Rapid Thinning of Arctic Ice

The amount of thick, long-lived sea ice covering the Arctic Ocean has declined dramatically in the last six years, with ice thinning by an average of 2.2 feet from 2003 to 2008, according to a study by scientists from NASA and two universities. In 2003, 62 percent of the Arctic’s total ice volume was stored in the yards-thick ice that forms over decades, while 28 percent of ice volume was thinner ice that melts from summer to summer. But by 2008, those percentages had been reversed, with only 32 percent of Arctic ice composed of thicker, multi-year floes while 68 percent was thin, first-year ice. The study, published in the Journal of Geophysical Research, used satellites to measure how high the ice rose above sea level — a gauge of the ice’s thickness. The rapid loss of Arctic sea ice volume and extent is due to rapidly rising air temperatures and changing circulation patterns in the Arctic Ocean, scientists said. The thinning of sea ice is significant because the first-year ice melts in summer, exposing the dark ocean beneath, which then absorbs more heat from the sun, further intensifying Arctic warming. The loss of sea ice is having a detrimental effect on polar bears, which use the ice as a feeding platform.