09/17/2012 05:10 pm ET Updated Nov 17, 2012

Arctic Ice Impeding Shell Oil Holds Promise for Pacific Walrus

A 30-by-12-mile chunk of sea ice floating tens of miles offshore of mainland Alaska in the Chukchi Sea, one of the nation's emerging oil frontiers, may have interrupted exploration in this corner of the Arctic Ocean. But that floe and others are a welcome change for thousands of Pacific walrus, which made long and treacherous journeys to reach Alaska shores in recent autumns.

For the last three years in a row, and in 2007, the massive mammals blanketed beaches, sometimes with fatal consequences. Walrus, which are under consideration for listing under the Endangered Species Act, can easily weigh a ton. When startled, the herd may evacuate at once, trampling and crushing animals while fleeing. This is believed to have happened in 2009, when more than 100 walrus, mostly juveniles, were found dead after a large haul-out at Icy Cape, on the Arctic Ocean shore southwest of Barrow. And it's thought that walrus have come ashore in increasingly large numbers recently after exhausting themselves in the search for sea ice on which they can rest and launch feeding forays into the rich waters of the continental shelf. A 2010 haul-out at Point Lay, not far from Icy Cape, was estimated to contain at least 10,000 animals.

Climate change, and its effect on marine life, has been one consideration in evaluating the survivability of Arctic species, including the polar bear. Some have asked whether the government should take steps to protect them on a warming planet. A decision on the Pacific walrus isn't expected until 2017.

This year's appearance of an ice floe tens of miles long -- nearly half the size of sprawling Chugach State Park near Anchorage -- has led to a counterintuitive notion among some non-scientists. Across the Arctic, ice retreated more than any other year on record this summer. With receding ice caps and huge swaths of open water persisting into fall, traveling ice chunks aren't the first image to come to mind. A popular -- but incorrect -- impression from the Arctic's big melt is that little ice is present in the northern seas this time of year. Not so. The ice drifting off of Alaska's coast is different from...

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