UW News

September 21, 2007

Experts list: Arctic sea ice minimum for 2007 sets new record

News and Information

The National Snow and Ice Data Center in Boulder, Colo., announced Thursday that the sea-ice extent minimum for 2007 was reached Sunday at a record-breaking low of 1.59 million square miles, or 4.13 million square kilometers.

A media alert from the center said, “Compared to the long-term average, the Arctic has lost an area of sea ice the size of the states of Alaska and Texas combined — or, the size of ten United Kingdoms.” See http://nsidc.org/news/press/2007_seaiceminimum/20070810_index.html.

University of Washington experts available to comment on the new minimum:

Ignatius Rigor
(206) 685-2571
Research scientist with the UW’s Applied Physics Laboratory
Models sea ice changes and is the current coordinator of the International Arctic Buoy Program, which has nearly 200 buoys in place this year.

About the new ice-extent record Rigor writes:
“During the past decade we have seen record minima in summer sea ice extent. These minima are typically related to warmer temperatures, but changes in wind related to the Arctic Oscillation may play a more important role by blowing the older, thicker sea ice out of the Arctic Ocean. The new, thinner sea ice that grows in its place simply has less mass to survive the summer melt. This dramatic decrease in the average age of sea ice on the Arctic Ocean sets the stage for the record minima that we have seen during the past decade.”

See 2004 press release “Winds, ice motion root cause of decline in sea ice, not warmer temperatures” at http://uwnews.org/article.asp?articleID=7070.  

Ronald Lindsay
(206) 543-5409
Meteorologist with the UW’s Applied Physics Laboratory
Lindsay’s research interests include arctic climate, climate change, sea ice mechanics and modeling, and remote sensing.

About the new ice extent record Lindsay writes:
“Nobody knows for sure, but it is possible that these large areas haven’t been open in thousands of years. The dramatic increase in open water seen this year may be the culmination of a process that began in the early ’90s when the system passed a ‘tipping point’ and allowed much more solar heat to be absorbed than before. This tipping point may have occurred because of a gradual warming of the region caused by global warming linked to greenhouse gases, a ‘kick’ caused by the shift in the wind patterns in the early ’90s and the positive ice-albedo feedback.

“The ice-albedo feedback concerns how much of the sun’s rays are reflected back to the atmosphere. An important change in the Arctic has been the increase in dark (low albedo) summer open water and thin ice that allows the ocean to absorb much more of the abundant summer solar heat. This heat in the ocean slows the growth of ice in the subsequent winter, and the thinner winter ice melts more quickly the following summer, a manifestation of the positive ice-albedo feedback.”

See 2005 press release “Scientists believe open water in summer has become key to declining arctic ice” at http://uwnews.org/article.asp?articleID=12459.  

Richard Moritz
(206) 543-8023
Principal oceanographer, UW’s Applied Physics Laboratory
Moritz is interested in the physics of climate, and the interactions among ocean, sea ice and atmosphere. He is actively engaged in climate modeling research and was the leader of Ice Station SHEBA that froze an icebreaker into the ice pack for a full year to serve as a base camp for scientists conducting research.

Moritz writes:
“Analyses of the 2007 ice budget are in press or underway. It seems very likely that the ice was initially thin (compared to the average of the preceding 30 years), and that the wind anomalies moved ice away from the coasts of Alaska and East Siberia and towards Greenland and Svalbard during the melting season. Also likely is that the large area of open water absorbed lots of sunlight, warmed the ocean surface, and contributed to additional melting at the edges of the ice pack.

“The anomalously thin ice at the end of winter is at least partly associated with a multidecadal downward trend in ice thickness, and the leading explanation for that trend is greenhouse warming (locally in the Arctic and remotely in source regions for the poleward heat transport).

“The state of the ice cover (for example, thickness and age) changed markedly in the late 1980s/early 1990s associated with the large, long-lived Arctic Oscillation/North Atlantic Oscillation anomaly. That Arctic Oscillation/North Atlantic Oscillation anomaly event is not directly attributable to greenhouse warming – although climate models indicate the probability of positive Arctic Oscillation/North Atlantic Oscillation anomalies increases with global warming. The changes wrought by that event (for example, loss of old ice) affect the state of the ice even now, in 2007.”

Cecilia Bitz
(206) 543-1339
Assistant professor of atmospheric sciences and physicist with the UW’s Applied Physics Laboratory
Bitz is interested in high-latitude climate, climate change and variability.

Bitz writes:
“This is an alarming record. My research is devoted to predicting sea ice cover and the role of sea ice in climate. I co-authored a paper with Marika Holland and Bruno Tremblay about rapid sea ice retreat in December 2006, about a model that predicted an ice-free Arctic in September was possible as early as 2040. According to our model, with the current level of global warming, the sea ice can recover from an anomaly of the magnitude we are seeing today. But with increasing greenhouse gas concentrations and greater warming expected by about the year 2025, the Arctic would probably not recover and the retreat would continue at a very high rate for about another 15 years, when there would be essentially no ice left in September.”

John “Mike” Wallace
(206) 543-7390
Professor of atmospheric sciences
Wallace’s research interests concern global climate and its year-to-year and decade-to-decade variations, including the Arctic Oscillation.

Wallace writes:
“The extraordinarily low minimum in sea ice extent this year comes as a surprise, even to those of us who have been following the retreat of the ice over the past 30 years. We were expecting another record low year this year, but we weren’t expecting to break the record by such a big margin. I think this news will shorten the timetable for projections of ice-free summers over most of the Arctic.”

See the 2001 press release “UW scientists say Arctic oscillation might carry evidence of global warming” at http://uwnews.org/article.asp?Search=Arctic&articleid=3261.  

Harry Stern
(206) 543-7253
Mathematician with the UW’s Applied Physics Laboratory
Stern analyzes satellite data relating to sea ice motion, thickness and deformation.

Stern writes:
“I estimate the average of the ice extent for September 2007, based on National Snow and Ice Data Center information so far this month, will be about 1.74 million square miles. Comparing that to the average ice extent for the months of September going back to 1979, the drop from 2006 to 2007 is the largest one-year drop in the whole satellite record, and it comes on top of the near-record low in 2006. In terms of the average September ice extent for the years 1979 to 2000, which the snow and ice data center uses as a baseline, this year is 35% below that baseline.

“If we had used this long-term trend of September averages to predict the 2007 sea-ice extent from the 2006 value, we would have predicted 2.24 million square miles. In fact, 2007 will come in around 1.74 million square miles, or 500,000 square miles less than the prediction based on the long-term trend. Any given year might be below the long-term trend, but 2007 is way below, compared to the typical fluctuations above and below that trend during 1979-2006.”

James Morison
(206) 543-1394
Principal oceanographer, UW’s Applied Physics Laboratory
Morison leads the North Pole Environmental Observatory program, a National Science Foundation-funded project that for the last eight years has conducted work near the North Pole, monitoring conditions of the ice, oceans and such. Camps usually run from mid-April to mid-May.

Morison writes:
“The ice cover is reduced to the point that it will be hard to find any thick multiyear ice. Not only is this alarming from the standpoint of being a possible tipping point for the environment, it will possibly raise springtime operational challenges for us starting next year.”