Alaska Thaws, Complicating the Hunt for Oil

DEADHORSE, Alaska . Harry Bader slogged across a patch of America’s only Arctic shore, leaning into a late December gale that filled the midday twilight with blowing snow and sent the wind chill to 40 below.

Despite the weather, Mr. Bader, the state’s land manager for the oil-rich North Slope, was consumed with one thing – the warming climate. Oil-prospecting convoys in search of new deposits are allowed to crisscross the fragile tundra only when it is snowy and solid. But over three decades, rising temperatures have cut this frozen season in half, to 100 days from 200.