Global warming to raise US temperatures by 10 degrees by 2080 From our ANI Correspondent Washington, May 10: A new study by NASA scientists has suggested that greenhouse-gas warming may raise average summer temperatures in the eastern United States by nearly 10 degrees Fahrenheit by the 2080s.
"There is the potential for extremely hot summertime temperatures in the future, especially during summers with less-than-average frequent rainfall," said Barry Lynn of NASA's Goddard Institute for Space Studies and Columbia University, New York.
The research found that eastern US summer daily high temperatures that currently averaged in the low-to-mid-80s (degrees Fahrenheit) were mostly likely to soar into the low-to-mid-90s during typical summers by the 2080s.
"In extreme seasons - when precipitation falls infrequently - July and August daily high temperatures could average between 100 and 110 degrees Fahrenheit in cities such as Chicago, Washington, and Atlanta," said Lynn.
As part of the study, the researchers analyzed nearly 30 years of observational temperature and precipitation data and used computer model simulations that considered soil, atmospheric, and oceanic conditions to project changes in greenhouse gases.
The global model, one of the models used in the recently issued climate report by the Intergovernmental Panel on Climate Change (IPCC), developed by NASA's Goddard Institute for Space Studies, was used to identify future changes in large-scale atmospheric circulation patterns due to the build up of greenhouse gases.
The information was then fed into the weather prediction model to forecast summer-to-summer temperature variability in the eastern United States during the 2080s.
The weather model showed that extreme summertime surface temperatures developed when carbon dioxide emissions were assumed to continue to increase about two percent a year, the "business as usual" scenario.
According to the researchers, the weather prediction model used in this research is advantageous as it assesses details about future climate at a smaller geographic scale than global models, providing reliable simulations not only on the amounts of summer precipitation, but also on its frequency and timing.
"This is an important capability for predicting summer temperatures because observed daily temperatures are usually higher on rainless days and when precipitation falls less frequently than normal," said Lynn.
"Observational climate data also showed that sea surface temperatures in the Pacific Ocean have a significant influence on summer air temperatures in the eastern US," he added.
"Relatively cool waters in the eastern Pacific often result in stubborn summer high-pressure systems over the eastern states that block storms, reducing the frequency of precipitation below normal," said study co-author Richard Healy of the Woods Hole Oceanographic Institution, Woods Hole, Massachusetts.
"Less frequent storms result in higher surface and atmospheric temperatures that then feedback on the atmospheric circulation to further reduce storm frequency and raise surface temperatures even more," Healy added.
The study is published in the April 2007 issue of the American Meteorological Society's Journal of Climate.
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