Is Global Warming Causing the Heatwave?

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For years, climate scientists have been a study in extreme caution. Whenever a heatwave gripped some part of the world (like New York in 2006 or Europe in 2003), media types would call up science types and ask: "is this global warming?"

…to which the scientist would almost invariably respond: "Climate is not weather. While models suggest that rising carbon dioxide levels will lead to more frequent bouts of intense heat, individual heatwaves are controlled by a range of factors that have nothing to do with climate change," etc.

But evidence is piling up quickly that extreme heat — like the blistering temperatures now descended across the eastern United States this week — can indeed be attributed to human-induced global warming. And it's making scientists' natural penchant for caution increasingly untenable. Herewith, Tom Peterson's recent comments to The Project on Climate Science:

“We’re getting a dramatic taste of the kind of weather we are on course to bequeath to our grandchildren,” says Tom Peterson, Chief Scientist for NOAA’s National Climatic Data Center.

Global warming deniers are sure to come flying from the nearest dark

corner to cry "foul!" with some comment like, "every time there's a

snowstorm, you say it doesn't disprove global warming, but then every

time there's a heatwave, you say it PROVES global warming!"

Let's

just head them off at the pass: there is some serious weight behind these claims.

First, it's not just heat. global warming has weighted the dice in favor of extreme rainfall events, too, including the floods that rocked Tennessee and Kentucky this spring. Witness Kevin Trenberth of the National Center for Atmospheric Research speaking recently to Joe Romm of Climate Progress:

There is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It’s about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms and it’s unfortunate that the public is not associating these with the fact that this is one manifestation of climate change. And the prospects are that these kinds of things will only get bigger and worse in the future.

And as Romm pointed out in his epic post yesterday, the ratio of record highs in the U.S. to record lows has been steadily increasing for decades. Even if one ignores the fact that 2010 is on pace to set a new high for the the hottest year on record — that's for the whole planet, much of which is also experiencing record heat — the overarching trend is pretty convincing:

Some of Romm's post is reproduced above, but you really should read the whole thing in order to fully understand the argument that we are currently experiencing global warming. The effects aren't relegated to the year 2100 or some future that we can pretend will never come. They're here. Now

And if we don't drastically change our behavior as a civilization soon, they're going to get worse.

Source: Climate Progess