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These articles provide answers to frequently asked questions related to Earth's frozen realms. Questions range from general background information and detailed science processes to the data gathered and archived at the National Snow and Ice Data Center (NSIDC) and its data management programs including NOAA@NSIDC, the NASA NSIDC Distributed Active Archive Center (DAAC), and the Exchange for Local Observations and Knowledge of the Arctic (ELOKA). If you have a question that is not answered here, please contact NSIDC User Services.
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Freshly formed sea ice can be as thin as a few sheets of paper or as thick as a one-story house, depending on how long it has existed. Measuring sea ice thickness is harder than measuring how much sea ice covers the ocean surface but multiple approaches have been used.
Hurricanes form in the tropics, feeding on very warm ocean waters. As they track northward, they may transform to an extratropical storm with an added punch, sometimes reaching southern Greenland, Alaska, and even Arctic latitudes of the North Atlantic.
NSIDC archives satellite data for polar sea ice dating back to November 1978. The sharpest declines have occurred in the summer and fall, including the time of year when sea ice reaches its annual minimum in September. Although Arctic sea ice extent has not declined as much during winter months, it has still shown a steadily decreasing trend. Arctic sea ice extent now exhibits long-term declines in all months, including the coldest, darkest months of the year.
Although area and extent may sound synonymous, they are different measurements, rendering different numbers, even from the same satellite observations. Sea ice area is the total region covered by ice. Extent is the total region with at least 15 percent sea ice cover. NSIDC usually reports extent, which gives higher values than area.
About 70 percent of the planet’s freshwater is locked up in ice sheets: massive ice bodies spanning more than 50,000 square kilometers (20,000 square miles). Our planet has two ice sheets, one covering roughly 80 percent of Greenland and the other
A glacial lake is a body of water that originates from a glacier. It typically forms at the foot of a glacier, but may form on, in, or under it. As Earth’s climate warms, the world’s glaciers are shrinking, increasing freshwater outputs to all kinds