Extreme weather may be signs of climate change |
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2010/08/12/MNLL1ET3B7.DTL
Floods, fires, melting ice and feverish heat: From smoke-choked Moscow to water-soaked Iowa and the High Arctic, the planet seems to be having a midsummer breakdown. It's not just a portent of things to come, scientists say, but a sign of troubling climate change already under way.
The weather-related cataclysms of July and August fit patterns predicted by climate scientists, the Geneva-based World Meteorological Organization says - although those scientists always shy from tying individual disasters directly to global warming.
The experts now see an urgent need for better ways to forecast extreme events like Russia's heat wave and wildfires and the record deluge devastating Pakistan. They'll discuss such tools in meetings this month and next in Europe and America, under United Nations, U.S. and British government sponsorship.
"There is no time to waste," because societies must be equipped to deal with global warming, says British government climatologist Peter Stott.
He said modelers of climate systems are "very keen" to develop supercomputer modeling that would enable more detailed linking of cause and effect as a warming world shifts jet streams and other atmospheric currents. Those changes can wreak weather havoc.
The United Nation's network of climate scientists - the Intergovernmental Panel on Climate Change - has long predicted that rising global temperatures would produce more frequent and intense heat waves, and more intense rainfalls. In its latest assessment, in 2007, the Nobel Prize-winning panel went beyond that. It said these trends "have already been observed," in an increase in heat waves since 1950, for example.
Still, climatologists generally refrain from blaming warming for this drought or that flood, since so many other factors also affect the day's weather.
Stott and NASA's Gavin Schmidt, at the Goddard Institute of Space Studies in New York, say it's better to think in terms of odds: Warming might double the chances for heat waves, for example. "That is exactly what's happening," Schmidt said, "a lot more warm extremes and less cold extremes."
The WMO pointed out that this summer's events fit the international scientists' projections of "more frequent and more intense extreme weather events due to global warming."
Worldwide temperature readings show that this January-June was the hottest first half of a year since record-keeping began in the mid-19th century. Meteorologists say 17 nations have recorded all-time-high temperatures in 2010, more than in any other year.
Scientists blame the warming on carbon dioxide and other heat-trapping gases pouring into the atmosphere from power plants, cars and trucks, furnaces and other fossil fuel-burning industrial and residential sources.
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