Search

Glaciers in tropical regions are very sensitive to climatic variations and thus strongly affected by climate change. The majority of the tropical glaciers worldwide are located in the Peruvian Andes, which have shown significant ice loss in the last century. Here, we present the first multi-temporal, region-wide survey of geodetic mass balances and glacier area fluctuations throughout Peru covering the period 2000–2016. Glacier extents are derived from Landsat imagery by performing automatic glacier delineation based on a combination of the NDSI and band ratio method and final manual inspection and correction. The mapping of debris-covered glacier extents is supported by synthetic aperture radar (SAR) coherence information. A total glacier area loss of -548.5±65.7 km 2 (-29 %, -34.3 km 2 a -1) is obtained for the study period. Using interferometric satellite SAR acquisitions, bi-temporal geodetic mass balances are derived. An average specific mass balance of -296±41 kg m -2 a -1 is found throughout Peru for the period 2000–2016. However, there are strong regional and temporal differences in the mass budgets ranging from 45±97 to -752±452 kg m -2 a -1. The ice loss increased towards the end of the observation period. Between 2013 and 2016, a retreat of the glacierized area of -203.8±65.7 km 2 (-16 %, -101.9 km 2 a -1) is mapped and the average mass budget amounts to -660±178 kg m -2 a -1. The glacier changes revealed can be attributed to changes in the climatic settings in the study region, derived from ERA-Interim reanalysis data and the Oceanic Nino Index. The intense El Niño activities in 2015/16 are most likely the trigger for the increased change rates in the time interval 2013–2016. Our observations provide fundamental information on the current dramatic glacier changes for local authorities and for the calibration and validation of glacier change projections. [ABSTRACT FROM AUTHOR]

Tropical glaciers are very sensitive to climatic changes and therefore strongly affected by global warming. Nearly all glaciers in the tropics are located in the Peruvian and Bolivian Andes, where significant glacier recession was reported since in the last century. Previous studies regarding ice mass loss and glacier retreat focus on specific mountain ranges or individual glaciers and consider different observation periods. In this study, we carried out the first multi-temporal, region wide analysis of geodetic glacier mass balances and area changes throughout Peru and Bolivia, by means of multi-sensor remote sensing, for the study period 2000-2016. A total glacier area loss of -29% (-37 km² a-1) is derived by automatic glacier mapping using Landsat imagery. Geodetic mass balances are derived from interferometric SAR acquisitions. An average specific mass balance of -395±55 kg m-2 a-1 is computed for the period 2000-2016. A strong regional and temporal variability in the mass balances ranging between 68±102 kg m-2 a-1 to -990±476 kg m-2 a-1 is found. For the period 2013-2016, increased glacier recession of -117 km² a-1 and a more negative mass budget of -753±178 kg m-2 a-1 is discovered. The observed glaciological changes can be correlated with changes in the climatic conditions and the strong El Niño event in 2015/16 is most likely the reason for the high ice loss rates in the period 2013-2016. Run off from the glaciated areas is a important water resource for large regions in Peru and Bolivia and our measurements provide crucial information for water resource management and glacier change projections. [ABSTRACT FROM AUTHOR]