According to the Arctic Climate Impact Assessment, released Monday (11-8-2004), average temperatures in Alaska, western Canada, and eastern Russia have increased as much as 4 to 7 degrees Fahrenheit (3 to 4 degrees Celsius) in the past 50 years, nearly twice the global average. The study projects that temperatures will rise 7 to 13 degrees Fahrenheit (4 to 7 degrees Celsius) over the next hundred years. The rising temperatures are likely to cause the melting of at least half (and possibly all) the Arctic sea ice by the end of the century. A significant portion of the Greenland ice sheet — which contains enough water to raise the worldwide sea level by about 23 feet (about 7 meters) — would also melt.
The four-year study of the Arctic climate involved an international team of more than 300 scientists. They used a number of climate models and made a "moderate estimate" of future emissions of carbon dioxide and other greenhouse gases that are widely believed to be contributing to the recent warming trend of the Earth's climate.
"The impacts of global warming are affecting people now in the Arctic," said Robert Corell, chairperson of the Arctic Climate Impact Assessment, in a news release. "The Arctic is experiencing some of the most rapid and severe climate change on Earth. The impacts of climate change on the region and the globe are projected to increase substantially in the years to come."
"Everything is under threat," said Chief Gary Harrison of the Arctic Athabaskan Council. "Our homes are threatened by storms and melting permafrost, our livelihoods are threatened by changes to the plants and animals we harvest. Even our lives are threatened, as traditional travel routes become dangerous."
However, the biggest danger, many experts warn, is that global warming will cause sea levels to rise dramatically; as water warms its volume increases. Thermal expansion has already raised the oceans 4 to 8 inches (10 to 20 centimeters). "The consequences would be catastrophic," said Jonathan Overpeck, director of the Institute for the Study of Planet Earth at the University of Arizona in Tucson. "Even with a small sea level rise, we're going to destroy whole nations and their cultures that have existed for thousands of years."
Overpeck and his colleagues have used computer models to create a series of maps that show how susceptible coastal cities and island countries are to the sea rising at different levels. The maps show that a 1-meter (3-foot) rise would swamp cities all along the U.S. eastern seaboard. A 6-meter (20-foot) sea level rise would submerge a large part of Florida.
"The impacts of global warming are affecting people now in the Arctic," said Corell. "The Arctic is experiencing some of the most rapid and severe climate change on Earth. The impacts of climate change on the region and the globe are projected to increase substantially in the years to come."