Ice cliffs are causing mountain glaciers in High Mountain Asia to melt more rapidly, with only those facing north surviving over the glaciers, according to a new study published today (10 April) in the journal Proceedings of the National Academy of Sciences, PNAS.
Researchers from Northumbria University in the UK and the Swiss Federal Institute of Technology, ETH Zurich, in Switzerland have studied debris-covered glaciers that feature the spectacular phenomenon of ice cliffs in Nepal. These glaciers form part of the High Mountain Asia debris-covered glaciers which seem to experience anomalously high losses of mass.
Unlike the white ice glaciers of the Arctic and Antarctic regions, glaciers in many mountain ranges are covered in debris of rock from surrounding slopes. This debris layer can alter the way that the glacier responds to the climate. A thick layer of debris insulates the underlying ice and so decreases its melting rate, while a thin layer of a few centimetres offers less insulation cover, meaning the glaciers experience increased absorption of solar radiation, which therefore increases their melt rate.
Given that most glaciers have debris above a few centimetres, this should insulate the underlying ice and reduce glacier mass losses. However, debris-covered glaciers in High Mountain Asia seem to be losing mass at similar rates as clean ice glaciers in the same regions, prompting an intense current debate around a so-called “debris-cover anomalyâ€. Read more.