Alaska landscape transformed by warmer climate

By Yereth Rosen
28 Sep 2005 20:33:13 GMT

ANCHORAGE, Alaska, Sept 28 (Reuters) - Sinking villages perched on thawing permafrost, an explosion of timber-chewing insect populations, record wildfires and shrinking sea ice are among the most obvious and jarring signs that Alaska is getting warmer as the global climate changes, scientists say.

"We are the canary in the mine, unfortunately, and the harbinger of what is yet to come for the rest of the world," said Patricia Cochran, executive director of the Anchorage-based Alaska Native Science Commission.

Atmospheric temperatures in the remote state have risen 3.6 to 5.4 degrees Fahrenheit (2 to 3 degrees C) over the past five decades, according to the recently released Arctic Climate Impact Assessment, a comprehensive study by scientists from eight nations.

That heating, most pronounced in winter and spring, is much more dramatic than in the rest of the world, which has had an average increase in land surface temperatures of 1 degree F (0.6 C) over the last century, according to the Environmental Protection Agency.

Many scientists believe the earth is warming because of the release of greenhouse gases such as carbon dioxide that trap solar heat in the atmosphere.

A massive beetle infestation has swept through millions of acres (hectares) in south-central Alaska over the past decade, scientists said, because significantly warmer weather is delaying the usual winter die-off of insect populations.

The insects' voracious attack on spruce bark has left forests tinder-dry while general heat-induced stress have weakened forests, with lightning strikes making them a fire hazard in the Chugach Mountain foothills, said Glenn Juday, a professor of forest ecology at the University of Alaska Fairbanks.

"All the trees in the boreal forest are showing unusual symptoms of warmth-related health problems," Juday said, noting that Alaska had its biggest and third-biggest fire seasons in the past two summers.
"The warmer it gets the more we burn," Juday said.

In the cooler interior regions, buildings are slumping and roads are buckling as permafrost -- frozen soil -- thaws and turns into softer, spongy soil. The Inupiat village of Shishmaref on a narrow Chukchi Sea barrier island is preparing to move as the town sinks into the ground.

"For those of us who live in the changing conditions every day, there's no question. We see it. We feel it every single day," Cochran said.

Satellite records released on Wednesday showed that sea ice coverage in the arctic region has fallen for the last four years with "unusually early springtime melting in areas north of Siberia and Alaska," according to a study by the University of Colorado, NASA and the University of Washington.

Shrinking sea ice has created hardships for sea animals like polar bears that find their prey at the ice's edge.

Heated-up waterways are throwing off long-established salmon cycles and, according to one scientist, have allowed a warmth-loving, salmon-wrecking parasite to thrive in the Yukon River.

Warming is accentuated in high-latitude regions like Alaska in part because of thinner atmospheres in the polar region, concentrating greenhouse gases, and in part because of the nature of atmospheric currents, according to studies.

Such changes have also contributed to falling ice coverage in the Arctic Sea, with spring and summer melting happening 17 days earlier than usual, according to the satellite study.

The disappearance of ice and snow uncovers dark surfaces of the ground and sea, which absorb more solar heat and warm up the landscape, said Vladimir Romanovsky, a permafrost expert at the University of Alaska Fairbanks' Geophysical Institute.