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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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Aerial photo of Karakoram glaciers
Most mountain glaciers outside the polar regions are losing ice, but in the Karakoram Range, glaciers have experienced modest gains. Glaciologists have proposed multiple explanations, currently favoring weather patterns unique to the region. Glaciologists have also pondered how long the anomaly is likely to persist in a warming climate.
Map of projected Last Ice Area of the Arctic Ocean
The term “ice-free” is based on a threshold for sea ice extent: the area of ocean with at least 15 percent sea ice concentration. A consensus has emerged among scientists that the Arctic Ocean is effectively ice free when its sea ice extent falls below 1 million square kilometers (390,000 square miles).
Palm trees on a flooded beach
Sea level rise from ice sheet loss will not be uniform and, ironically, sea levels near melting ice sheets will likely fall. Scientists anticipate that sea level will rise fastest along some densely populated coastal regions in the tropics and mid-latitudes.