An abnormally cool Arctic is seeing dramatic changes to ice levels. In sharp contrast to the rapid melting seen last year, the amount of global sea ice has rebounded sharply and is now growing rapidly. The total amount of ice, which set a record low value last year, grew in October at the fastest pace since record-keeping began in 1979.
The actual amount of ice area varies seasonally from about 16 to 23 million square kilometers. However, the mean anomaly-- defined as the difference between the current area and the seasonally-adjusted average-- changes much slower, and generally varies by only 2-3 million square kilometers.
That anomaly had been negative, indicating ice loss, for most of the current decade and reached a historic low in 2007. The current value is again zero, indicating an amount of ice exactly equal to the global average from 1979-2000.
Bill Chapman, a researcher with the Arctic Climate Center at the University of Illinois, says the rapid increase is "no big deal". He says that, while the Arctic has certainly been colder in recent months, the long-term decrease is still ongoing. Chapman, who predicts that sea ice will soon stop growing, sees nothing in the recent data to contradict predictions of global warming.
Others aren't quite so sure. Dr. Patrick Michaels, Professor of Environmental Science at the University of Virginia, says he sees some "very odd" things occurring in recent years. Michaels, who is also a Senior Fellow with the Cato Institute, tells DailyTech that, while the behavior of the Arctic seems to agree with climate models predictions, the Southern Hemisphere can't be explained by current theory. "The models predict a warming ocean around Antarctica, so why would we see more sea ice?" Michaels adds that large areas of the Southern Pacific are showing cooling trends, an occurrence not anticipated by any current climate model.
On average, ice covers roughly 7% of the ocean surface of the planet. Sea ice is floating and therefore doesn't affect sea level like the ice anchored on bedrock in Antarctica or Greenland. However, research has indicated that the Antarctic continent -- which is on a long-term cooling trend -- has also been gaining ice in recent years.
The primary instrument for measuring sea ice today is the AMSR-E microwave radiometer, an instrument package aboard NASA's AQUA satellite. AQUA was launched in 2002, as part of NASA's Earth Observing System (EOS).