Arctic Meltdown

Scientists have assembled some hard, not-so-cold facts about climate change in the Arctic.

Over the past 100 years, things have been heating up in the Arctic, as evidenced by a long list of startling statistics: Arctic air temperatures are higher than they have been in four centuries, Alaskan glaciers are retreating at unprecedented rates, the sea-ice cover has lost up to 40% of its thickness, permafrost has started to thaw, and the snow-free season has lengthened by several days each decade since the 1970's.

To cope with this constellation of changes, several federal agencies have begun to coordinate their Arctic studies in a program called SEARCH (Study of Environmental Arctic Change.) Their research will shed light on not just the Arctic, but the entire planet, since the polar regions control the earth's heat balance. As long as the highly reflective ice cover in the Arctic is in tact, it will continue to send sunlight back into space, keeping the Arctic cool. But as it begins to melt and shrink, less light will be reflected, and global temperatures will begin to rise.

Since each change in the Arctic climate sets off a complex chain of reactions, predicting the future state of the region is a challenge. For instance, about 600 cubic miles of carbon are currently trapped in cold storage under the Arctic Tundra. As temperatures rise, the tundra is beginning to release carbon dioxide, which works like an insulator to trap the sun's heat. However, warmer temperatures may also mean more plant growth, which could provide a new way for the tundra to take in carbon dioxide.

McCall Glacier has lost nearly 33 feet in depth over the past four decades. It is one of the most extensively studied glaciers in the circumpolar north for signs of climate change due to global warming. Photo: Suhankar Banerjee

These are several of the small, unnamed, retreating glaciers and recently deglacierized cirques and ridges in Alaska's Chugach Mountains. Much of the ice disappeared during the last few decades of the twentieth century. Note the fresh moraine deposits and the tarn lakes.
Photograph by Bruce F. Molnia, USGS.

Moose did not inhabit the North Slope of the Arctic Refuge until the 1940s and 50s, when gradual warming allowed dwarf willows, their main food source during winter months, to grow there. Photo: Suhankar Banerjee
Elevated ocean surface temperatures due to warming trends in recent years have led to increased evaporation and deeper than usual snow on the coastal plain, making foraging difficult for both muskox and caribou.
Photo: Suhankar Banerjee