Hot air

I'm an agnostic when it comes to climate change. I don't pretend to have the scientific understanding to judge the degree to which the Earth is -- or isn't -- warming, whether that change is historically unusual, and whether human beings are likely to play a strong causative role in that change. I am, however, inherently skeptical of doomsday scenarios like those peddled by the worst global-warming scaremongers -- such as Al Gore. So it's with interest that I read this New York Times article that describes the discomfort with which many scientists greet Gore's "An Inconvenient Truth."

Among the important information in the Times article:

Geologists have documented age upon age of climate swings, and some charge Mr. Gore with ignoring such rhythms.

"Nowhere does Mr. Gore tell his audience that all of the phenomena that he describes fall within the natural range of environmental change on our planet," Robert M. Carter, a marine geologist at James Cook University in Australia, said in a September blog. "Nor does he present any evidence that climate during the 20th century departed discernibly from its historical pattern of constant change."

In October, Dr. Easterbrook made similar points at the geological society meeting in Philadelphia. He hotly disputed Mr. Gore's claim that "our civilization has never experienced any environmental shift remotely similar to this" threatened change.

Nonsense, Dr. Easterbrook told the crowded session. He flashed a slide that showed temperature trends for the past 15,000 years. It highlighted 10 large swings, including the medieval warm period. These shifts, he said, were up to "20 times greater than the warming in the past century."

The degree of uncertainty over climate change and its causes represented in this article is important not just as a matter of scientific curiosity, but also because of the vast and potentially expensive policy proposals that have been put forward as solutions to global warming. With responses ranging from the Kyoto Protocol to banning incandescent light bulbs, climate policy threatens to be deeply intrusive and may well have a severe impact on people's standard of living and the details of their everyday lives.

If we're going to hand vast new powers to government officials and give up some of the benefits of modern industrial civilization, we need to know beyond a shadow of a doubt that it's for a good reason -- and that it's better than the alternatives.

Al Gore may make rousing cinema, but he hasn't had the final word in the discussion.