The horrific, tragic and enormous tornado in Moore, OK has been described as "the biggest, most destructive tornado in the history of the world."
In its wake, many are questioning the relationship between such monster storms and climate change. Here's a statement from Dr. Kevin Trenberth of the National Center for Atmospheric Research, in response to that question, as obtained via email today by Peter Sinclair (he, of the geat Climate Denial Crock of the Week website):
Of course tornadoes are very much a weather phenomenon. They come from certain thunderstorms, usually super-cell thunderstorms that are in a wind shear environment that promotes rotation. The main climate change connection is via the basic instability of the low level air that creates the convection and thunderstorms in the first place.
Warmer and moister conditions are the key for unstable air.
The climate change effect is probably only a 5 to 10% effect in terms of the instability and subsequent rainfall, but it translates into up to a 32% effect in terms of damage.
(It is highly nonlinear).
So there is a chain of events and climate change mainly affects the first link: the basic buoyancy of the air is increased. Whether that translates into a super-cell storm and one with a tornado is largely chance weather.
So, in short, Trenberth seems to suggest that while one cannot directly "blame" climate change itself for any particular storm, the altered weather patterns, thanks to global warming and the increased moisture in the air, increase, fairly radically, the probability of such storms and, in turn, their size and destructive power.
Or, if you prefer, you can listen to leading climate science denier Republican Sen. James Inhofe of Oklahoma who has said many times in the past that concerns about man-made climate change are nothing more than "the greatest hoax ever perpetrated on the American people" and nothing to worry about.
While we haven't heard him say as much today yet, for some odd reason, he has explained that he --- like his fellow Republican Sen. Tom Coburn, will support federal disaster relief funding for his state, unlike their vote against federal disaster relief funding for the East Coast after Superstorm Sandy last year. Why? Because, as Inhofe explained today, the money for his state won't simply be a "slush fund", as he described the relief for the millions of East Coasters affected by Hurricane Sandy. "That won't happen in Oklahoma," he said.
Meanwhile, Coburn (who is also a climate change denier), after also voting against relief for Hurricane Sandy while tens of thousands were left homeless on the East Coast in the middle of winter, slammed those who charged hypocrisy in his promise of federal relief "without delay" for his own OK constituents.
"It is crass," his office said in a statement to reporters, "for critics to play disaster aid politics when first responders are pulling victims from the rubble."
By Coburn's reckoning, apparently, the time to "play disaster aid politics" is a few days or months later, as he did with Sandy aid, when victims were freezing and without power or homes.