The NASA news release is here.
Write up from AccuWeather:
In a news release from NASA Monday, a group of scientists have determined that unusual winds caused the rapid decline (23% loss) in winter perennial ice over the past two years in the northern hemisphere. This drastic reduction is the primary cause of this summer’s fastest-ever sea ice retreat in recorded history which has lead to the smallest extent of total Arctic coverage on record.
According to the NASA study, the perennial ice shrunk by an area the size of Texas and California combined between the winter of 2005 and the winter of 2007. What they found was the Arctic Ocean north of Siberia and Alaska was dominated by thinner seasonal ice that melts faster compared to the thicker ice confined to the Arctic Ocean north of Canada. The thinner ice is more easily compressed and responds more quickly to being pushed out of the Arctic by winds.
“Unusual atmospheric conditions set up wind patterns that compressed the sea ice, loaded it into the Transpolar Drift Stream and then sped its flow out of the Arctic,” said Son Nghiem of NASA’s Jet Propulsion Laboratory and leader of the study. When that sea ice reached lower latitudes, it rapidly melted in the warmer waters.
What about these unusual wind patterns. Well, the article does not go into that too much, but I must believe some of this is due to changes in the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) which are large atmospheric circulations which have major impacts on the weather in certain parts of the world.
If you look at the two graphics below, you will notice that both the AO and the NAO have been predominately in the positive phase (red) between 1989-1995 and again from 1999 to current. The positive phase of the (AO) typically leads to milder than normal winters over Scandinavia and Siberia, while colder than normal conditions prevail across Greenland. The positive phase of the NAO again leads to colder conditions over Greenland, while much of the eastern U.S. is warmer than normal in general.
Thanks to Marc Morano for sharing this.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
“Nghiem said the rapid decline in winter perennial ice the past two years was caused by unusual winds. “Unusual atmospheric conditions set up wind patterns that compressed the sea ice, loaded it into the Transpolar Drift Stream and then sped its flow out of the Arctic,” he said. When that sea ice reached lower latitudes, it rapidly melted in the warmer waters.
“The winds causing this trend in ice reduction were set up by an unusual pattern of atmospheric pressure that began at the beginning of this century,” Nghiem said.
The Arctic Ocean’s shift from perennial to seasonal ice is preconditioning the sea ice cover there for more efficient melting and further ice reductions each summer. The shift to seasonal ice decreases the reflectivity of Earth’s surface and allows more solar energy to be absorbed in the ice-ocean system.”
Alarmism? Just goes to show how a small change in one place, sets up a system to be knocked over by a change in another place.
Phew that’s a relief.
http://tamino.wordpress.com/2007/10/01/explain-this/
Strange how denialists would now like “oscillation adjusted” but have not been keen to do that with 1998 El Nino. The ice will probably just pop back into place soon enough.
I may start deleting the word ‘denialist’ as it is not appropriate.
http://wattsupwiththat.wordpress.com/
but but but …
Gee, and something caused the antarctic ice area maximum of 2007 — it just wasn’t Tamino’s perpetual hot air (in head and out of blog).
McCall
the southern hemisphere is going to respond more slowly than the north, due to the greater ocean area, and the Antarctic is going to respond differently to the Arctic, due to it being mostly land, with a mountain range, and the different makeup of the atmosphere in terms of ozone and other gases. The slight increase (IIRC) was not in any way on the scale of the massive decrease in the Arctic. (Look at Lukes link)