-- Thousands of Pacific walrus were captured by a photographer as they came ashore on the northwest coast of Alaska last week, in an event believed to be triggered by global warming.
Researchers say less sea ice, brought on by climate change, forced the walruses to haul out for rest on land. According to scientists with the U.S. Geological Survey, walruses prefer to haul out on sea ice, rather than on land.
Hauling out on land could put young walruses at risk of being trampled, and it could be difficult for the marine mammals to find sufficient food close to shore, scientists say.
These photographs, made by Gary Braasch, were taken near Point Lay in Alaska on Aug. 23.
Increasingly large numbers of walrus have been documented coming to shore on the Alaskan coast for about eight years. Last year, an estimated 35,000 walruses came to shore.
These photos were taken just one week before President Obama's scheduled visit to Alaska on Monday, where he is expected to urge more action to fight global warming.
The Associated Press contributed to this report.