By SETH BORENSTEIN
AP Science Writer
WASHINGTON (AP) -- New NASA satellite measurements show that sea ice in the Arctic is more than just shrinking in area, it is dramatically thinning.
The volume of older crucial sea ice in the Arctic has shrunk by 57 percent from the winter of 2004 to 2008. That's losing more volume of ice than water in Lake Michigan.
NASA scientist Jay Zwally said global warming is to blame. He said rapidly shrinking sea ice in the Arctic warms the rest of the globe indirectly. Older ice is more important in the Arctic because it is thicker, surviving the heat of summer and building over time.