Photo by Ute Kaden.

What is sea ice? How is it formed? Why is it important? Who / What does sea ice impact? How do scientists study sea ice? What do scientists learn? What can I do? Iceberg near Barrow, Alaska. Photo by Photo by Misty Nikula (TREC 2004).

What is Sea Ice? Sea ice is found in the polar regions. Sea ice covers approximately 25 million square kilometers of the earth (about 2.5 times the size of Canada). Sea ice is made from frozen ocean water. As the ocean freezes, the salt collects in droplets called brine. Brine is eventually squeezed out—multi-year ice is fresh enough that melted, people can drink it. Ice breaker Healy surrounded by sea ice and melt ponds. Photo by Ute Kaden.

Why is Sea Ice Important? It provides life support for people who live in the Arctic and for animals that live above and below the ice. Sea ice is an important hunting grounds for people and animals. Sea ice provides shelter, birthing, and resting areas for animals. Sea ice keeps the polar regions cool. Sea ice reflects 80% of the sunlight. Open sea water absorbs 90% of the sunlight. Sea ice helps to regulate climate. It moderates ocean temperatures, which play a role in air temperature.

Ice Formation Once sea ice forms, it continues to grow through the winter. When temperatures increase in the summer, first-year ice begins to melt. If the ice is thick enough, and conditions are right, the entire ice sheet will not melt. Image courtesy of the National Snow and Ice Data Center (NSIDC). When it begins to grow again the following winter, it is called multiyear ice.

Frazil ice Picture courtesy of Don Perovich, U.S. Army Cold Regions Research and Engineering Laboratory. Rotting ice floe Photo by Maggie Prevenas (PolarTREC 2007). Courtesy of ARCUS. Grease ice, nilas, and rafting Photo by USFSW/Brad Benter. Courtesy of ARCUS. Pancake ice Photo by Ute Kaden (TREC 2005). Courtesy of ARCUS.

Sea Ice Impacts on Mammals A lack of sea ice or poor ice conditions cause stress for marine mammals and affect their abilities to reproduce.  Arctic Fox  Can get stranded  Migration routes become inaccessible  Hunting areas change  Caribou  Migration routes become inaccessible  Foraging becomes more difficult  Can fall through very thin ice during migration. Expected reductions in sea ice will shrink marine habitats and may push some species to extinction. Arctic fox. Image courtesy of the National Snow and Ice Data Center. Caribou. Image courtesy of the National Snow and Ice Data Center.

Sea Ice Impacts on Seals Many seals (harp, hooded, ringed, bearded, spotted, and ribbon seals) live in the Arctic along the sea ice edge. Ice is used for resting and birthing. Some seals use the snow on the ice to create dens. Seal mothers leave their pups on the ice while they hunt nearby. Spotted seal pup. Photo by Maggie Prevenas (PolarTREC 2007). Courtesy of ARCUS

Sea Ice Impacts on Walrus  Walrus feed near the edge of the continental shelf.  If the ice retreats too far, they must swim a great distance for their food—This raises their risk of drowning.  Decreasing sea ice extent would reduce the habitat for seals and walrus. Early ice breakup could result in the separation of mothers and pups, which would lead to higher death rates among newborn pups. Walrus herd in the Bering Sea. Photo by Maggie Prevenas (PolarTREC 2007). Courtesy of ARCUS. Walrus on ice floe. Marc Webber, U.S. Fish and Wildlife Service.

Sea Ice Impacts on Polar Bears Polar bears use multi- year ice as a platform for hunting seals. They must eat a lot during the winter in order to survive summers on land. The bears also build their dens on the ice. Polar Bear. Courtesy of Marc Webber, U.S. Fish and Wildlife Service. A mother bear and her two cubs. Photo by Ute Kaden (TREC 2005). Courtesy of ARCUS.

Sea Ice Impacts on People Small changes can have drastic consequences for people who subsist off the land. People rely on the sea ice for transportation, hunting, and shore protection. People must now change their hunting strategies and face more dangerous situations. Tsiigehtchic native elders clean fish at their fish camp. Photo by Amy Clapp (TREC 2005). Courtesy of ARCUS. Blanket toss in Barrow, Alaska. Photo by Misty Nikula- Ohlsen (TREC 2004). Courtesy of ARCUS.

Impacts on Hunting Loss of sea ice means the animals are farther away. Traveling a greater distance is both dangerous and expensive. Loss of sea ice can lead to: Accidents on thin ice. More severe storms. Inadequate storage. Hunters preparing to leave Barrow. Photo by Leslie Pierce (TREC 2005). Courtesy of ARCUS. Cutting up a raw section of a whale at the Nalukataq festival in Barrow. Photo by Misty Nikula-Ohlsen (TREC 2004). Courtesy of ARCUS.

How do Scientists Study Sea Ice? Sea ice is difficult to study, because it is in remote locations and the conditions are extreme. Scientists use several methods to study sea ice: Field Studies Remote Sensing Modeling Scientists set up sampling devices. Photo by Ute Kaden (TREC 2005). Courtesy of ARCUS.

Field Studies Fieldwork in the arctic is difficult, dangerous, and expensive. Scientists set up ice camps or study from icebreaker ships. They stay in the Arctic for a long period of time. They also leave instruments in the Arctic. These instruments collect data and send it back to the scientists when they are at their home institutions. Special instruments are used to study changes in sea ice, ocean, atmosphere, and biology. Collecting sea water samples from the ice edge in the Bering Sea. Photo by Robyn Staup (PolarTREC 2007). Courtesy of ARCUS. Collecting ice samples. Photo by Steve Roberts. Courtesy of ARCUS. Equipment for coring and sampling. Photo by Jerry Brown. Courtesy of ARCUS.

Remote Sensing Remote sensing means viewing something from a distance. Scientists use satellites to collect a variety of remote data: Visible Infrared Passive Microwave Active Microwave Red = sea ice undergoing active melting on the ice surface; Magenta = sea ice with reduced melt; Cyan = refrozen sea ice with residual wetness; White = sea ice refrozen for 10 or more days; Blue = ocean areas with less than 15 percent ice cover; Brown = land surfaces; Black = missing data. T = Northern Sea Route; V = Northwest Passage. Image courtesy of NASA/JPL/QuikScat Science Team.

Modeling A model is a mathematical representation of a real- world physical process. Scientists use models to simulate sea ice processes. Sea ice models provide valuable information on how sea ice evolves and how it will be affected by changing climate. Arctic sea ice summer minimum in September 2000, based on simulations produced by the Community Climate System Model. (Image © UCAR, at:

The arctic sea ice is melting at a faster rate than anyone predicted. Greenhouse gasses emitted through human activities have increased mean global temperatures. This is the mostly likely cause of the sea ice decline. The sea ice decline is VERY complicated, other factors are at play— The Arctic Oscillation, ice movement out of the Fram Strait, and wind patterns have also influenced the melt. Some scientists are learning more about sea ice change and alternative methods of study by participating in the Sea Ice Outlook.

What Can I Do? A major contributor to melting sea ice is global warming. To help slow global warming, and slow sea ice melt, there are several things you can do to reduce your carbon footprint. Change your lightbulbs Eat local Recycle Unplug unused electronics Ride your bike!

Take the Quiz! Now that you’ve learned all about sea ice, take the interactive Sea Ice Quiz and test your knowledge!