Solar radiation (sunlight) is the main provider of energy for the melting
of snow and ice in Greenland. As the solar radiation reaches the ice sheet,
a large percentage is reflected back up; fresh snow reflects up to 90% of
sunlight. The ice reflectivity (a.k.a. albedo) therefore exhibits a strong
control on the melting of the ice sheet. However, Greenland ice albedo has
been decreasing since the beginning of satellite observations in 1981.
Change in summer albedo, blue colors showing darkening. Data were derived from MODIS (Moderate Resolution Imaging Spectroradiometer) observations.
A freshly fallen snow crystal has numerous facets to reflect sunlight (left). Warming causes the grains to round at the edges and clump together (right). Scanning electron microscope photos courtesy the Electron and Confocal Microscopy Laboratory, USDA Agricultural Research Service.