Sunday, November 20, 2005
TOOLIK LAKE, Alaska - Bruce Peterson, on his hands and knees, claws through a thick pad of peat moss and into the brown muck beneath. "Put your hand in there and feel that," he says over his shoulder.
The hole is an icebox chilled by a slab of frozen soil that starts about a foot below the surface and, in places, extends deeper than the length of a football field.
The permafrost on Alaska's northern reaches froze thousands of years ago and has acted as a year-round thermostat for the tundra's plants, animals and water systems.
But in recent decades, temperatures have warmed in the Arctic, and the top layers of the permafrost have thawed. One longtime researcher predicts that half of interior Alaska's permafrost could be gone by the end of the century.
In some places, the tundra is already crumbling into itself because of the thawing. In other places, suddenly unstable trees are tilting over in "drunken forests" and coastal villages on eroding land are being relocated.
They are just a few tangible signs of the Earth's warming, scientists say.
"We think the system is falling apart," says Peterson, a scientist who has been tracking the effects of climate change in Alaska since 1976. "This is the canary in the mine. There's no other latitude on Earth that's seen that kind of change."
In the Arctic, climate change - in the form of melting sea ice, shifting vegetation and thawing permafrost - is arriving sooner and more intensely than anywhere else on the planet, scientists say.
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