Dessler vs. Rick Perry: Is the 2011 Texas Drought Evidence of Human-Caused Climate Change?

September 5th, 2011 by Roy W. Spencer, Ph. D.

One of the most annoying things about the climate change debate is that any regional weather event is blamed on humans, if even only partly. Such unscientific claims cannot be supported by data — they are little more than ambiguous statements of faith.

The current “exceptional” Texas drought is no exception. People seem to have short memories…especially if they were born after most of the major climate events of the past occurred.

Andy Dessler recently made what I’m sure he thought was a safe claim when faulting Texas Gov. Rick Perry for being “cavalier about climate change” (as if we could stop climate from changing by being concerned about it).

Dessler said, “..warming has almost certainly made the (Texas) heat wave and drought more extreme than it would otherwise have been.”

This clever tactic of claiming near-certainty of at least SOME effect of humans on weather events was originally invented by NASA’s James Hansen in his 1988 Senate testimony for Al Gore, an event that became the turning point for raising public awareness of “global warming” (oops, I’m sorry, I mean climate change).

The trouble is that climate change theory predicts changes, up and down, in just about anything you can imagine. So, anything unusual that happens anywhere, anytime, is deemed “consistent” with global warming.

But this tactic can work both ways — a specific drought might have instead been made LESS severe by the general tendency toward MORE rainfall, which is a much more robust prediction of the climate models with warming.

For example, let’s look at June-July total rainfall over the whole contiguous U.S. — which is only 1.6% of the Earth’s surface — over the last 100+ years (August data are not yet posted at NCDC):

To read the rest (including some great chart porn) go here.

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