Changes of glacial lakes and implications in Tian Shan, central Asia, based on remote sensing data from 1990 to 2010

Changes of glacial lakes and implications were assessed for the Tian Shan Mountains from 1990 to 2010, based on Landsat Thematic Mapper/Enhanced Thematic Mapper Plus images. The total area of glacial lakes has expanded greatly over the last 20 years, at an average rate of 0.69 +/- 0.12 km(2) a(-1) or 0.8 +/- 0.1% a(-1). Eastern Tian Shan contributed nearly half that increase (approximate to 0.34 +/- 0.03 km(2) a(-1)), followed by northern Tian Shan at 0.17 +/- 0.03 km(2) a(-1). Both widespread climate warming and glacier shrinking led to glacial lake areal expansion, while small to medium (<0.6 km(2)) lakes responded most sensitively to glacier retreat. The closer the hydrologic connection of lakes to glaciers, the greater the areal expansion rate. An average approximate to 0.007 +/- 0.002 Gt a(-1) of glacier meltwater has been temporarily held in lakes over the past two decades. The increasing quantity of melt available for lake formation and growth may simultaneously increase the frequency and damage of glacial lake outburst floods or debris flows in this region. Sixty potentially dangerous glacial lakes are identified, among which 12 have an outburst probability status of 'high', 25 'medium' and 23 'low'.