Arctic ice thinned dramatically since 2004: NASA
By Deborah Zabarenko, Environment Correspondent WASHINGTON (Reuters) – Arctic sea ice has thinned dramatically since 2004, with the older, thicker ice giving way to a younger, thinner kind that melts in the northern summer, NASA scientists reported on Tuesday. Researchers have known for years that ice covering in the Arctic Sea has been shrinking in area, but new satellite data that measure the thickness of ice show that the volume of sea ice is declining as well. That is important because thicker ice is more resilient and can last from summer to summer. Without ice cover, the Arctic Sea’s dark waters absorb the sun’s heat more readily instead of reflecting it as the light-colored ice does, accelerating the heating effect. Using NASA’s ICESat spacecraft, scientists figured that overall Arctic sea ice thinned about 7 inches a year since 2004, for a total of 2.2 feet over four winters. Their findings were reported in the Journal of Geophysical Research-Oceans. The total area covered by thicker, older ice that has survived at least one summer shrank by 42 percent. … The research team blamed these changes on recent warming and anomalies in sea ice circulation. “We’re losing a lot more of the old ice, and that’s significant,” said Ron Kwok of the Jet Propulsion Laboratory in Pasadena, California. “Basically we knew how much the area (of ice) was shrinking, but we didn’t know how thick it was.” …
