REVIEW & OUTLOOK
Not So HotAugust 29, 2007;PageA14
The latest twist in the global warming saga is the revision in data at NASA's Goddard Institute for Space Studies, indicating that the warmest year on record for the U.S. was not 1998, but rather 1934 (by 0.02 of a degree Celsius).
Canadian and amateur climate researcher Stephen McIntyre discovered that NASA made a technical error in standardizing the weather air temperature data post-2000. These temperature mistakes were only for the U.S.; their net effect was to lower the average temperature reading from 2000-2006 by 0.15C.
The new data undermine another frightful talking point from environmentalists, which is that six of the 10 hottest years on record have occurred since 1990. Wrong. NASA now says six of the 10 warmest years were in the 1930s and 1940s, and that was before the bulk of industrial CO2 emissions were released into the atmosphere.
Those are the new facts. What's hard to know is how much, if any, significance to read into them. NASA officials say the revisions are insignificant and should not be "used by [global warming] critics to muddy the debate." NASA scientist Gavin Schmidt notes that, despite the revisions, the period 2002-2006 is still warmer for the U.S. than 1930-1934, and both periods are slightly cooler than 1998-2002.
Still, environmentalists have been making great hay by claiming that recent years, such as 1998, then 2006, were the "warmest" on record. It's also not clear that the 0.15 degree temperature revision is as trivial as NASA insists. Total U.S. warming since 1920 has been about 0.21 degrees Celsius. This means that a 0.15 error for recent years is more than two-thirds the observed temperature increase for the period of warming. NASA counters that most of the measured planetary warming in recent decades has occurred outside the U.S. and that the agency's recent error would have a tiny impact (1/1000th of a degree) on global warming.
If nothing else, the snafu calls into question how much faith to put in climate change models. In the 1990s, virtually all climate models predicted warming from 2000-2010, but the new data confirm that so far there has been no warming trend in this decade for the U.S. Whoops. These simulation models are the basis for many of the forecasts of catastrophic warming by the end of the century that Al Gore and the media repeat time and again. We may soon be basing multi-trillion dollar policy decisions on computer models whose accuracy we already know to be less than stellar.
What's more disturbing is what this incident tells us about the scientific double standard in the global warming debate. If this kind of error were made by climatologists who dare to challenge climate-change orthodoxy, the media and environmentalists would accuse them of manipulating data to distort scientific truth. NASA's blunder only became a news story after Internet bloggers played whistleblower by circulating the new data across the Web.
So far this year NASA has issued at least five press releases that could be described as alarming on the pace of climate change. But the correction of its overestimate of global warming was merely posted on the agency's Web site. James Hansen, NASA's ubiquitous climate scientist and a man who has charged that the Bush Administration is censoring him on global warming, has been unapologetic about NASA's screw up. He claims that global warming skeptics -- "court jesters," he calls them -- are exploiting this incident to "confuse the public about the status of knowledge of global climate change, thus delaying effective action to mitigate climate change."
So let's get this straight: Mr. Hansen's agency makes a mistake in a way that exaggerates the extent of warming, and this is all part of a conspiracy by "skeptics"? It's a wonder there aren't more of them.