Heat Waives

ClimateWire reports that heatwaves have outpaced coldspells by 2:1 over the past decade:

But how much of the heat can be blamed on climate change?

“We can’t say that one individual or even two heat waves are due to global warming,” said David Easterling, a climatologist with NOAA’s National Climatic Data Center. “But what we can say is that warming temperatures do increase the probability of a heat wave.”

Scientists have documented a pronounced warming trend in the United States and around the world over the last several decades. In its 2007 report, the Intergovernmental Panel on Climate Change concluded with 90 percent certainty that human-caused greenhouse gas emissions have been the primary factor in Earth’s overall temperature rise since 1950.

Meanwhile, the World Meteorological Organization said late last year that the 2000-2009 decade appears to be the warmest since record-keeping began in the 1850s.

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Record highs outnumbered record lows 2-to-1 over the last decade, and the study — published in Geophysical Research Letters last year — predicted that disparity could balloon to 20-to-1 by the end of this century without sharp curbs on greenhouse gas emissions.

While it’s impossible to pin blame for one heat wave on climate change, since naturally occurring weather patterns like El Niño can magnify or counteract human-caused warming over short periods, experts said an emerging crop of studies suggests that heat waves will become more frequent and intense without strong cuts in greenhouse gas emissions.

Gazoinga. 20-to-1? Yipes. But that raises the question: will it actually count as a heat wave if the climate has shifted? If the climate shifts, that’s just the way things are, we get a new baseline.

I’m sure Roger will have something incisive to say about this.