How To Beat The Heat

Global warming won't be bad for everyone. Some regions and industries will actually benefit. A look at who will win--and who will lose--when we all live in the greenhouse.

AVERAGES DON'T MEAN much to Jacques Couture, 47, whose family has been tapping Vermont's sugar maples ""back to the 1700s, I think,'' he says. Sure, he's been hearing for years how some nasty-sounding thing called the ""global mean temperature'' is expected to rise in the coming decades. Couture figures that will bring nothing more worrisome than a couple more warmer days in August. But means, or averages, can hide great calamities. As the world warms, the climate belts most suitable to particular plants will shift toward the cooler poles. And nights will heat up even more than days will. ""You need the cold nights for good sap flow,'' Couture says. The sugar-maple belt, which now dips into Tennessee, could contract like concrete in the cold, moving farther into Canada. Any trees still south of Maine might not have the cold spring nights needed to make their sap run. On the ledger sheet of global warming's winners and losers, count Couture, or his grandchildren, as potential losers.

Alan Johnson, president of Hudson Bay Port Co. in Churchill, Manitoba, employs 80 dockworkers to load 500,000 tons of grain into container ships. But the men work only from July to October. Before and after, sea ice blocks the bay. The hiatus doesn't do much for the local economy. But global warming might help. The planet, say computer climate models, should heat up the most near the poles. Churchill is about as close to the North Pole as you can get without running into elves. If the world warms, Churchill will be open for business more weeks every year. ""The past few years,'' Johnson said in November, ""the season seems like it's been longer. We still have open water now.'' Put Johnson, and northern ports, in the potential winners' column.

For more than a decade climatologists have been sounding the alarm: the continued release of ""greenhouse gases'' will almost certainly warm the world. Average annual temperatures for the earth's surface are already up 1 degree Fahrenheit in the last 100 years. And the pattern of warming--more in the Arctic than near the equator, more in the night than the day, more in winter than summer--fits that predicted by computer models of man-made climate change better than it does natural climate variability. Such findings spurred the United Nations' Intergovernmental Panel on Climate Change--some 2,500 scientists from academia, environmental groups, industry and government from more than 150 nations--to conclude, in 1996, that man-made warming has already been discerned. Last week the British Meteorological Office announced that November 1996 to November 1997 was the hottest year on record.

And more is on the way. Gases such as carbon dioxide (from deforestation and the burning of coal, oil and natural gas) act like little panes of glass in a greenhouse. With nations pouring at least 7 billion tons of carbon into the atmosphere every year, there is 30 percent more carbon dioxide in the air today than in 1860. (How do scientists know? They analyze pockets of air trapped in ice cores. Then they determine the age of the core by counting layers of ice deposition, much like counting tree rings.) So much warming is built into the atmosphere already that the planet will heat up another half degree in the next 20 years. That's why 160 nations meeting this week in Kyoto, Japan, will try to reach some kind of agreement on what to do about greenhouse emissions. But there's no way to undo the past. ""Even if we are wildly successful in Kyoto,'' says Richard Moss of the IPCC, ""we are in for a doubling of carbon dioxide by the middle of the next century.''

If that happens, we could see the ultimate good news/bad news scenario. Heating bills will go down. That's good. But more people will die of heatstroke, as 465 Chicagoans did during a July 1995 heat wave. That's bad. Longshoremen in northern ports will work more days every year. That's good. But dengue fever, now confined to the tropics, may reach Winnipeg. And rising sea levels will obliterate more than 3,000 square miles of Louisiana coastline and wetlands. Both bad.