冰冻的见证：阿拉斯加古老冰川冰或揭示北半球气候历史

Ancient glacial ice melting out of Alaska’s eroding coastline may offer the Northern Hemisphere’s only glimpse into a pivotal climate chapter EVAN HOWELL, in Cape Blossom, Alaska The tundra along Alaska’s northwestern coast sprawls gently into the distance, shimmer- ing and waterlogged with the summer thaw. Humans once passed into North America here, before the great ice sheets retreated and seas rose, swal- lowing the Bering Strait land bridge. A helicopter thwacked away into clammy skies on this August morn- ing in 2025, leaving me and several researchers on a high bluff where the Chukchi Sea batters the tablelands. Bear spray in hand, I scrambled down a steep drainage to the cobble- stone beach. …