Extreme Weather Expected to Worsen

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WASHINGTON  — Freakish weather disasters — from the sudden October snowstorm in the Northeast U.S. to the record floods in Thailand — are striking more often. And global warming is likely to spawn more similar weather extremes at a huge cost, says a draft summary of an international climate report obtained by The Associated Press. [Read about the areas with the most disasters.]

The final draft of the report from a panel of the world's top climate scientists paints a wild future for a world already weary of weather catastrophes costing billions of dollars. The report says costs will rise and perhaps some locations will become "increasingly marginal as places to live."

The report from the Nobel Prize-winning Intergovernmental Panel on Climate Change will be issued in a few weeks, after a meeting in Uganda. It says there is at least a 2-in-3 probability that climate extremes have already worsened because of man-made greenhouse gases.

This marks a change in climate science from focusing on subtle changes in daily average temperatures to concentrating on the harder-to-analyze freak events that grab headlines, cause economic damage and kill people. The most recent bizarre weather extreme, the pre-Halloween snowstorm, is typical of the damage climate scientists warn will occur — but it's not typical of the events they tie to global warming.

"The extremes are a really noticeable aspect of climate change," said Jerry Meehl, senior scientist at the National Center for Atmospheric Research. "I think people realize that the extremes are where we are going to see a lot of the impacts of climate change."

The snow-bearing Nor'easter cannot be blamed on climate change and probably isn't the type of storm that will increase with global warming, four meteorologists and climate scientists said. They agree more study is needed. But experts on extreme storms have focused more closely on the increasing numbers of super-heavy rainstorms, not snow, NASA climate scientist Gavin Schmidt said.

The opposite kind of disaster — the drought in Texas and the Southwest U.S. — is also the type of event scientists are saying will happen more often as the world warms, said Schmidt and Meehl, who reviewed part of the climate panel report. No studies have specifically tied global warming to the drought, but it is consistent with computer models that indicate current climate trends will worsen existing droughts, Meehl said. [Vote: Should the U.S. Get Rid of FEMA , as Ron Paul Suggests?]

Studies also have predicted more intense monsoons with climate change. Warmer air can hold more water and puts more energy into weather systems, changing the dynamics of storms and where and how they hit.

Thailand is now coping with massive flooding from monsoonal rains that illustrate how climate is also interconnected with other manmade issues such as population and urban development, river management and sinking lands, Schmidt said. In fact, the report says that "for some climate extremes in many regions, the main driver for future increases in losses will be socioeconomic in nature" rather than greenhouse gases.

There's an 80 percent chance that the killer Russian heat wave of 2010 wouldn't have happened without the added push of global warming, according to a study published last week in the Proceedings of the National Academy of Sciences. [Read Susan Milligan: Earthquake Reaction Shows DC Unprepared for Terror Attack]

So while in the past the climate change panel, formed by the United Nations and World Meteorological Organization, has discussed extreme events in snippets in its report, this time the scientists are putting them all together. The report, which needs approval by diplomats at the mid-November meeting, tries to measure the confidence scientists have in their assessment of climate extremes both future and past.

Chris Field, one of the leaders of the climate change panel, said he and other authors won't comment because the report still is subject to change. The summary chapter of the report didn't detail which regions of the world might suffer extremes so severe as to leave them marginally habitable.