The Weather Notebook: Skating On Thin Artic Ice

Skating On Thin Artic Ice
Listen in RealAudio
Email your weather question

The Melt Season 24 July 98
Photo: SPO, University of Washington
The sheet of ice that covers the Arctic Ocean isn't as massive as you might think. And it's getting smaller. Hi, I'm Dave Thurlow and this is The Weather Notebook.

Unlike the South Pole, which is enveloped by the continent of Antarctica, the North Pole is surrounded by the waters of the Arctic Ocean. Most of this water is covered by an ice pack that deepens in the winter and thins out by about half each summer.

During the cold war, the U.S. sent military submarines underneath the Arctic ice pack. The sailors sent sonar beams upward to measure how thick the ice was. At that time, the average depth of ice was roughly ten feet. In the 1990s, a new series of research cruises covered much of the same areas, as did the military submarines. The new data are disturbing, because they hint that the Arctic is warming--and faster than expected.

The average September ice pack across the Arctic has shrunk from ten feet down to less than six feet. The change is most dramatic in the eastern Arctic, near Russia. There, the average depth has dropped from ten to as little as three feet. The exact cause of this melting isn't known, but it's consistent with the atmospheric warm-up that's been going on since the 1970s.

Many scientists expect global warming to show up most dramatically at the poles. Some computer models project that the Arctic ice pack could disappear completely by the year 2050. But at the rate it's going, much of the ice could pull a summertime disappearing act even sooner, in as little as 20 or 30 years.

Weather Notebook music is composed and performed by Georg Brandl. Funding for the show comes from Subaru and the National Science Foundation.

This image of the Weddell Sea, Antarctica was acquired on October 3, 1994, by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour. This data provides scientists with details about the ice pack they cannot see any other way and is particularly useful in helping scientists estimate the thickness of the ice cover which is often extremely difficult to measure with other remote sensing systems.Jet Propulsion Laboratory,