President Barack Obama looks at Bear Glacier, which has receded 1.8 miles in approximately 100 years, while on a boat tour to see the effects of global warming in Resurrection Cove, Tuesday, Sept. 1, 2015, in Seward, Alaska. Obama is on a historic three-day trip to Alaska aimed at showing solidarity with a state often overlooked by Washington, while using its glorious but changing landscape as an urgent call to action on climate change. (AP Photo/Andrew Harnik)