NCPA - National Center for Policy Analysis

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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