25 FEATURE STORY Who’s Minding the Planet? GREENLAND ICELAND NUUK Capital pop. 18,000 Study Site Mid-Abalation Zone 3,205 m ABLATION ZONE Elevation breaks the glaciers that comprise the Greenland Ice Sheet into distinct zones. In the frigid higher elevations, glaciers have accumulation zones covered with snow and firn, the dense, compacted old snow that represents the middle ground between snow and glacial ice. At lower elevations, ambient temperatures are warm enough to melt away the snow and firn, leaving a bare ablation zone where ice melts, evaporates or sublimates in the sun. A team led by UCLA’s Laurence C. Smith worked in the mid-ablation zone, where runoff is high—just right for studying the evolution of the ice sheet and beginning to understand the future of glacial melting in a changing climate.