Open Water And Thin Ice In The Arctic
August 29, 2000
Open water at the top of the world isn't evidence that the North Pole is melting, as a recent New York Times article suggested. The hole is probably just a temporary opening in the ice pack, polar scientists say.
- Holes in the ice can close after days or persist all season, said Drew Rothrock, a polar-ice expert at the University of Washington in Seattle.
- In the Arctic, "it's not uncommon to have 10 percent open water in the summertime," added James Morison, also of the University of Washington.
- Winds and physical stress can easily fracture the Arctic pack ice, which floats in a frozen mass and is not anchored to a continent as the Antarctic ice sheet is.
Still, the ice pack has been steadily shrinking and growing thinner over decades. Records compiled by Navy submarines reveal the average end-of-summer ice thickness has slimmed from about 10 feet to 6 feet since 1958, according to data Rothrock and colleagues published recently in Geophysical Research Letters.
- Satellite measurements show that the Arctic ice pack has been shrinking by about 3 percent per decade since 1978.
- A team of Norwegian scientists recently reported in Science that multiyear ice -- which remains after the summer melt and is, on average, about three times thicker than seasonal ice -- is decreasing at a rate of 7 percent per decade.
But it's a stretch to tie any specific hole in the ice to climate change, said Mark Serreze, of the National Snow and Ice Data Center at the University of Colorado.Source: Alexandra Witze, "New North Pole assertion may rest on thin ice; Reports of open waters in Arctic don't enhance warming evidence," Dallas Morning News, August 28, 2000.
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