Glacier changes on the Tibetan Plateau derived from Landsat imagery: mid-1970s-2000-13

Glacier area changes on the Tibetan Plateau were studied in different drainage basins based on Landsat satellite images from three epochs: 263 in the mid-1970s, 150 in 1999-2002 and 148 in 2013/14. Three mosaics (M1976, M2001 and M2013) with minimal cloud and snow cover were constructed, and the uncertainty due to each epoch having a finite span was accounted for. Glacier outlines (TPG1976, TPG2001 and TPG2013) were digitized manually with guidance from the SRTM DEM v4.1 and Google Earth imagery. To achieve complete multi- temporal coverage in a reasonable time, only debris-free ice was delineated. Area mapping uncertainty was evaluated at three study sites, Mount Qomolangma (Everest), Mount Naimona'Nyi, Mount Geladandong, where the largest differences between present and earlier measurements were within similar to +/- 4%. Area differences with previous inventories ranged from - 19.6% (TPG1976 minus the first Chinese Glacier Inventory) to -3.6% and -1.1% (TPG2013 and TPG2001, respectively minus the second Chinese Glacier Inventory), while the difference TPG2001 minus the GAMDAM Glacier Inventory was + 10.4%. Glacier area on the plateau decreased from 44 366 +/- 2827 km(2) (1.7% of the study area) in the 1970s to 42 210 +/- 1621 km2 in 2001 and 41 137 +/- 1616 km2 in 2013. Shrinkage was faster in external drainage basins of the southeast than in the interior basins of the northwest, from a maximum of -0.43% a(-1) (-1.60% a(-1) during 19942013) in the Mekong catchment down to a minimum of - 0.12% a(-1) in the Tarim interior drainage.