July 20, 2007 — Contrary to common belief, melting glaciers due to global warming contribute more to the rising sea level than the Antarctic and Greenland ice sheets, researchers said Thursday in a study.
Scientists found that the ebb and flow of glaciers where they meet the water causes them to speed up and deliver more ice into the world's oceans than previously estimated, said the study published in Science's latest issue.
Glaciers and ice caps account for 60 percent of the meltwater that flows into the oceans, which has been speeding up over the past 10 years from global warming, said the study's chief author, emeritus professor Mark Meier of University of Colorado's Boulder's Institute of Arctic and Alpine Research.
Together, glaciers and ice caps drop into the oceans 100 cubic miles of ice each year, equal to the volume of Lake Erie, one of the five Great Lakes of the United States.
And the volume of ice grows by three cubic miles each year.
By comparison, the study said, ice breaking off and melting from Greenland's ice sheet contributes 28 percent of the world's ice to the oceans, and the Antarctic ice sheet another 12 percent.
The accelerating contribution of glaciers and ice caps is due in part to rapid changes in the flow of tidewater glaciers that discharge icebergs directly into the ocean, the researchers said.
When the glacier with its "toe in the water" thins, they said, a larger fraction of its weight is supported by water and it slides faster and sends more ice into the ocean.
