Dark Arctic future

摘要

Summer was once an important time for reflection in the Arctic. Perhaps not for much longer: the Arctic Ocean now reflects 15 per cent less sunlight than it did 30 years ago. Aku Riihela of the Finnish Meteorological Institute and his colleagues looked at satellite measurements of reflectivity, or albedo, between 1982 and 2009 (Nature Climate Change, doi.org/ nct). He says the darkening is partly due to thinning ice and the formation of fissures, and partly because in the warmer air, ponds of liquid water form on the surface of the ice. The shallow ponds reduce albedo and increase the amount of solar radiation that the ice absorbs.