Alex Jones Sayra Tineo

Antarctica Antarctica accounts for about 90 percent of the world's ice*

What Artic Ice Does: Arctic sea ice reflects sunlight, keeping the polar regions cool and moderating global climate. According to scientific measurements, Arctic sea ice has declined dramatically over at least the past thirty years, with the most extreme decline seen in the summer melt season.

Albedo The term albedo (Latin for white) is commonly used to applied to the overall average reflection coefficient of an object.reflection coefficient For example, the albedo of the Earth is 0.39 (Kaufmann) and this affects the equilibrium temperature of the Earth. The greenhouse effect, by trapping infrared radiation, can lower the albedo of the earth and cause global warming.greenhouse effectglobal warming

Albedo

Ice naturally cools air and water masses, plays a key role in ocean circulation, and reflects solar radiation back into space. In recent years, Arctic sea ice has been declining. It seems that the thick, permanent ice that used to constitute the majority of Arctic ice has been replaced by thinner, seasonal ice that melts away during the summer months. So not only is the ice covering less area than ever before, but the ice that does form is thinner than ever before. In total, the scientists calculated that the ice pack shrank by 57 percent between 2004 and 2008, thinning by 2.2 feet.

Perennial sea ice—thicker ice that remains frozen throughout the summer. The amount of perennial sea ice is essentially an indicator of the long-term health of the ice.

Rising Temperatures This higher temperature may be causing some floating icebergs to melt, but this will not make the oceans rise. Icebergs are large floating chunks of ice. In order to float, the iceberg displaces a volume of water that has a weight equal to that of the iceberg. Submarines use this principle to rise and sink in the water by changing their weight.

IceSAT Satellite photos showing how warming reduced the thickness of Arctic ice between 2004 and 2008 courtesy of NASA. In the 30 plus years since scientists started using satellites to track the area of the Arctic ice cap, the size of the ice pack has gotten smaller and smaller Ice is Thinning:

Animals: A ribbon seal huddles on a Bering Sea ice floe. The decline in the sea's ice cover threatens the species and could also mean trouble for other creatures, including walruses and whales

Polar Bears Bears are not tied to a specific territories, they roam widely in search of food, often leapfrogging from berg to berg. Bears fitted with satellite collars have been tracked on long swims-up to 150 miles across open ocean. In some bear habitats disappearing sea ice is already forcing bears to make longer, riskier swims. Its rare to see dead bears on the ice, but in 2004 I found three, including one near Lancaster sound.

Polar Bears: Polar bears eat mostly seals and other fatty marine mammals that they hunt from the ice. Two-thirds of the world's polar bears could disappear by 2050 as global warming continues to melt the Arctic's sea icepolar bears

Polar Bear: These may be the first to die off. As the sea ice melts sooner each summer, the bears will be forced to come ashore earlier and face food shortages before they have stored enough fat to last through the season In some places—like the southern end of polar bear range in Canada's Hudson Bay—the sea ice melts in the summer. The bears then come onto land, where they have insufficient food until the sea ice refreezes in the fall.