Bob Tippee
Watch what happens now—and what doesn't.
A pioneer of global-warming precaution has produced what he calls a "smoking gun" pointing to climate change of human origin.
The pioneer is James Hansen of NASA's Goddard Institute of Space Studies, whose 1988 testimony to a Senate committee energized the politics of global warming.
Amid a controversy that makes science difficult to distinguish from politics, Hansen deserves special attention. He has been and remains an advocate of policies to cut emissions of greenhouse gases. But in 1998 he put science before politics by reporting new appreciation for uncertainty in climate behavior.
His smoking gun is validation by ocean measurements of a model showing that the planet absorbs more energy than it emits into space. He says the measurements confirm that climate effects lag behind causes, such as increases in concentrations of greenhouse gases. Hansen and his colleagues predict the climate would warm by a further half-degree Celsius even if greenhouse gases stabilized.
The findings appeared Apr. 28 in Science Magazine and were duly reported by the general media. A headline in the New York Times: "Experts: New Data Show Global Warming."
Of course, warming is no longer in question. Still at issue are the extent to which human activity causes warming, the likely extent of future warming, and the likely effectiveness of human precautions against perceived warming threats.
The new Hansen findings provoked a response from Patrick Michaels, research professor of environmental sciences at the University of Virginia.
Michaels, a long-time opponent of Hansen's views, said that in his new report the NASA scientist cut the surface-temperature change assumed to result for each additional unit of energy reradiated by changes in the greenhouse effect.
In an Apr. 29 column on the Tech Central Station web site (www.techcentralstation.com), Michaels wrote, "You would think that it would be big news when Hansen—the guy who started all this mess with his incendiary 1988 congressional testimony—lowers his estimate for [climate] sensitivity to two thirds of the value he used back then."
So far, that part of the story hasn't made the news. Tomorrow, perhaps.
(Online Apr. 29, 2005; author's e-mail: [email protected])