World View of Global Warming

For details on how to lease this exhibit, see below and contact Gary Braasch, info@worldviewofglobalwarming.org or Jo Krinn, jkrinn@nrdc.org

In the Arctic, even warmer.

Scientists have been estimating past temperatures from cores in the Greenland ice cap, pollen layers in ancient lakes, and tree ring coring. These records indicate that the current temperature is the highest it has been in 400 years. As in Antarctica, the greatest temperature changes occur during the winter months, which are as much as 6° C warmer than they were 30 years ago.

Relying in part on recently declassified nuclear submarine sonar measurements of the Arctic Ocean permanent sea ice, scientists believe that since 1974 it has thinned from 9 feet to 6 feet and shrunk in area by 14 percent. Overflight radar and laser measurements by NASA also found that many of Greenland's outlet glaciers are thinning and discharging into the Atlantic Ocean more rapidly. These changes may influence annual weather cycles and an interconnected set of deep ocean "conveyors" that drive the Gulf Stream and other currents.

A rise in Arctic temperatures may sound like good news for some farmers and residents of northern latitudes, but overall its effects are ominous. Forest fires and insect attacks are plaguing the boreal forests that ring the Arctic, cover 11 percent of the planet's surface and comprise one third of the world's forests. At the same time, the boreal forest and its associated shrub population are starting to migrate north, overtaking the native tundra. Glaciers in Alaska and elsewhere are shrinking, and at the same time snowfall over much of the Arctic is increasing. Permafrost is freezing less often in winter and thus thawing more deeply in summer, damaging forests and manmade structures and allowing rivers to erode vast areas along the Arctic Ocean shore.

These drastic changes are affecting native species - and the people who call the Arctic their home. Polar bears cannot reach their denning spots or their prey. Caribou's habitual feeding locations are changing. Researchers can now measure changed and earlier growth of tundra plants. Native Alaskans have reported adverse shifts in ice and in the permafrost underlying their communities. Perhaps most threatening, dying forests and thawing permafrost are beginning to pump a huge flux of carbon dioxide into the atmosphere in a region that once served as a carbon absorber. This feedback loop could combine with increased open Arctic Ocean waters to escalate the rate of change.

Article © 2001 Gary Braasch (based in part on an information sheet by Gary Braasch and Dr. Daniel Lashof of NRDC. Dr. Lashof bears no responsibility for errors in this version.)

For sources of information for this article, please see the References for World View of Global Warming.

Photographs from the World View of Global Warming are available for license to publications needing science photography, environmental groups and agencies, and other uses. Stock photography and assignments available.

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