Core of climate history

Lou and the Ice Core Drill

Scientists take ice core samples in cold, windy, and forbidding environments. After drilling through solid ice to retrieve a core, initial measurements are taken before it is sent away for more in-depth analysis and storage. Photo credit: NSIDC courtesy Ted Scambos and Rob Bauer

People have asked how scientists know that today’s climate situation is unusual. Hasn’t the Earth undergone many cold and warm cycles before? Could this just be another? Buried in the world’s ice sheets is a long story of climate on Earth–and the contribution of atmospheric CO2 to warming or cooling. Scientists can access a unique and detailed look at the history of the Earth’s atmosphere through ice cores and start to understand the recent climate in context of past ones. Continue reading

Are scientists conservative about sea ice?

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)

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.

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What is the Arctic’s new normal?

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)

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

Are Greenland’s galloping glaciers slowing down?

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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

A greener Arctic

As higher temperatures create more temperate environments across parts of the Arctic, vegetation is creeping northward. Places like Denali National Park in Alaska may soon see forests encroaching on what are currently tundra biomes. Photo credit: Timothy Wildey (http://www.flickr.com/photos/timothywildey/4964905772/)

If gardening in icy Greenland sounds unbelievable, think again. A chef in Kangerlussuaq has started growing tomatoes, peppers, herbs, and even strawberries for his restaurant, and Greenland’s potato production doubled between 2008 and 2012. These agricultural feats would have been impossible only a hundred years ago. The Arctic has been warming over the past several decades at a rate twice as fast as the rest of the globe. As the region warms, several teams of scientists have been tracking changes in Arctic vegetation, trying to see if higher temperatures mean more green. Continue reading