Catastrophic Blizzards, Heat Waves and Floods: Global Warming or Just Crazy Weather?

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Officially it's not even winter yet, but freakish 60-mile-an-hour blizzards and frigid temperatures have already walloped the Pacific Northwest, while record a-foot-in-a-day snows hit the Northern Plains and Rockies. With improbable weather becoming routine, forecasters may be in for another wild ride this winter.

There's no way of knowing exactly when or where extreme cold or heavy snow is going to hit during the next three months, but the forecast does call for a 100 percent chance of someone -- most likely a Republican who wants to gut environmental regulation -- seizing on such weather as proof that the planet isn't warming.

Last February, as the snow just kept piling up in Washington, D.C., Sen. Jim Inhofe, R-Okla., and his family built an igloo down the street from the Capitol and labeled it "Al Gore's new home." And the Virginia Republican Party ran TV ads telling viewers to call legislators who supported climate-change legislation "and tell them how much global warming you get this weekend. Maybe they'll come help you shovel."

Of course, the "Snowmageddon" jokesters had no way of knowing at the time that within less than five months the snowshoe would be on the other foot. By early July, with much of North America broiling in record-shattering heat, most climate-change holdouts were keeping a low profile. (But not Inhofe, who defiantly lectured a sweating ABC News team, "We're in a cycle now that all the scientists agree is going into a cooling period.")

Meanwhile, some environmental groups pointed to the blistering July temperatures as confirmation that we've headed over the cliff of global climate change. The National Wildlife Foundation rushed out a report supplement titled "Extreme Heat in Summer 2010: A Window on the Future," filling it with pictures of sweating city-dwellers and hot-colored charts. The Natural Resources Defense Council put out a press release in which its climate-center director announced, "Welcome to what might be termed 'the dark side of climate change.'"

Back in the 1990s, the major environmental groups made a decision not to highlight extreme weather events as early signs of global warming. Should they have stuck to that policy? When heatwaves, droughts and floods are exhibited as evidence of climate disruption, does it make it that much easier for people like Inhofe to whip up more confusion the next time a winter storm hits? Is there any cool-headed way to talk about the crazy climate of recent years?

The odds on odd weather

Given the complexity of climate science, it's not surprising that the best way to get the attention of the media and the public is to talk about exceptional weather that's happening right now rather than the bigger threat of long-term climate disruption. But that makes life difficult for those who study climate for a living.

One such researcher is Katharine Hayhoe, an associate professor at Texas Tech University. She sees a clear necessity to come back hard against fatuous arguments that, she says, go something like, "Well, you know, temperatures are cooling in the month of September in Erie, Pennsylvania, so how can the planet be warming?" But, she warns, climate scientists have to be careful themselves not to go beyond the data: "It is very tempting to seize on a single dramatic event, but we have to stay true to what we know, to stick to terms like 'consistent with' and 'risk of.'"

In public statements, most climate scientists are indeed careful to stress that we cannot draw conclusions from individual extreme weather events. But Michael Mann, director of the Earth System Science Center at Penn State University, is now thinking such caution may have gone too far.