Global Warming Alert
April 03, 2007
The Arctic in 2005 saw little renewal of the thick, perennial sea ice that normally melts and is replenished every year, a NASA study has found. Renewing the layer is crucial to maintaining the summer ice cover's stability, and the new findings suggest it may continue to decrease by as much as 10 per cent a year. "The area of seasonal ice that survives the summer may no longer be large enough to sustain a stable perennial ice cover, especially in the face of accelerating climate warming and Arctic sea ice thinning." Perennial ice coverage was 14 per cent lower in January 2006 than it was at the same time in 2005 — only about four per cent of the 2.5 million square kilometers of seasonal ice formed the previous winter survived the summer. The depletion of the sea ice was also affected by ABNORMAL wind conditions that resulted in about seven per cent of the perennial ice coverage area migrating out of the Arctic — an UNUSUALLY HIGH amount.
ANIMATION: Click on Image below left to view in Flash format or Click on Image below right to View in Quick Time format
This animation, based on simulations produced by the Community Climate System Model, shows the year-to-year variability of Arctic sea ice. For much of the 20th century, the model accurately captures the expansion and contraction of the area covered by sea ice from one late summer to the next, based on natural climate cycles. By the end of the 20th century, however, the ice began to retreat significantly because of global warming.
Within a few decades or sooner, the model simulations show that the ice is likely to shrink abruptly, losing about two-thirds of its area over the course of about a decade. By about 2040, the Arctic may be nearly devoid of sea ice during the late summer unless greenhouse gas emissions are significantly curtailed. (Animation ©UCAR.)The image at left, based on simulations produced by the Community Climate System Model, shows the approximate extent of Arctic sea ice in September. The model indicates the extent of this late-summer ice could begin to retreat abruptly within several decades. By about 2040 (image at right), the Arctic may be nearly devoid of sea ice during the late summer unless greenhouse gas emissions are significantly curtailed. (Illustrations ©UCAR.)
Images and Animation provided by the National Center for Atmospheric Research