The U.S. Coast Guard Cutter Healy encountered only small patches of sea ice in the Chukchi Sea when this photograph was taken on July 20, 2011. (Courtesy NASA Goddard Space Flight Center)
Guest post by Walt Meier, NSIDC Scientist
Arctic sea ice set a record minimum extent in September 2012, far below the previous record low in 2007. Summer extents have been far lower than average for the last decade, with several record or near-record years. Looking at the numbers, one is tempted to think that the Arctic Ocean may reach nearly sea ice-free conditions within just a few years. But most expert analyses indicate that we’re likely at least a couple decades away from seeing a blue Arctic Ocean during the summer.
Although Arctic sea ice extent as of June 2013 falls within the normal range, sea ice overall is still declining compared to the average. This photograph was taken in August 2009, when sea ice extent nears its lowest annual extent before refreezing for the winter. (Courtesy Patrick Kelley, United States Coast Guard)
NSIDC recently switched the baseline against which we analyze Arctic sea ice extent. Previously, we relied on a baseline that coincided with the beginning of the satellite period and stretched 20 years, from 1979 to 2000. The new baseline runs from 1981 to 2010, covering 30 years. Why did we make such a change?
Switching to a 30-year baseline allows us to be consistent with other climate monitoring agencies, which commonly use a 30-year time period for conducting analyses. This new baseline also helps account for the wider variations observed in Arctic sea ice extent. Continue reading →
As the Arctic Ocean becomes increasingly ice-free, many countries are eager to tap into previously inaccessible northern resources. Energy companies seek drilling permits for oil and natural gas, and shipping companies hope to ply newly opened sea routes. Given the unpredictable nature of Arctic sea ice, some wonder if operating in the already inhospitable north will be an economically viable effort. Others believe that even if drilling or shipping is not currently viable, the Arctic is changing fast enough that industry in the Arctic is here to stay. Continue reading →
This graph shows the yearly trend toward later Arctic sea ice minimum dates, but also illustrates the wide variability from year to year. Credit: NSIDC
A reader recently asked if the date of the annual Arctic sea ice minimum is shifting later each year. And if so, is that shift a sign of heat being stored in the Arctic region?
According to the satellite record, Arctic sea ice generally melts to its minimum annual extent between the first and third week of September, after which ice begins freezing again. In recent decades, the Arctic has been gaining heat: Air, land, and ocean temperatures in the region have been slowly rising, and scientists have noted dramatic reductions in summer sea ice extent, as this heat causes more ice to melt away. But is this heat causing sea ice to form later each fall? Continue reading →
Sea ice extent reached a new record low on August 27, 2012 and continued to decline. The last six years have seen minimum sea ice extents below the two standard deviation range of the data. The graph above shows Arctic sea ice extent as of August 13, 2012, along with daily ice extent data for the previous five years. 2012 is shown in blue, 2011 in orange, 2010 in pink, 2009 in navy, 2008 in purple, and 2007 in green. The gray area around the average line shows the two standard deviation range of the data.
Satellite observations since 1979 show that sea ice melted to its lowest extent in the satellite record, during August 2012 . As of this post date, the ice continues to melt, with two to three weeks left before the days shorten enough for the ice extent to begin to expand through the winter. Readers often write to us asking what such records really mean. How far from normal is this year’s record low, and how do scientists decide what is normal? Continue reading →