Melting Sea Ice
05.05.2008 - Other
The September 2007 record low minimum extent of the Arctic sea ice could be broken this fall for the third time in five years. According to the calculations of scientists from the University of Colorado at Boulder, the minimum extent of the Arctic sea ice has a three-in-five chance of reaching a new record low in 2008. Things in Antarctica, however, are a little different.
Arctic Sea Ice Extent Could Head Towards New Record Low in 2008
Using satellite data and ocean buoys, the scientists recorded the thickness, roughness, snow depth and ridge characteristics, in order to track and measure sea ice sections over the years. Overall, 63 percent of the Arctic ice cover is younger than average, while just 2 percent is older than average. "The current Arctic ice cover is thinner and younger than at any previous time in our recorded history, and this sets the stage for rapid melt and a new record low", says Research Associate Sheldon Drobot.
The continued warming temperatures and preponderance of younger and thinner ice mean there is a 59 percent chance the Arctic ice extent will reach a new minimum low at the end of this year's summer. This means that the Northern Sea Route, extending from the Atlantic Ocean to the Pacific Ocean along the Russian coastline, may also open up this summer, and that it is "quite possible" the North Pole could encounter extensive ice-free zones.
Arctic versus Antarctic Sea Ice Extent
While the Arctic's summer sea ice has been declining more rapidly than what climate models had projected, the stability and amount of Antarctica's sea ice has not presented any surprises. An international team of scientists, including a National Oceanic and Atmospheric Administration (NOAA) oceanographer, examined and compared the way sea ice is likely to respond to global warming at both poles.
James Overland, from the NOAA points out that new factors (additional warming of the ocean, overall thinning of the sea ice) are bringing the Arctic sea ice into a state of no return. Climate models having integrated greenhouse gas emissions alone are now obsolete. As for Antarctica, the only area having recorded a significant temperature increase is the Antarctic Peninsula, where the Wilkins Ice shelf recently collapsed in late February. The reasoning behind such a difference is that the Antarctic ozone hole actually strengthens the atmospheric circulation (called Southern Annual Mode, or SAM). However, as the ozone hole recovers, the central plateau of Antarctica is expected to warm too, causing a decline in Antarctic sea ice extent.
