Tuesday, April 17, 2012

The Weekend of 100 Tornadoes: Are Killer Storms Being Fueled by Climate Change?

It could have been so much worse. Over 100 tornadoes ripped through several Plains states in just 24 hours over the weekend. Cars were tossed through the air and houses were pulverized. Hail the size of baseballs fell from the sky, crushing anything left in the open. More than what is ordinarily a month's worth of cyclones struck in a single day, yet miraculously, only one, in the Oklahoma town of Westwood, proved fatal, killing six victims who lived in and around a mobile-trailer park. "God was merciful," Kansas Governor Sam Brownback told CNN on Sunday.

But it wasn't just God or chance. The low death toll was also due to a faster and more insistent warning system by weather forecasters, who put the word out early and often and over many platforms that the past weekend could be a dangerous one for the Midwest, thanks to an unusually strong storm system. The National Weather Service's Storm Prediction Center took the unusual step of alerting people in the region more than a day before what was termed a possible "high-end, life-threatening event." Warnings went out over radios, smart phones and TVs, urging people to stay underground or in a tornado shelter for the duration of the storm. And with memories of the more than 500 people who died in cyclones last year still fresh, residents in the affected areas paid attention and stayed out of harm's way.

In the age of climate change, a lot of science and press coverage have been given over to determining whether warming really does make extreme events like heat waves, floods, storms or tornadoes more frequent or more powerful. That's understandable: gradual warming over years or decades doesn't get a lot of attention, but a megastorm like Hurricane Katrina in 2005 or the bursts of killer tornadoes last spring certainly do. It's not just a matter of focusing public attention, however; extreme-weather events kill tens of thousands of people every year, and take a sizable chunk out of the global economy — not something anyone's likely to fail to notice. Last year the U.S. experienced a dozen natural disasters that caused a billion or more dollars in damages, ranging from Hurricane Irene in September to the lingering drought in Texas and the Southwest. If climate change is really supercharging extreme weather — causing death and mayhem — that's one more reason to get a grip on carbon emissions fast.

As it happens, the U.N.'s Intergovernmental Panel on Climate Change published an assessment on the science of extreme weather and global warming just last month — but the answers are cloudy. The panel found that it was likely that man-made carbon emissions are leading to extreme heat, something that should resonate on an April day that was so unseasonably hot that runners were warned away from the Boston Marathon. There was also medium confidence that carbon emissions and other anthropogenic factors are leading to more extreme rainfall — like the Pakistan floods of 2010 — and more intense droughts, like the one much of the U.S. is suffering through right now. More