climate change

Warming climate advances breeding and improves synchrony of food demand and food availability in a boreal passerine – Vatka et al. (2011) “Global climate change affects ecosystems via several trophic levels. We investigated changes in the timing of breeding in the willow tit (Poecile montanus) and timing of its caterpillar food resource in relation to warming springs in a boreal forest. We used generalized linear mixed effect models to study the importance of synchrony between the timing of breeding in willow tits and the caterpillar food availability on the breeding success, measured as nestling survival rate and mean nestling weight. Both the timing of breeding and the timing of the caterpillar peak advanced during the last decades, and were well explained by spring temperatures. Unlike in most passerine populations studied, synchrony has improved with rising spring temperatures. However, it had only a modest although statistically significant positive influence on breeding success. Spring temperatures do not seem to be used as cues for the timing of caterpillar food availability by willow tits. We conclude that responses to climatic warming seem to be population, species and habitat specific, necessitating research in a wide range of taxa in different climatic zones.” Emma Vatka, Markku Orell, Seppo Rytkönen, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02430.x.

Greenland ice sheet might melt faster than expected

The Greenland Ice Sheet Response to Transient Climate Change – Ren et al. (2011) “This study applies a multi-phase, multiple-rheology, scalable and extensible geofluid model to the Greenland Ice Sheet (GrIS). The model is driven by monthly atmospheric forcing from global climate model simulations. Novel features of the model, referred to as SEGMENT-Ice, include using the full Navier-Stokes equations to account for non-local dynamic balance and its influence on ice flow; and a granular sliding layer between the bottom ice layer and the lithosphere layer to provide a mechanism for possible large scale surges in a warmer future climate (granular basal layer is for certain specific region, though). Monthly climate of SEGMENT-Ice allows an investigation of detailed features such as seasonal melt area extent (SME) over Greenland. The model reproduced reasonably well the annual maximum SME and total ice mass lost rate when compared observations from the Special Sensing Microwave Imager (SSM/I) and Gravity Recovery and Climate Experiment (GRACE) over the past few decades. The SEGMENT-Ice simulations are driven by projections from two relatively high-resolution climate models, the NCAR-CCSM3 and MIROC3.2-hires models, under a realistic 21st century greenhouse gas emission scenario. They suggest that the surface flow would be enhanced over the entire GrIS, due to a reduction of ice viscosity as the temperature increases, despite of small change in the ice surface topography over the interior of Greenland. With increased surface flow speed, strain-heating induces more rapid heating in the ice at levels deeper than due to diffusion alone. Basal sliding, especially for granular sediments, provides an efficient mechanism for fast-glacier acceleration and enhanced mass loss. This mechanism, absent from other models, provides a rapid dynamic response to climate change. Net mass loss estimates from the new model should reach ~220 km3/yr by 2100, significantly higher than estimates by the IPCC AR4 of ~50–100 km3/yr. By 2100, the perennial frozen surface area decreases up to ~60%; to ~7×105 km2, indicating a massive expansion of the ablation zone. Ice mass change patterns, particularly along the periphery, are very similar between the two climate models.” Diandong Ren, Rong Fu, Lance M. Leslie, Jianli Chen, Clark R. Wilson and David J. Karoly, Journal of Climate 2011, doi: 10.1175/2011JCLI3708.1.

Spectral measurements of CO2 and CH4 concentrations

Long-term analysis of carbon dioxide and methane column-averaged mole fractions retrieved from SCIAMACHY – Schneising et al. (2011) “Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic greenhouse gases contributing to global climate change. SCIAMACHY onboard ENVISAT (launch 2002) was the first and is now with TANSO onboard GOSAT (launch 2009) one of only two satellite instruments currently in space whose measurements are sensitive to CO2 and CH4 concentration changes in the lowest atmospheric layers where the variability due to sources and sinks is largest. We present long-term SCIAMACHY retrievals (2003–2009) of column-averaged dry air mole fractions of both gases (denoted XCO2 and XCH4) derived from absorption bands in the near-infrared/shortwave-infrared (NIR/SWIR) spectral region focusing on large-scale features. The results are obtained using an upgraded version (v2) of the retrieval algorithm WFM-DOAS including several improvements, while simultaneously maintaining its high processing speed. The retrieved mole fractions are compared to global model simulations (CarbonTracker XCO2 and TM5 XCH4) being optimised by assimilating highly accurate surface measurements from the NOAA/ESRL network and taking the SCIAMACHY averaging kernels into account. The comparisons address seasonal variations and long-term characteristics. The steady increase of atmospheric carbon dioxide primarily caused by the burning of fossil fuels can be clearly observed with SCIAMACHY globally. The retrieved global annual mean XCO2 increase agrees with CarbonTracker within the error bars (1.80±0.13 ppm yr−1 compared to 1.81±0.09 ppm yr−1). The amplitude of the XCO2 seasonal cycle as retrieved by SCIAMACHY, which is 4.3±0.2 ppm for the Northern Hemisphere and 1.4±0.2 ppm for the Southern Hemisphere, is on average about 1 ppm larger than for CarbonTracker. An investigation of the boreal forest carbon uptake during the growing season via the analysis of longitudinal gradients shows good agreement between SCIAMACHY and CarbonTracker concerning the overall magnitude of the gradients and their annual variations. The analysis includes a discussion of the relative uptake strengths of the Russian and North American boreal forest regions. The retrieved XCH4 results show that after years of stability, atmospheric methane has started to rise again in recent years which is consistent with surface measurements. The largest increase is observed for the tropics and northern mid- and high-latitudes amounting to about 7.5±1.5 ppb yr−1 since 2007. Due care has been exercised to minimise the influence of detector degradation on the quantitative estimate of this anomaly.” Schneising, O., Buchwitz, M., Reuter, M., Heymann, J., Bovensmann, H., and Burrows, J. P., Atmos. Chem. Phys., 11, 2863-2880, doi:10.5194/acp-11-2863-2011, 2011. [full text]

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