Big glaciers and glaciers in winter can be difficult to diagnose. In winter and spring, a thick blanket of snow covers most glaciers. During this time, seeing glacier health indicators like moraine and trim lines is more difficult, but still possible. Diagnosing glacier health on some big glaciers, such as the Kahiltna Glacier on Denali, presents another problem. On Denali, most climbers fly to 7,000 feet on the Kahiltna and spend their entire trip on a thick seasonal snowpack where the glacier appears fat and happy. In these situations, observe the melt zone on the flights in and out, looking for trim lines, fresh moraine, and moraine-dammed lakes.
Every season us mountaineers find changing climbing conditions in the glaciated mountains. As glaciers melt down, bergschunds become wider, making route access more difficult. Once on the route, you’ll find steep glacier headwalls normally covered by spongy neve have become black ice. And with less neve, you’ll see more rockfall, such as during the heat waves in 2003 and 2015 that closed Mont Blanc. But as glaciologist Keith Echelmeyer told me, “All change is not so bad—some routes may become more challenging and fun.”