Melting ice threatens sea level rise

WASHINGTON - The Earth is already shaking beneath melting ice as rising temperatures threaten to shrink polar glaciers and raise sea levels around the world.

By the end of this century, Arctic readings could rise to levels not seen in 130,000 years — when the oceans were several feet higher than now, according to new research appearing in Friday's issue of the journal Science.

Even now, giant glaciers lubricated by melting water have begun causing earthquakes in Greenland as they lurch toward the ocean, other scientists report in the same journal.

In principal findings:

• At the current warming rate, Earth's temperature by 2100 will probably be at least 4 degrees warmer than now, with the Arctic at least as warm as it was 130,000 years ago, reports a research group led by Jonathan T. Overpeck of the University of Arizona.

• Computer models indicate that warming could raise the average temperature in parts of Greenland above freezing for multiple months and could have a substantial impact on melting of the polar ice sheets, says a second paper by researchers led by Bette Otto-Bliesner of the National Center for Atmospheric Research. Melting could raise sea level one to three feet over the next 100 to 150 years, she said.