Global warming skeptics use cold weather as evidence.

Articles — By forcechange on March 4, 2008 2:30 am

The New York Times had an interesting article by journalist and blogger Andrew Revkin about the tendency of some people to view discrete weather events as evidence of the truth behind their position on global warming. Revkin notes that this past year has been much colder than those in recent times and is being used by skeptics as evidence that global warming is not occurring.

One example he gives is the press release from the communications director for the Republican minority on the Senate Environment and Public Works Committee, which reads: “Earth’s ‘Fever’ Breaks: Global COOLING Currently Under Way.”

Most climatologists believe that the recent cold spell is likely related to the common weather phenomenon, La Niña (a chilling in the tropical Pacific), but could also be affected by sunspot cycles or other common shifts in oceanic or atmospheric patterns. Additionally, there have been similar instances when temperatures have dropped in the short term only to return to the long term warming trend (including 1988, 1991-92 and 1998).

Of course arguments based on short term discrete events should be treated with much less credibility than long term comprehensive trends. There is a reason why “anecdotal evidence” is a catch-phrase for evidence that is easy to use but of little scientific value. Unfortunately for those involved in the efforts to reduce greenhouse gas emissions, often members of that movement are guilty of the same offense.

Specifically, one of our major criticisms of Al Gore’s An Inconvenient Truth was the fact that he used events like Hurricane Katrina as evidence of global warming. While it is possible that Katrina was related to climate change, by using anecdotal evidence as part of his overall argument, he invited rebuttal by this same type of event based evidence. (Which was probably unnecessary for his film given his extensive presentation of long term scientific evidence, as well.)

If this debate is going to continue in the public sphere (in no less a place than the U.S. Senate Environment and Public Works Committee), it is important that the evidence used be reliable and scientifically established in order to ensure credibility.