Wednesday, August 13, 2014

On Top of Withering Drought, California Smashes Heat Records

Los Angeles City Street Services Field Engineering Aide Winston Chu drinks cold water as his crew paves streets under a heat wave in May. (Credit: AP / Damian Dovarganes) Click to enlarge.
Caught in a withering drought, California is also shattering a 120-year-old record for heat.

For the first half of 2014, the state has been an average of 4.6 degrees Fahrenheit warmer than normal, and 1 degree warmer than the previous record set in 1934, according to the National Climatic Data Center.

“In the business of climate science, this is a shattering of a record,” said Jonathan Overpeck, of the University of Arizona’s Institute of the Environment.  As for what’s driving this unprecedented heat, Overpeck told the Palm Springs Desert Sun, “We are fairly certain that the unusual warmth is mostly due to human-caused global warming.”

California’s current drought, Overpeck added, is a “global warming drought” and a harbinger of things to come.

The number of planetary wave resonance events is shown as grey bars for each 4-year interval. While there used to be one or two events in a 4-year period, 2004-2007 saw three such events and 2008-2011 even five events. For comparison the red curve shows the change in Arctic temperature relative to that in the remainder of the Northern Hemisphere. Since 2000, the Arctic has warmed much faster than other latitudes.  [Credit: Potsdam Institute for Climate Impact Research (PIK)] Click to enlarge.
A new study by German climate scientists reports that weather extremes like the western U.S. drought are becoming much more common as so-called “blocking patterns” in which hot or wet weather lingers over a region are happening twice as often over the past decade.  The blocking patterns occur when the normal meandering of the jet stream slows down.

“Since 2000 we have seen a cluster of these events,” Dr. Dim Coumou of the Potsdam Institute for Climate Impact Research told the Guardian.  “When these high altitude waves become quasi-stationary, then we see more extreme weather at the surface.  It is especially noticeable for heat extremes.”

On Top of Withering Drought, California Smashes Heat Records

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