How hot was it?
Posted: Mon Oct 04, 2010 12:19 am
http://earthobservatory.nasa.gov/IOTD/view.php?id=46159 wrote: <<An unparalleled heat wave in eastern Europe, coupled with intense droughts and fires in Russia, put Earth’s temperatures in the headlines this summer. Likewise, an exceptionally warm July in the eastern United States strained power grids, forced nursing home evacuations, and slowed transit systems. But from a global perspective, how warm was it? And was global warming the cause of the unusual heat waves? Scientists at NASA’s Goddard Institute for Space Studies (GISS), led by James Hansen, released an analysis that addressed these questions.The global maps above show temperature anomalies; that is, how temperatures in June through August 2010 differed from the mean temperatures from 1951-1980. Shades of red represent warmer than normal temperatures, with blues depicting cooler.
The intensity of the Russian heat wave exceeded anything scientists have seen in the temperature record since widespread global temperature measurements became available in the 1880s. But can global warming cause such extreme weather events? The answer—both no and yes—is not simple. Weather within a given region occurs in such a complex and unstable environment, driven by such a multitude of factors that no single weather event can be pinned solely on climate change. However, if you frame the question differently—Would an event like the Moscow heat wave have occurred if carbon dioxide levels had remained at pre-industrial levels? —the answer, Hansen asserted, is clear. “Almost certainly not.” The frequency of extreme weather events increases disproportionately as global temperatures rise. “Were global temperature not increasing, ” he said, “the chance of an extreme heat wave such as the one Moscow experienced, though not impossible, would be vanishingly small.”) >>
