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.
One of the three major ice streams studied, the outlet of the Jakobshavn-Isbræ glacier produces about 10 percent of Greenland’s icebergs due to calving. Located in West Greenland, its icebergs float down the fjord, sometimes getting stuck in shallower waters for years. Though the glacier’s acceleration rate has fluctuated through the years, it is still a major contributor to Greenland’s ice loss. Courtesy Spencer Weart, flickr (http://www.flickr.com/photos/weartpix/4077525679/)
For the past decade, Greenland’s ice sheet has been losing its ice more rapidly, raising concerns about its contribution to sea level rise. A recent study, published in Nature, proposes that Greenland could slow its shedding of ice from its massive ice sheet into the ocean. “This doesn’t mean glacial recession and melting will slow,” said Faezeh M. Nick, a glaciologist from the University Centre in Svalbard in Norway. Nick’s study points out that the problem is not so straightforward. Continue reading →
In February, polar climate researchers gathered at the National Center for Atmospheric Research in Boulder, Colorado to discuss the newest updates to models of the Earth’s climate system. The researchers are working together to create better models of the Arctic and Antarctic climates, which will feed into larger models of the whole Earth that help scientists understand how climate will change in the future. What goes into a climate model, and what can scientists learn from models that they cannot learn from observations?
What’s in a model?
Computer climate models are based on scientists’ understanding of Earth’s climate. The models use mathematical relationships to try to quantify the relationships between parts of the climate system. If you tweak one factor in climate, how does the simulated climate system respond? Models that bring many factors together help scientists learn how the climate system works, and let them run simulations on Earth’s climate. They also allow scientists to assess how climate may be affected by present and future changes in greenhouse gases and solar forcing, and how much of a role natural variability plays. Continue reading →