AGW Observer

Observations of anthropogenic global warming

New research from last week 38/2011

Posted by Ari Jokimäki on September 26, 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.

Tuvalu has experienced very rapid sea level rise since 1950

Sea Level Variations at Tropical Pacific Islands since 1950 – Becker et al. (2011) “The western tropical Pacific is usually considered as one of the most vulnerable region of the world under present-day and future global warming. It is often reported that some islands of the region already suffer significant sea level rise. To clarify the latter concern, in the present study we estimate sea level rise and variability since 1950 in the western tropical Pacific region (20°S-15°N; 120°E-135°W). We estimate the total rate of sea level change at selected individual islands, as a result of climate variability and change, plus vertical ground motion where available. For that purpose, we reconstruct a global sea level field from 1950 to 2009, combining long (over 1950–2009) good quality tide gauge records with 50-year-long (1958–2007) gridded sea surface heights from the Ocean General Circulation Model DRAKKAR. The results confirm that El Niño-Southern Oscillation (ENSO) events have a strong modulating effect on the interannual sea level variability of the western tropical Pacific, with lower/higher-than-average sea level during El Niño/La Niña events, of the order of ± 20–30 cm. Besides this sub-decadal ENSO signature, sea level of the studied region also shows low-frequency (multi decadal) variability which superimposes to, thus in some areas amplifies current global mean sea level rise due to ocean warming and land ice loss. We use GPS precise positioning records whenever possible to estimate the vertical ground motion component that is locally superimposed to the climate-related sea level components. Superposition of global mean sea level rise, low-frequency regional variability and vertical ground motion shows that some islands of the region suffered significant ‘total’ sea level rise (i.e., that felt by the population) during the past 60 years. This is especially the case for the Funafuti Island (Tuvalu) where the “total” rate of rise is found to be about 3 times larger than the global mean sea level rise over 1950–2009.” M. Becker, B. Meyssignac, C. Letetrel, W. Llovel, A. Cazenave, T. Delcroix, Global and Planetary Change, doi:10.1016/j.gloplacha.2011.09.004.

Sea level might rise 1.8 to 5.5 meters by 2500

Sea level projections to AD2500 with a new generation of climate change scenarios – Jevrejeva et al. (2011) “Sea level rise over the coming centuries is perhaps the most damaging side of rising temperature (Anthoff et al, 2009). The economic costs and social consequences of coastal flooding and forced migration will probably be one of the dominant impacts of global warming (Sugiyama et al, 2008). To date, however, few studies (Anthoff et al, 2009; Nicholls et al, 2008) on infrastructure and socio-economic planning include provision for multi-century and multi-meter rises in mean sea level. Here we use a physically plausible sea level model constrained by observations, and forced with four new Representative Concentration Pathways (RCP) radiative forcing scenarios (Moss et al, 2010) to project median sea level rises of 0.57 for the lowest forcing and 1.10 m for the highest forcing by 2100 which rise to 1.84 and 5.49 m respectively by 2500. Sea level will continue to rise for several centuries even after stabilization of radiative forcing with most of the rise after 2100 due to the long response time of sea level. The rate of sea level rise would be positive for centuries, requiring 200–400 years to drop to the 1.8 mm/yr 20th century average, except for the RCP3PD which would rely on geoengineering.” S. Jevrejeva, J.C. Moore, A. Grinsted, Global and Planetary Change, doi:10.1016/j.gloplacha.2011.09.006.

Decrease of breeding range predicted for most of European birds

The fate of European breeding birds under climate, land-use and dispersal scenarios – Barbet-Massin et al. (2011) “Many species have already shifted their distributions in response to recent climate change. Here, we aimed at predicting the future breeding distributions of European birds under climate, land-use and dispersal scenarios. We predicted current and future distributions of 409 species within an ensemble forecast framework using seven species distribution models (SDMs), five climate scenarios and three emission and land-use scenarios. We then compared results from SDMs using climate-only variables, habitat-only variables or both climate and habitat variables. In order to account for a species’ dispersal abilities, we used natal dispersal estimates and developed a probabilistic method that produced a dispersal scenario intermediate between the null and full dispersal scenarios generally considered in such studies. We then compared results from all scenarios in terms of future predicted range changes, range shifts and variations in species richness. Modeling accuracy was better with climate-only variables than with habitat-only variables, and better with both climate and habitat variables. Habitat models predicted smaller range shifts and smaller variations in range size and species richness than climate models. Using both climate and habitat variables, it was predicted that the range of 71% of the species would decrease by 2050, with a 335km median shift. Predicted variations in species richness showed large decreases in the southern regions of Europe, as well as increases, mainly in Scandinavia and northern Russia. The partial dispersal scenario was significantly different from the full dispersal scenario for 25% of the species, resulting in the local reduction of the future predicted species richness of up to 10%. We concluded that the breeding range of most European birds will decrease in spite of dispersal abilities close to a full dispersal hypothesis, and that given the contrasted predictions obtained when modeling climate change only and land-use change only, both scenarios must be taken into consideration.” Morgane Barbet-Massin, Wilfried Thuiller, Frédéric Jiguet, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02552.x.

2010 was a record year for Greenland melt extent

Greenland ice sheet surface melt extent and trends: 1960-2010 – Mernild et al. (2011) “Observed meteorological data and a high-resolution (5 km) model were used to simulate Greenland ice sheet surface melt extent and trends before the satellite era (1960-79) and during the satellite era through 2010°. The model output was compared with passive microwave satellite observations of melt extent. For 1960-2010 the average simulated melt extent was 15 ± 5%. For the period 1960-72, simulated melt extent decreased by an average of 6%, whereas 1973-2010 had an average increase of 13%, with record melt extent in 2010. The trend in simulated melt extent since 1972 indicated that the melt extent in 2010 averaged twice that in the early 1970s. The maximum and mean melt extents for 2010 were 52% (∼9.5 × 105 km2) and 28% (∼5.2 × 105 km2), respectively, due to higher-than-average winter and summer temperatures and lower-than-average winter precipitation. For 2010, the southwest Greenland melt duration was 41-60 days longer than the 1960-2010 average, while the northeast Greenland melt duration was up to 20 days shorter. From 1960 to 1972 the melting period (with a >10% melt extent) decreased by an average of 3 days a−1. After 1972, the period increased by an average of 2 days a−1, indicating an extended melting period for the ice sheet of about 70 days: 40 and 30 days in spring and autumn, respectively.” Mernild, Sebastian H.; Mote, Thomas L.; Liston, Glen E., Journal of Glaciology, Volume 57, Number 204, September 2011 , pp. 621-628(8), DOI: 10.3189/002214311797409712.

Record warm years are at least 4x more likely due to mankind

The contribution of anthropogenic forcings to regional changes in temperature during the last decade – Christidis et al. (2011) “Regional distributions of the mean annual temperature in the 2000s are computed with and without the effect of anthropogenic influences on the climate in several sub-continental regions. Simulated global patterns of the temperature response to external forcings are regressed against observations using optimal fingerprinting. The global analysis provides constraints which are then used to construct the regional temperature distributions. A similar approach was also employed in previous work, but here the methodology is extended to examine changes in any region, including areas with a poor observational coverage that were omitted in the earlier study. Two different General Circulation Models (GCMs) are used in the analysis. Anthropogenic forcings are found to have at least quadrupled the likelihood of occurrence of a year warmer than the warmest year since 1900 in 23 out of the 24 regions. The temperature distributions computed with the two models are very similar. While a more detailed assessment of model dependencies remains to be made once additional suitable GCM simulations become available, the present study introduces the statistical methodology and demonstrates its first application. The derived information concerning the effect of human influences on the regional climate is useful for adaptation planning. Moreover, by pre-computing the change in the likelihood of exceeding a temperature threshold over a range of thresholds, this kind of analysis enables a near real-time assessment of the anthropogenic impact on the observed regional temperatures.” Nikolaos Christidis, Peter A. Stott, Francis W. Zwiers, Hideo Shiogama and Toru Nozawa, Climate Dynamics, DOI: 10.1007/s00382-011-1184-0.

Urbanization decreases diurnal temperature range

Urbanization effect on the diurnal temperature range: different roles under solar dimming and brightening – Wang et al. (2011) “Based on the 1960~2009 meteorological data from 559 stations over China, the urbanization effect on the diurnal temperature range (DTR) was evaluated in this study. Different roles of urbanization were specially detected under solar dimming and solar brightening. During the solar dimming time, both urban and rural stations showed decreasing trends in maximum temperature(Tmax) due to decreased radiation, suggesting that dimming effects are not only evident in urbanized areas, but also in rural areas. Minimum temperature (Tmin), however, increased more substantially in urban areas than in rural areas over the dimming period, resulting in greater decrease in DTR in the urban areas. When the radiation reversed from dimming to brightening, the change in the DTR became different. The Tmax increased faster in rural areas, suggesting that the brightening could be much stronger in rural areas than it in urban areas. Similar trends of Tmin between urban and rural appeared during the brightening period. Urban DTR continued to show a decreasing trend due to the urbanization effect while the rural DTR presented an increasing trend. The remarkable DTR difference in the urban and rural areas showed a significant urbanization effect in the solar brightening time.” Kai Wang, Hong Ye, Feng Chen, Yongzhu Xiong and Cuiping Wang, Journal of Climate 2011, doi: 10.1175/JCLI-D-10-05030.1.

Recent increase in cosmic rays has not increased cloudiness

Relationship of Lower Troposphere Cloud Cover and Cosmic Rays: An Updated Perspective – Agee et al. (2011) “An updated assessment has been made of the proposed hypothesis that “galactic cosmic rays (GCRs) are positively correlated with lower troposphere global cloudiness.” A brief review of the many conflicting studies that attempt to prove or disprove this hypothesis is also presented. It has been determined in this assessment that the recent extended quiet period (QP) between solar cycles 23–24 has led to a record high level of GCRs, which in turn has been accompanied by a record low level of lower troposphere global cloudiness. This represents a possible observational disconnect, and the update presented here continues to support the need for further research on the GCR-Cloud hypothesis and its possible role in the science of climate change.” Ernest M. Agee, Kandace Kiefer and Emily Cornett, Journal of Climate 2011, doi: 10.1175/JCLI-D-11-00169.1.

Tropical ants have less warming tolerance than high latitude ants

Who likes it hot? A global analysis of the climatic, ecological, and evolutionary determinants of warming tolerance in ants – Diamond et al. (2011) “Effects of climate warming on wild populations of organisms are expected to be greatest at higher latitudes, paralleling greater anticipated increases in temperature in these regions. Yet, these expectations assume that populations in different regions and taxa are equally susceptible to the effects of warming. This is unlikely to be the case. Here, we develop a series of predictive models for physiological thermal tolerances in ants based on current and future climates. We found that tropical ants have lower warming tolerances, a metric of susceptibility to climate warming, than temperate ants despite greater increases in temperature at higher latitudes. Using climatic, ecological and phylogenetic data, we refine our predictions of which ants (across all regions) were most susceptible to climate warming. We found that ants occupying warmer and more mesic forested habitats at lower elevations are the most physiologically susceptible to deleterious effects of climate warming. Phylogenetic history was also a strong indicator of physiological susceptibility. In short, we find that ants that live in the canopies of hot, tropical forest are the most at risk, globally, from climate warming. Unfortunately this is where many, perhaps most, ant and other species on Earth live.” Sarah E. Diamond, D. Magdalena Sorger, Jiri Hulcr, Shannon L. Pelini, Israel Del Toro, Christopher Hirsch, Erik Oberg, Robert R. Dunn, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02542.x.

Climate change has already decreased rice yield in India

Climate change, the monsoon, and rice yield in India – Auffhammer et al. (2011) “Recent research indicates that monsoon rainfall became less frequent but more intense in India during the latter half of the Twentieth Century, thus increasing the risk of drought and flood damage to the country’s wet-season (kharif) rice crop. Our statistical analysis of state-level Indian data confirms that drought and extreme rainfall negatively affected rice yield (harvest per hectare) in predominantly rainfed areas during 1966–2002, with drought having a much greater impact than extreme rainfall. Using Monte Carlo simulation, we find that yield would have been 1.7% higher on average if monsoon characteristics, especially drought frequency, had not changed since 1960. Yield would have received an additional boost of nearly 4% if two other meteorological changes (warmer nights and lower rainfall at the end of the growing season) had not occurred. In combination, these changes would have increased cumulative harvest during 1966–2002 by an amount equivalent to about a fifth of the increase caused by improvements in farming technology. Climate change has evidently already negatively affected India’s hundreds of millions of rice producers and consumers.” Maximilian Auffhammer, V. Ramanathan and Jeffrey R. Vincent, Climatic Change, DOI: 10.1007/s10584-011-0208-4.

Temperature extremes become common even with 2 degree global warming

Intensification of seasonal extremes given a 2°C global warming target – Anderson (2011) “Current international efforts to reduce greenhouse gas emissions and limit human-induced global-mean near-surface temperature increases to 2°C, relative to the pre-industrial era, are intended to avoid possibly significant and dangerous impacts to physical, biological, and socio-economic systems. However, it is unknown how these various systems will respond to such a temperature increase because their relevant spatial scales are much different than those represented by numerical global climate models—the standard tool for climate change studies. This deficiency can be addressed by using higher-resolution regional climate models, but at great computational expense. The research presented here seeks to determine how a 2°C global-mean temperature increase might change the frequency of seasonal temperature extremes, both in the United States and around the globe, without necessarily resorting to these computationally-intensive model experiments. Results indicate that in many locations the regional temperature increases that accompany a 2°C increase in global mean temperatures are significantly larger than the interannual-to-decadal variations in seasonal-mean temperatures; in these locations a 2°C global mean temperature increase results in seasonal-mean temperatures that consistently exceed the most extreme values experienced during the second half of the 20th Century. Further, results indicate that many tropical regions, despite having relatively modest overall temperature increases, will have the most substantial increase in number of hot extremes. These results highlight that extremes very well could become the norm, even given the 2°C temperature increase target.” Bruce T. Anderson, Climatic Change, DOI: 10.1007/s10584-011-0213-7.

Ice cover season has shortened for Northern Hemisphere lakes

Extreme events, trends, and variability in Northern Hemisphere lake-ice phenology (1855–2005) – Benson et al. (2011) “Often extreme events, more than changes in mean conditions, have the greatest impact on the environment and human well-being. Here we examine changes in the occurrence of extremes in the timing of the annual formation and disappearance of lake ice in the Northern Hemisphere. Both changes in the mean condition and in variability around the mean condition can alter the probability of extreme events. Using long-term ice phenology data covering two periods 1855–6 to 2004–5 and 1905–6 to 2004–5 for a total of 75 lakes, we examined patterns in long-term trends and variability in the context of understanding the occurrence of extreme events. We also examined patterns in trends for a 30-year subset (1975–6 to 2004–5) of the 100-year data set. Trends for ice variables in the recent 30-year period were steeper than those in the 100- and 150-year periods, and trends in the 150-year period were steeper than in the 100-year period. Ranges of rates of change (days per decade) among time periods based on linear regression were 0.3−1.6 later for freeze, 0.5−1.9 earlier for breakup, and 0.7−4.3 shorter for duration. Mostly, standard deviation did not change, or it decreased in the 150-year and 100-year periods. During the recent 50-year period, standard deviation calculated in 10-year windows increased for all ice measures. For the 150-year and 100-year periods changes in the mean ice dates rather than changes in variability most strongly influenced the significant increases in the frequency of extreme lake ice events associated with warmer conditions and decreases in the frequency of extreme events associated with cooler conditions.” Barbara J. Benson, John J. Magnuson, Olaf P. Jensen, Virginia M. Card, Glenn Hodgkins, Johanna Korhonen, David M. Livingstone, Kenton M. Stewart, Gesa A. Weyhenmeyer and Nick G. Granin, Climatic Change, DOI: 10.1007/s10584-011-0212-8.

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2 Responses to “New research from last week 38/2011”

  1. Jesús R. said

    Wow! Very interesting ones, here, thanks! :)

  2. Ari Jokimäki said

    Yes, sometimes there are many interesting papers during a week and sometimes there is less of the more interesting ones. I think I even skipped a few relatively interesting ones during last week because there were so many other interesting papers.

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