Polar bears resort to cannibalism as Arctic ice shrinks

Scientists have monitored sea ice conditions for about 50 years with the help of satellites. Changes in the past decade have been alarming to climate researchers and oceanographers.

"It is the second lowest on record. ... If anything, it is reinforcing the long-term trend. We are still losing the ice cover at a rate of 10 percent per decade now, and that is quite an increase from five years ago," Meier said. "We are still heading toward an ice cover that is going to melt completely in the summertime in the Arctic."

Arctic ice helps regulate and temper the climate in many other parts of the world. The less ice there is, the more dramatic the impact. Huge sheets of ice reflect solar radiation, keeping our planet cool. When that ice melts, huge expanses of darker, open ocean water absorb the heat instead, warming things up.

Although few humans live in the Arctic, the disappearance of this ice cover can have effects far beyond the few residents and the wildlife of this harsh region. Ice cover loss can influence winds and precipitation on other continents, possibly leading to less rain in the western United States and creating more in Europe.

"That warming is going to spread to the lower latitudes, to the United States, and it's going to affect storm systems and storm tracks, the jet stream; that's going to affect crops and all sorts of things," Meier predicted.

So, just how much ice is disappearing?

Less than 30 years ago, there would still be 7 million square kilometers or 2.5 million square miles of ice left at the end of an Arctic summer. That's now dropped by almost 40 percent.

"Seven million square kilometers roughly corresponds to an area of the lower 48 United States. So back in the early 1980s, the lower 48 states would be covered in sea ice in the summer," Meier said. "Now we've essentially lost sea ice east of the Mississippi River and even beyond. So that's a significant amount of area."

The best known consequence of disappearing sea ice in the Arctic is the loss of the polar bear habitat.

"The Arctic sea ice melt is a disaster for the polar bears," according to Kassie Siegel, staff attorney for the Center for Biological Diversity. "They are dependent on the Arctic sea ice for all of their essential behaviors, and as the ice melts and global warming transforms the Arctic, polar bears are starving, drowning, even resorting to cannibalism because they don't have access to their usual food sources."

Scientists have noticed increasing reports of starving Arctic polar bears attacking and feeding on one another in recent years. In one documented 2004 incident in northern Alaska, a male bear broke into a female's den and killed her.