When we discuss sea ice here at NWF, we’re usually talking about polar bears. But this month, the annual loss of sea ice in the Arctic is affecting another marine mammal: walruses.Right now, melting ice caused by climate change is putting thousands of Pacific walruses that were forced onto shore in Alaska at risk of hunger and death by stampede.
Like polar bears, walruses depend on the ice for food. They feed primarily on sea floor denizens like clams and snails, and use sea ice as a diving platform to reach their prey. However, their diving ability bottoms out at a depth of 200 meters. When the ice recedes from shore—as it has earlier and earlier in recent years—walruses are forced to abandon the ice.Sea ice also plays a role in the walrus lifecycle, as females give birth on the ice. When it begins to melt, mother and pup make the journey back to shore. With the ice receding further and further into deeper water, lifebecomes perilous for young pups:
Adult walrus use the sea ice as a resting platform; mothers leave the calves there and dive to the bottom for food.
“The young can’t forage for themselves,” Ashjian said. “They don’t know how to eat,” and are dependent on their mothers’ milk for up to two years.
When sea ice retreats to such deep water, as it did in 2004, there are no platforms in shallow waters for mothers to rest and to leave their calves while they feed, and the pairs become separated.
For pups that reach the shore, another danger awaits: stampede. When startled by hunters, planes or predators, the walruses panic in a rush for safety in the water. In 2010, more than 100 walrus corpses were found after one such stampede, and most were younger animals. Since them, nearby residents have taken steps to prevent stampedes—refusing to take tourists by boat to the shoreline, and limiting air and vehicle traffic.
Of course, that wouldn’t be necessary under normal circumstances. But warming temperatures and a corresponding lack of ice are becoming the new normal. In 2012 there was 55% less sea ice in the Chuckchi Sea than 1980. While the situation isn’t quite as bad this year, 2013 still counted as No. 6 for lowest amount of ice.
Big polluters are working to rollback the fight against global warming. Just yesterday, the Supreme Court refused to hear an appeal on a decision saying the Environmental Protection Agency can limit carbon dioxide pollution under the Clean Air Act. That ensures EPA can prepare pollution limits on existing power plants, the single largest producers of carbon emissions in America.