Decline In Arctic Sea Ice Caused By Unusual Winds, Not Warming

The supposedly drastic and unusual melting of Arctic sea ice this past summer has made the news recently. The cause has always been attributed to global warming, which many people want us to believe is caused by man's carbon dioxide emissions.

However, here is an alternative theory. Scientists at NASA now say the disappearance of the ice may be caused by unusual winds, not purely warming. I wonder if they have told Global Warming Jim Hansen about this?
Peter

Recent Rapid Decline in Arctic Sea Ice caused by Unusual Winds, says NASA
Post below lifted from Accuweather. See the original for links and graphics
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.

Website Devoted To Cryosphere

The following is from a very cool website concerned with the Earth's "cryosphere", that which is covered in ice. The site is worth saving and referring to.
Peter

from: http://arctic.atmos.uiuc.edu/cryosphere/



A webspace devoted to the current state of our cryosphere
Archive of daily polar sea ice cap concentrations (1979 - present)
Dowload the historical sea ice dataset here
Questions and/or comments to William Chapman
sea ice animations: 1978-2006 (46 MB quicktime) 2001-2006 (11 MB quicktime)
recent ice area
hemispheric ice area
hemispheric anomaly
seasonal sea ice

tale of the tapeThursday, August 9, 2007 - New historic sea ice minimum
Today, the Northern Hemisphere sea ice area broke the record for the lowest recorded ice area in recorded history. The new record came a full month before the historic summer minimum typically occurs. There is still a month or more of melt likely this year. It is therefore almost certain that the previous 2005 record will be annihilated by the final 2007 annual minima closer to the end of this summer.
In previous record sea ice minima years, ice area anomalies were confined to certain sectors (N. Atlantic, Beaufort/Bering Sea, etc). The character of 2007's sea ice melt is unique in that it is dramatic and covers the entire Arctic sector. Atlantic, Pacific and even the central Arctic sectors are showing large negative sea ice area anomalies.

While we use sea ice concentration data supplied by NASA via the National Snow and Ice Data Center (NSIDC), there are some differencesbetween the way we and NSIDC process our sea ice indices. NSIDC uses 10-day running means; we use 3-day running means. NSIDC will often report sea ice extent indices and records, we are reporting a new sea ice minima sea ice area. The ice area metric includes year-to-year variations within the central pack ice and not just variations in the southern sea ice edge. Regardless of these differences, the rapid rate of sea ice melt this summer, along with the current negative sea ice anomalies almost guarantees a record Northern Hemisphere summer sea ice minimum this summer, by any metric.
Follow this link for some background information on historic sea ice minima.

"Simply Incredible" Shrinking Of Floating Arctic Ice

There is a large amount of evidence that the Earth's climate is warming. The questions are: Is this unusual? What are the causes? Is it necessarily bad? Is there anything that can realistically be done to halt or reverse the global warming?
Peter


Analysts See ‘Simply Incredible’ Shrinking of Floating Ice in the Arctic
By ANDREW C. REVKIN
Published: August 10, 2007
The area of floating ice in the Arctic has shrunk more this summer than in any other summer since satellite tracking began in 1979, and it has reached that record point a month before the annual ice pullback typically peaks, experts said yesterday. The cause is probably a mix of natural fluctuations, like unusually sunny conditions in June and July, and long-term warming from heat-trapping greenhouse gases and sooty particles accumulating in the air, according to several scientists.

William L. Chapman, who monitors the region at the University of Illinois Urbana-Champaign and posted a Web report on the ice retreat yesterday, said that only an abrupt change in conditions could prevent far more melting before the 24-hour sun of the boreal summer set in September. “The melting rate during June and July this year was simply incredible,” Mr. Chapman said. “And then you’ve got this exposed black ocean soaking up sunlight and you wonder what, if anything, could cause it to reverse course.”

Mark Serreze, a sea-ice expert at the National Snow and Ice Data Center in Boulder, Colo., said his center’s estimates differed somewhat from those of the Illinois team, and by the ice center’s reckoning the retreat had not surpassed the satellite-era record set in 2005. But it was close even by the center’s calculations, he said, adding that it is almost certain that by September, there will be more open water in the Arctic than has been seen for a long time. Ice experts at NASA and the University of Washington echoed his assessment.

Dr. Serreze said that a high-pressure system parked over the Arctic appeared to have caused a “triple whammy” — keeping away clouds, causing winds to carry warm air north and pushing sea ice away from Siberia, exposing huge areas of open water. The progressive summertime opening of the Arctic has intensified a longstanding international tug of war over shipping routes and possible oil and gas deposits beneath the Arctic Ocean seabed.

Last week, Russians planted a flag on the seabed at the North Pole. On Wednesday, Stephen Harper, the Canadian prime minister, began a tour of Canada’s Arctic holdings, pledging “to vigorously protect our Arctic sovereignty as international interest in the region increases.”