A study funded primarily by the National Science Foundation and NASA has found that melting of glaciers and ice caps will be more of a factor in the rise of sea levels than the huge ice sheets in Greenland and Antarctica. Greenland is accounting for about 28 percent of the total increase and Antarctica is adding around 12 percent. Surpassing this amount are the contributions of the glaciers and ice caps which are responsible for 60 percent of the ice entering the oceans, and the rate has been increasing over the past ten years. At the present time about 100 cubic miles of ice, or almost the volume of water in Lake Erie, is entering the oceans, with an annual increase of three cubic miles. Greenland's contribution won't catch up until the end of the century.

Lead author of the study, Emeritus Professor Mark Meier of CU-Boulder's Institute of Arctic and Alpine Research said, "One reason for this study is the widely held view that the Greenland and Antarctic ice sheets will be the principal cause of sea-level rise. But we show that it is th glaciers and ice caps, not the two large ice sheets, that will be the big players in sea rise for at least the next few generations."

The study found that the increasing effect of glacier and ice cap melting is in part caused by changes in tidewater glaciers, which result in icebergs entering directly into the sea. The glaciers move more rapidly as a consequence of rapid thinning and other changes, resulting in more ice being discharged into the ocean. When a glacier thins, water beneath the ice enables the glacier to move more rapidly toward the ocean.

An example given in the study is the Columbia Glacier in Alaska, which currently releases around two cubic miles of ice each year into Prince William sound. Having thinned up to 1,300 feet in some areas, the glacier has shrunk about nine miles since 1980 and could possible shrink another nine miles over the next twenty years.

If the estimates of researchers are accurate, sea levels will increase from 4 to 9.5 inches by the end of the century due to the melting of glaciers and ice caps, and expansion of sea water as a result of warming could double that amount. For every rise in sea levels of one foot, the shoreline will usually recede about 100 feet. Currently about 100 million people live within three feet of sea level.

Information used in the study was obtained by satellite, aircraft, and ground-based systems from the glaciers and ice caps as well as the West Antarctic ice sheet, the East Antarctic ice sheet, and the Greenland ice sheet.

Learn more about this author, Nancy L. Young-Houser.
Click here to send author comments or questions.

---

Add your voice

Know something about Global warming: Is it as bad as it's made out to be??
We want to hear your view. Write now!