FILE - In this Aug. 4, 2012 file photo, tourists walk to Exit Glacier in Kenai Fjords National Park just outside Seward, Alaska. Global warming is carving measurable changes into Alaska, and President Obama is about to see it. Obama leaves Monday, Aug. 31 for a three-day visit to the 49th state in which he will speak at a State Department climate change conference and become the first president to visit the Alaskan Arctic. (AP Photo/Mark Thiessen)