| Whenever I hear a weather report
declaring it's the hottest June l0 on record or whatever, I can't take it too
seriously, because "ever" really means "as long as the records go back", which
is only as far as the late 1800s. Scientists have other ways of measuring
temperatures before that, though--not for individual dates, but they can ten the
average temperature of a given year by such proxy measurements as growth marks
in corals, deposits in ocean and lake sediments, and cores drilled into glacial
ice. They can even use drawings of glaciers as there were hundreds of years ago
compared with today. And in the most comprehensive compilation of such data to date, says a new report from the National Research Council, it looks pretty certain that the last few decades have been hotter than any comparable period in the last 400 years. That's a blow to those who claim the current warm spell is just part of the natural up and down of average temperatures--a frequent assertion of the global--warming-doubters crowd. The report was triggered by doubts about past-climate claims made last year by climatologist Michael Mann, of the University of Virginia (he's the creator of the "hockey stick" graph A1 Gore used in "An Inconvenient Truth" to dramatize the rise in carbon dioxide in recent years). Mann claimed that the recent warming was unprecedented in the past thousand years--that led Congress to order up an assessment by the prestigious Research Council. Their conclusion was that a thousand years was reasonable, but not overwhelmingly supported by the data. But the past 400 was--so resoundingly that it fully supports the claim that today's temperatures ale unnaturally warm, just as global warming theory has been predicting for a hundred years. And if there's any doubt about whether these proxy measurements are really legitimate, the NRC scientists compared them with actual temperature data from the most recent century, when real thermometers were in widespread use. The match was more or less right on. In the past nearly two decades since TIME first put global warming on the cover, then, the argument against it has gone from "it isn't happening" to "it's happening, but it's natural", to "it's mostly natural"--and now, it seems, that assertion too is going to have to drop away. Indeed. Rep. Sherwood Boehert, the New York Republican who chairs the House Science Committee and who asked for the report declared that it did nothing to support the notion of a controversy over global warming science--a controversy that opponents keep insisting is alive. Whether President Bush will finally take serious action to deal with the warming, however, is a much less settled question. |