Polar scientists are celebrating an anniversary of sorts. Thirty-five years ago, sea ice research took a great leap forward. On October 26, 1978, the Scanning Multichannel Microwave Radiometer (SMMR) beamed its first data records back down to Earth. The instrument, pronounced simmer, was capable of mapping global sea ice concentration and extent, giving scientists a more comprehensive look at Arctic and Antarctic sea ice. Thanks to SMMR and its successor remote sensing instruments, scientists now have a long and detailed record of sea ice that helps them understand how sea ice works, and how it is changing. Continue reading
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 warming alters the Arctic landscape, people are paying more attention to the changes happening to the Greenland Ice Sheet. The ice is melting more rapidly than before, leaving us to wonder, what’s going on?
To help answer your questions about Greenland, NSIDC’s newest Web site, Greenland Ice Sheet Today, will feature the latest research and imagery that researchers are using to monitor the ice. Scientists are discovering that while the ice sheet is in no danger of instantly melting, it is not immune to the Arctic’s rising temperatures. Continue reading
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
In April, average ice extent in the Arctic Ocean was right near the long-term average for the month. Ice extent even reached a near-record high in the Bering Sea, and still remains above average for that region. Does this mean that the Arctic sea ice has stopped declining? Is it starting to recover?
Unfortunately, scientists say no—and they are not surprised to see such a short upward bump in ice extent. “This does not indicate that the Arctic sea ice is recovering,” said Marika Holland, a sea ice expert at the National Center for Atmospheric Research (NCAR). Instead, the higher ice extent this year compared to recent years likely just reflects different weather this winter compared to last winter. “Sea ice exhibits large natural variability due to year-to-year variations in weather,” she said. Continue reading