|
|||
1. Roast, or idle boast?
On average, 832,000 acres burn annually in U.S. national forests, but 2002 is proving to be one of the hottest years ever. USDA.
|
|
Truly
warming?
In climatology, such a hypothesis might say, "Given the current rate of increase in greenhouse gases, what global average temperature can we expect in 50 years?" An even better understanding might come from a controlled experiment: "Let's hold other greenhouse gases constant but double carbon dioxide, to see how carbon dioxide influences warming by itself." These are great experiments, but you simply can't do them as you would do, say, an experiment in particle physics. If you think of climate predictions as hypotheses, the only way to test them is to watch climate behave through the years. "If you want to wait 100 years, I can tell you for sure" whether global warming is a fact, says Jonathan Foley, an environmental scientist at University of Wisconsin-Madison. "But by the time we have perfect evidence, global warming will be so severe that it will be impossible to undo." Twice as nice with dice! And loading the climate dice is exactly what we are doing as we pump billions of tons of greenhouse gases into the atmosphere each year, Schneider says. Because it's impossible to do the experiments, it's impossible to know if the torrid pace of warming in recent years really signifies rapid warming. "Twenty years is not a long time," says Schneider, "and we don't have a pair of climate dice to roll 1,000 times to figure out if this is an accident."
Schneider, however, is convinced that human actions are the best explanation for the current heat-up. "I'd argue that global warming at the surface is a virtual fact. At a very high probability, way above 90 percent." Still, he's willing to admit that he could be wrong. "Most people in climate science would argue that we are loading the dice, but to know for sure, you would have to run the experiment." Can't compute Bad data will produce errors (and don't forget that acquiring data is a big problem in climate studies). And no matter how much models are refined, it's not possible, even in theory, to include every relevant factor. Sure, aerosols were factored in after Mt. Pinatubo, but how, for example, would we get data on these critical scientific, political and economic questions:
Must compute
While climatologists argue the fine points, he asks, "Where is there a reasonable doubt about global warming? Every piece of evidence says the world is getting warmer and CO2 is rising. Every law of physics says that increasing CO2 will trap heat. We don't have 100 percent statistical proof, but we've got a smoking gun, a motive and a body. What else does a regular person need to make a decision?" In law and medicine, decisions are routinely made without perfect evidence, Foley continues. "Scientists have the luxury of living in an ivory tower, of not making decisions. We have to stay honest to the science, but we also need to recognize that regular people need to move forward without perfect data." So what should we do now?
|
|
|
![]() ![]() |
||
![]() |
There are 1 2
3 4 5 pages
in this feature. ©2002, University of Wisconsin, Board of Regents. |