By Gabriel Lewis, PhD candidate, Department of Earth Sciences, Dartmouth College, New Hampshire (US).
Image from GreenTrACS Video (greentracs.blogspot.com)
The stability of the Greenland Ice Sheet (GrIS) in a warming world is a critical research area with societally important implications for future sea level rise, with projected GrIS sea level contributions of at least 20 cm by 21001,2. Previous studies conclude that GrIS mass loss has been accelerating over the past decade, but spatial and temporal variations in GrIS mass balance remain poorly understood due to a complex relationship among precipitation and temperature changes, surface melt, runoff, ice discharge3, and surface albedo4. Satellite measurements indicate that albedo, the proportion of incoming solar radiation that is reflected by the glacier surface, has been declining over the past decade5,6, but the cause of the GrIS albedo change remains poorly constrained by field data. As fresh snow (albedo > 0.85)7 warms and melts, its albedo decreases due to snow grain growth, promoting solar absorption, higher snowpack temperatures and further melt8. However, dark impurities like soot and dust can also significantly reduce snow albedo, even in the dry snow zone2.