AGW Observer

Observations of anthropogenic global warming

New research from last week 9/2011

Posted by Ari Jokimäki on March 7, 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:

New global CO2 emission time series

Monthly, global emissions of carbon dioxide from fossil fuel consumption – Andres et al. (2011) “This paper examines available data, develops a strategy, and presents a monthly, global time series of fossil-fuel carbon dioxide emissions for the years 1950 to 2006. This monthly time series was constructed from detailed study of monthly data from the 21 countries that account for approximately 80% of global total emissions. These data were then used in a Monte Carlo approach to proxy for all remaining countries. The proportional-proxy methodology estimates by fuel group the fraction of annual emissions emitted in each country and month. Emissions from solid, liquid, and gas fuels are explicitly modeled by the proportional-proxy method. The primary conclusion from this study is the global monthly time series is statistically significantly different from a uniform distribution throughout the year. Uncertainty analysis of the data presented show that the proportional-proxy method used faithfully reproduces monthly patterns in the data and the global monthly pattern of emissions is relatively insensitive to the exact proxy assignments used. The data and results presented here should lead to a better understanding of global and regional carbon cycles, especially when the mass data are combined with the stable carbon isotope data in atmospheric transport models.” R. J. Andres, J. S. Gregg, L. Losey, G. Marland, T. A. Boden, Tellus B, 2011, DOI: 10.1111/j.1600-0889.2011.00530.x.

Clouds not credible as Faint Young Sun Paradox resolvers

Clouds and the Faint Young Sun Paradox – Goldblatt & Zahnle (2011) “We investigate the role which clouds could play in resolving the Faint Young Sun Paradox (FYSP). Lower solar luminosity in the past means that less energy was absorbed on Earth (a forcing of −50 W m−2 during the late Archean), but geological evidence points to the Earth having been at least as warm as it is today, with only very occasional glaciations. We perform radiative calculations on a single global mean atmospheric column. We select a nominal set of three layered, randomly overlapping clouds, which are both consistent with observed cloud climatologies and reproduced the observed global mean energy budget of Earth. By varying the fraction, thickness, height and particle size of these clouds we conduct a wide exploration of how changed clouds could affect climate, thus constraining how clouds could contribute to resolving the FYSP. Low clouds reflect sunlight but have little greenhouse effect. Removing them entirely gives a forcing of +25 W m−2 whilst more modest reduction in their efficacy gives a forcing of +10 to +15 W m−2. For high clouds, the greenhouse effect dominates. It is possible to generate +50 W m−2 forcing from enhancing these, but this requires making them 3.5 times thicker and 14 K colder than the standard high cloud in our nominal set and expanding their coverage to 100% of the sky. Such changes are not credible. More plausible changes would generate no more than +15 W m−2 forcing. Thus neither fewer low clouds nor more high clouds can provide enough forcing to resolve the FYSP. Decreased surface albedo can contribute no more than +5 W m−2 forcing. Some models which have been applied to the FYSP do not include clouds at all. These overestimate the forcing due to increased CO2 by 20 to 25% when pCO2 is 0.01 to 0.1 bar.” Goldblatt, C. and Zahnle, K. J.: Clouds and the Faint Young Sun Paradox, Clim. Past, 7, 203-220, doi:10.5194/cp-7-203-2011, 2011. [full text]

Deep ocean heat important for global heat balance

Deep ocean heat content changes estimated from observation and reanalysis product and their influence on sea level change – Kouketsu et al. (2011) “We calculated basin-scale and global ocean decadal temperature change rates from the 1990s to the 2000s for waters below 3000 m. Large temperature increases were detected around Antarctica, and a relatively large temperature increase was detected along the northward path of Circumpolar Deep Water in the Pacific. The global heat content (HC) change estimated from the temperature change rates below 3000 m was 0.8 × 1022 J decade−1; a value that cannot be neglected for precise estimation of the global heat balance. We reproduced the observed temperature changes in the deep ocean using a data assimilation system and examined virtual observations in the reproduced data field to evaluate the uncertainty of the HC changes estimated from the actual temporally and spatially sparse observations. From the analysis of the virtual observations, it is shown that the global HC increase below 3000 m during recent decades can be detected using the available observation system of periodic revisits to the same sampling sections, although the uncertainty is large.” Kouketsu, S., et al. (2011), J. Geophys. Res., 116, C03012, doi:10.1029/2010JC006464. [full text]

Greenland and Antarctic ice mass losses are accelerating

Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise – Rignot et al. (2011) “Ice sheet mass balance estimates have improved substantially in recent years using a variety of techniques, over different time periods, and at various levels of spatial detail. Considerable disparity remains between these estimates due to the inherent uncertainties of each method, the lack of detailed comparison between independent estimates, and the effect of temporal modulations in ice sheet surface mass balance. Here, we present a consistent record of mass balance for the Greenland and Antarctic ice sheets over the past two decades, validated by the comparison of two independent techniques over the last 8 years: one differencing perimeter loss from net accumulation, and one using a dense time series of time-variable gravity. We find excellent agreement between the two techniques for absolute mass loss and acceleration of mass loss. In 2006, the Greenland and Antarctic ice sheets experienced a combined mass loss of 475 ± 158 Gt/yr, equivalent to 1.3 ± 0.4 mm/yr sea level rise. Notably, the acceleration in ice sheet loss over the last 18 years was 21.9 ± 1 Gt/yr2 for Greenland and 14.5 ± 2 Gt/yr2 for Antarctica, for a combined total of 36.3 ± 2 Gt/yr2. This acceleration is 3 times larger than for mountain glaciers and ice caps (12 ± 6 Gt/yr2). If this trend continues, ice sheets will be the dominant contributor to sea level rise in the 21st century.” Rignot, E., I. Velicogna, M. R. van den Broeke, A. Monaghan, and J. Lenaerts (2011), Geophys. Res. Lett., 38, L05503, doi:10.1029/2011GL046583. [full text]

Measuring London’s carbon dioxide emissions

Controls of carbon dioxide concentrations and fluxes above central London – Helfter et al. (2011) “Eddy-covariance measurements of carbon dioxide fluxes were taken continuously between October 2006 and May 2008 at 190 m height in central London (UK) to quantify emissions and study their controls. Inner London, with a population of 8.2 million (~5000 inhabitants per km2) is heavily built up with 8% vegetation cover within the central boroughs. CO2 emissions were found to be mainly controlled by fossil fuel combustion (e.g. traffic, commercial and domestic heating). The measurement period allowed investigation of both diurnal patterns and seasonal trends. Diurnal averages of CO2 fluxes were found to be correlated with traffic but also exhibited an inverse dependency on atmospheric stability in the near-neutral range, with higher fluxes coinciding with unstable stratification during most seasons and perhaps reflecting how changes in heating-related natural gas consumption and, to a lesser extent, photosynthetic activity controlled the seasonal variability. Despite measurements being taken at ca. 22 times the mean building height, coupling with street level was adequate, especially during daytime. Night-time saw a higher occurrence of stable or neutral stratification, especially in autumn and winter, which resulted in data loss in post-processing and caused the tower to become decoupled from street level. CO2 fluxes observed at night were not always correlated with traffic counts, probably reflecting this decoupling, but also the fact that at night heating was always a larger source than traffic. No significant difference was found between the annual estimate of net exchange of CO2 for the expected measurement footprint and the values derived from the National Atmospheric Emissions Inventory (NAEI), with daytime fluxes differing by only 3%. This agreement with NAEI data also supported the use of the simple flux footprint model which was applied to the London site; this also suggests that individual roughness elements did not significantly affect the measurements due to the large ratio of measurement height to mean building height.” Helfter, C., Famulari, D., Phillips, G. J., Barlow, J. F., Wood, C. R., Grimmond, C. S. B., and Nemitz, E., Atmos. Chem. Phys., 11, 1913-1928, doi:10.5194/acp-11-1913-2011, 2011. [full text]

Native American Records of Weather and Climate

Waniyetu Wówapi: Native American Records of Weather and Climate – Therrell & Trotter (2011) “Pictographic calendars called Waniyetu wówapi or ‘winter counts’ kept by several Great Plains Indian cultures (principally the Sioux or Lakota peoples) preserve a record of events important to these peoples from roughly the 17th through 19th centuries. A number of these memorable events include natural phenomena such as meteor storms, eclipses, and unusual weather and climate. Examination of a selection of the available winter count records and related interpretive writings indicates that the Lakota and other native Plains cultures recorded many instances of unusual weather or climate and associated impacts. Analysis of the winter count records in conjunction with observational and proxy climate records and other historical documentation suggests that the winter counts preserve a unique record of some of the most unusual and severe climate events of the early American period and provide valuable insight into the impacts upon people and their perceptions of such events in the ethnographically important region of the Great Plains.” Matthew D. Therrell, Makayla J. Trotter, Bulletin of the American Meteorological Society 2011. [full text]

Hottest spot of Earth is in Iran’s Lut Desert

Satellite Finds Highest Land Skin Temperatures on Earth – Mildrexler et al. (2011) Without abstract. The hottest spots of the Earth are being located in this study. David J. Mildrexler, Maosheng Zhao, Steven W. Running, Bulletin of the American Meteorological Society 2011. [full text]

Rainfall causing Pakistan floods should have happened in India

Anomalous Atmospheric Events Leading to the Summer 2010 Floods in Pakistan – Houze et al. (2011) “The development of a highly anomalous pressure pattern brought rainstorms of a type that normally occur in the region of Bangladesh into the arid mountainous region of Pakistan.” R. A. Houze, Jr., K. L. Rasmussen, S. Medina, S. R. Brodzik, and U. Romatschke, Bulletin of the American Meteorological Society 2011. [full text]

Negative SW cloud feedback in Fennoscandia during last 1000 years

Cloud response to summer temperatures in Fennoscandia over the last thousand years – Gagen et al. (2011) “Cloud cover is one of the most important factors controlling the radiation balance of the Earth. The response of cloud cover to increasing global temperatures represents the largest uncertainty in model estimates of future climate because the cloud response to temperature is not well-constrained. Here we present the first regional reconstruction of summer sunshine over the past millennium, based on the stable carbon isotope ratios of pine treerings from Fennoscandia. Comparison with the regional temperature evolution reveals the Little Ice Age (LIA) to have been sunny, with cloudy conditions in the warmest periods of the Medieval at this site. A negative shortwave cloud feedback is indicated at high latitude. A millennial climate simulation suggests that regionally low temperatures during the LIA were mostly maintained by a weaker greenhouse effect due to lower humidity. Simulations of future climate that display a negative shortwave cloud feedback for high-latitudes are consistent with our proxy interpretation.” Gagen, M., E. Zorita, D. McCarroll, G. H. F. Young, H. Grudd, R. Jalkanen, N. J. Loader, I. Robertson, and A. Kirchhefer (2011), Geophys. Res. Lett., 38, L05701, doi:10.1029/2010GL046216.

Madden–Julian Oscillation might get more active in future

Will global warming modify the activity of the Madden–Julian Oscillation? – Jones & Carvalho (2011) “The Madden–Julian Oscillation (MJO) is the most prominent form of tropical intraseasonal variability in the climate system. Observations suggest that warming in the tropical Indian and Pacific Oceans in recent decades may have contributed to increased trends in the annual number of MJO events. A stochastic model is used to project changes in MJO activity under a global warming scenario. The mean number of events per year may rise from ∼3.9 (1948–2008) to ∼5.7 (2049–2099) and the probability of very active years (5 or more events) may significantly increase from 0.51 ± 0.01 (1990–2008) to 0.75 ± 0.01 (2010–2027) and 0.92 ± 0.01 (2094–2099).” Charles Jones, Leila M. V. Carvalho, Quarterly Journal of the Royal Meteorological Society, 2011, DOI: 10.1002/qj.765.

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