The Heat, The Fires, The Flooding: Is Climate Change To Blame?

By Eyder Peralta

Published July 10, 2012 at 4:12 PM CDT

People enjoy the view from a lifeguard structure as the sun sets at Seal Beach, south of Los Angeles, California on Monday. Much of the U.S. has been gripped by a relentless heatwave, sparking health warnings and sending people to makeshift cooling shelters.

Every time there's been a bout of severe weather, like the heat wave in the northeast, the wild fires in the west and flooding across the U.K, the talk, naturally, turns to climate change.

The big question: How much does global warming have to do with severe weather?

The Guardian has a story today that states unequivocally that "climate change researchers have been able to attribute recent examples of extreme weather to the effects of human activity on the planet's climate systems for the first time, marking a major step forward in climate research."

Here's the money graph:

"Last year's record warm November in the UK – the second hottest since records began in 1659 – was at least 60 times more likely to happen because of climate change than owing to natural variations in the earth's weather systems, according to the peer-reviewed studies by the National Oceanic and Atmospheric Administration in the US, and the Met Office in the UK. The devastating heatwave that blighted farmers in Texas in the US last year, destroying crop yields in another record "extreme weather event", was about 20 times more likely to have happened owing to climate change than to natural variation."

As you can tell, the answer is pretty nuanced. Over at The Washington Post, the Capital Weather Gang has an easier to understand — albeit not peer-reviewed — explanation. They talked to a research meteorologist at NOAA's Earth System Research Laboratory. Specifically they were talking about the latest heatwave and Martin Hoerling was asked if climate change had anything to do with it.

It's likely, Hoerling said.

"[O]n the heat wave story. Sometimes you'll see 'that heat wave was due to climate change' That's not a very accurate statement, not a very helpful statement. But it's not entirely untrue either," he said. "It may well be that 90 percent of [a given] heat wave was natural, but that the 10 percent that pushed it to record proportions was due to climate change."

In other words, the heatwave may not be triggered by climate change, but its intensity certainly could be.

Hoerling added that his statement is a "defensible scientific statement."