National Geographic : 2004 Sep
SIGNS FROM EAR TH 0 0 M Global warming can seem too remote to worry about, or too * uncertain-something projected by the same computer techniques that often can't get next week's weather right. On a raw winter day you might think that a few degrees of warming wouldn't be such a bad thing anyway. And no doubt about it: Warnings about climate change can sound like an environmentalist scare tactic, meant to force us out of our cars and cramp our lifestyles. Comforting thoughts, perhaps. But turn to "GeoSigns," the first chapter in our report on the changing planet. The Earth has some unsettling news. From Alaska to the snowy peaks of the Andes the world is heating up right now, and fast. Globally, the temperature is up 1°F over the past century, but some of the coldest, most remote spots have warmed much more. The results aren't pretty. Ice is melting, rivers are running dry, and coasts are erod ing, threatening communities. Flora and fauna are feeling the heat too, as you'll read in "EcoSigns." These aren't projections; they are facts on the ground. The changes are happening largely out of sight. But they shouldn't be out of mind, because they are omens of what's in store for the rest of the planet. Wait a minute, some doubters say. Climate is notoriously fickle. A thou sand years ago Europe was balmy and wine grapes grew in England; by 400 years ago the climate had turned chilly and the Thames froze repeatedly. Maybe the current warming is another natural vagary, just a passing thing? Don't bet on it, say climate experts. Sure, the natural rhythms of climate might explain a few of the warming signs you'll read about in the following pages. But something else is driving the planet-wide fever. For centuries we've been clearing forests and burning coal, oil, and gas, pouring carbon dioxide and other heat-trapping gases into the atmosphere faster than plants and oceans can soak them up (see "The Case of the Miss ing Carbon," February 2004). The atmosphere's level of carbon dioxide now is higher than it has been for hundreds of thousands of years. "We're now geological agents, capable of affecting the processes that determine climate,"