How To Beat The Heat

Warmth that's good for crops is also good for crop pests. A longer growing season could, for example, enable grasshoppers to squeeze in another round of reproduction. Weeds and crop diseases will also thrive in a warmer world where fewer regions experience the harsh winters that keep pest populations in check. ""All indications are that pests, and diseases like rusts and molds, will increase,'' says Linda Mearns of NCAR. In the United States and other affluent countries, farmers will likely adapt. They will irrigate more, fertilize more and apply pesticides more. But adaptation is expensive, and can go only so far. ""The climate is going to be in continual change,'' says NCAR's Trenberth. ""I'm not sure people realize this. Inability to plan [for stable weather patterns] may be worse than the changes themselves.''

Living things that don't have farmers looking out for them may meet with a more dire fate. Kirtland's warbler, an endangered bird that nests exclusively under young jack pines in northern Michigan, faces a grim future: with more heat and less rain, jack pines there will likely die off in the next 30 to 90 years. So, therefore, may the warbler. Populations of Adelie penguins in the Antarctic Peninsula have fallen 40 percent in 22 years; midwinter mercury readings around the AdElie's home are up a huge 8 or 9 degrees in the last 50 years, melting the sea ice where the Adelie's food--shrimplike krill--lives. Bird lovers' greatest concern is the 1 million-plus sandpipers, red knots, ruddy turnstones and other birds that make a fuel stop at Delaware Bay during their spring migration to the Arctic. The birds' stop coincides with the emergence of horseshoe crabs, triggered by the full moon, from the ocean. The birds eat the newly laid crab eggs. But if the birds take wing from their wintering grounds earlier, because spring arrives earlier, then they will pass over the Delaware before the crabs emerge. In that case they would miss the caviar banquet, and be too low on fuel to reach the Arctic.

Things will get really interesting if the changes global warming brings are not incremental but sudden. One place vulnerable to abrupt change is the Atlantic Ocean current that brings warm water from the Sargasso Sea to Britain. The driving force behind the current is salty water that sinks when it gets cold, at its northern terminus. Like a grocery-store conveyor belt, the sinking of one end draws the rest of the belt forward--in this case, northward. But if the oceans warm enough, the water will not sink. The current would shut down, explains Wallace Broecker of Columbia University, with ""consequences [that] could be devastating.'' Dublin would have the climate of Spitsbergen, Norway, as the collapse of the current makes temperatures in Western Europe plunge 20 degrees in 10 years. Loser: European agriculture.

It shouldn't be surprising that climate change will produce some winners. After all, roofers in south Florida cleaned up after Hurricane Andrew, as do construction crews in California after earthquakes. But climate change will almost surely bring more losers than winners. Some losers will be able to buy a reprieve--New England ski-resort owners, faced with a shorter season, can dump man-made snow on their slopes, and governments can take steps to control tropical diseases, whose spread depends as much on public-health measures as on where pests can live. But such adaptations are expensive. And you can't write a check to bring back melted glaciers. The debate in Kyoto will focus on how much it will cost the world's economies to burn less coal, oil and gas. Now scientists are coming to understand who will lose if we don't.

In the poll, 11% say global warming would be 'disastrous' for today's adults while 29% say it would be that bad for today's children when they're grown.

63% of respondents say the greenhouse effect can be reduced in ways that will not hurt the economy; 24% say such steps would hurt the nation's bottom line.