President Barack Obama has crossed the Arctic Circle in a first by a sitting U.S. president, telling residents in a far-flung Alaska village that their plight should be the world’s wake-up call on global warming. Obama’s visit to Kotzebue, a town of some 3,000 people in the Alaska Arctic, was designed to snap the country to attention by illustrating the ways warmer temperatures have already threatened entire communities and ways of life in Alaska. He said despite progress in reducing greenhouse gases, the planet is already warming and the U.S. isn’t doing enough to stop it.