"Some glaciers around the world now are smaller than they have been in the last several thousand years," said Mark Meier, emeritus professor and former director of Colorado University's Institute for Arctic and Alpine Research, Boulder.
However, Meier told United Press International that the world will not have to wait 100 years to see the effects of rising sea levels as some problems are already emerging. "We are already seeing loss of property and property damage along the East Coast due in part to rising sea levels," he said.
Particularly at risk are low-lying cities such as Houston and New Orleans, said Meier. Also of concern are island nation-states such as Kiribati -- consisting of a series of atolls -- in the Pacific Ocean and the Seychelles in the Indian Ocean. He said a rise of sea level of about 3 feet could put half the nation of Bangladesh under water, displacing 100 million people.
"The increase in glacier melt, however, is only half the story," Meier said during the annual meeting of the American Association for the Advancement of Science in Boston.
As global warming continues and oceans become warmer, the oceans will rise simply due to the fact that warm water expands and takes up more space, he said. "That could double the estimate of how much the oceans could rise," he suggested.
The shore gradually slopes toward the ocean with a drop of one foot every 100 feet, Meier explained. So a 1-foot rise in sea level would put 100 feet of shoreline underwater. He said, however, that thousands of feet of shoreline in river estuary systems could be at risk from rising sea levels.
Meier noted that his predictions exceed those of the International Panel on Climate Control in 2001. He said the panel may have underestimated the worldwide glacier melt due to the lack of information about some of the world's largest glacial formations such as those in Alaska. The IPCC calculation for the 21st century was a rise of about 2 inches to 5 inches. Meier calculated that glacier melting could contribute 7 inches to 11 inches to sea level this century.
Until recently, these glaciers, due to their extreme size and remoteness could not be accurately measured. Meier said researchers using laser-assisted measuring devices and Global Positioning System technology to monitor the height of a airplane were able to precisely show that some of these Alaskan glaciers had lost two to three feet of depth over the past decade.
Other researchers said indicators of global warming also appear in studies of huge Antarctic ice shelves and in polar temperatures. "Ice shelves that have been stable for centuries are being lost over a spectacularly short period of time," said Ted Scambos, a glaciologist at the National Snow and Ice Data Center, part of the Cooperative Institute for Research in the Environmental Sciences, based at the University of Colorado.
In the same press briefing in which Meier and Scambos discussed their findings, Mark Serreze, a climatologist at the center, said arctic temperatures have been the warmest in centuries. "We are seeing significant surface air temperature increases over the Arctic Ocean," he said, "accompanied not only by an 18-year downturn in ice cover over the Atlantic Ocean but by a record reduction in ice cover" in other arctic seas.