1. Why are global warming specialists watching the Arctic so closely?

The Arctic is global warming's canary in the coal mine. It's a highly sensitive region, and it's being profoundly affected by the changing climate. Most scientists view what's happening now in the Arctic as a harbinger of things to come.

[pic] ince 1979, the size of the summer polar ice cap has shrunk more than 20 percent. (Illustration from NASA)

2. What kinds of changes are taking place in the Arctic now?

Average temperatures in the Arctic region are rising twice as fast as they are elsewhere in the world. Arctic ice is getting thinner, melting and rupturing. For example, the largest single block of ice in the Arctic, the Ward Hunt Ice Shelf, had been around for 3,000 years before it started cracking in 2000. Within two years it had split all the way through and is now breaking into pieces.

The polar ice cap as a whole is shrinking. Images from NASA satellites show that the area of permanent ice cover is contracting at a rate of 9 percent each decade. If this trend continues, summers in the Arctic could become ice-free by the end of the century.

3. How does this dramatic ice melt affect the Arctic?

The melting of once-permanent ice is already affecting native people, wildlife and plants. When the Ward Hunt Ice Shelf splintered, the rare freshwater lake it enclosed, along with its unique ecosystem, drained into the ocean. Polar bears, whales, walrus and seals are changing their feeding and migration patterns, making it harder for native people to hunt them. And along Arctic coastlines, entire villages will be uprooted because they're in danger of being swamped. The native people of the Arctic view global warming as a threat to their cultural identity and their very survival.

4. Will Arctic ice melt have any effects beyond the polar region?

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ALASKA HEATS UP
The effects of global warming on the north are not limited to the Arctic -- higher temperatures are already affecting people, wildlife and landscapes across Alaska. Click on the numbers on this map to see what's happening on the front lines of global warming.
1. Barrow 2. Shismaref 3. Yukon River 4. Wasilla 5. Kenai Peninsula 6. McCall Glacier 7. Fairbanks

[pic](See more Google Earth maps.)

Yes -- the contraction of the Arctic ice cap is accelerating global warming. Snow and ice usually form a protective, cooling layer over the Arctic. When that covering melts, the earth absorbs more sunlight and gets hotter. And the latest scientific data confirm the far-reaching effects of climbing global temperatures.

Rising temperatures are already affecting Alaska, where the spruce bark beetle is breeding faster in the warmer weather. These pests now sneak in an extra generation each year. From 1993 to 2003, they chewed up 3.4 million acres of Alaskan forest.

Melting glaciers and land-based ice sheets also contribute to rising sea levels, threatening low-lying areas around the globe with beach erosion, coastal flooding, and contamination of freshwater supplies. (Sea level is not affected when floating sea ice melts.) At particular risk are island nations like the Maldives; over half of that nation's populated islands lie less than 6 feet above sea level. Even major cities like Shanghai and Lagos would face similar problems, as they also lie just six feet above present water levels.

Rising seas would severely impact the