Changes of the tropical glaciers throughout Peru between 2000 and 2016 – mass balance and area fluctuations

Abstract

Abstract. 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 km2 (−29 %, −34.3 km2 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 km2 (−16 %, −101.9 km2 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.

60 Years of Glacier Elevation and Mass Changes in the Maipo River Basin, Central Andes of Chile

“…Photographs taken four days before the TanDEM-X acquisition show the glacier surface comprising bare ice~4600 m a.s.l (Supplementary Figure S1). However, for consistency with other studies regarding uncertainty assessment using TanDEM-X over the Andes [4,40], we applied a similar procedure as Braun et al [4], who assumed a linear increase of radar signal penetration (V pen ) difference from 0 m up to 5 m at the maximum elevation of the study region, which is integrated over the area above the Equilibrium Line Altitude (ELA) to obtain (V pen ), in this case,~4000 m a.s.l [15].…”

“…The DLR provides InSAR image pairs as co-registered single-look complex images in HH polarization. We processed multiple along-track TanDEM-X scenes acquired on the same day, which are concatenated and processed using differential SAR interferometry (DInSAR) with SRTM C-band DEM as a reference (e.g., [4,40]) ( Figure 2). The topographic phase is simulated from SRTM DEM using the TanDEM-X interferometric parameter to obtain a differential interferogram.…”

Mass balance and area changes of glaciers in the Cordillera Real and Tres Cruces, Bolivia, between 2000 and 2016

“…In the time interval 2013–2016, we obtained an enhancement of the retreat rates toward 15 ± 5 km 2 a −1 in our study area. A similar area change trend was observed at Peruvian glaciers by Seehaus and others (2019). The increased rates are comparable to the finding of Cook and others (2016) in the period 1986–1992 (14.5 km 2 a −1 ).…”

“…Higher average temperatures are obtained for the period 2013–2016, as compared to the period 2000–2013, and a clear peak in the temperature trend is obvious during the El Niño event in 2015/16. Thus, it is likely that our observed increase glacier shrinkage in the period 2013–2016, which is also reported by Seehaus and others (2019) for Peruvian glaciers, can be attributed to the strong El Niño event in 2015/16. Since the response time of tropical glaciers to mass-balance variations is very short (e.g.…”

“…The increased rates are comparable to the finding of Cook and others (2016) in the period 1986–1992 (14.5 km 2 a −1 ). These high retreat rates are most likely to be associated with the strong El Niño events that occurred during these two observation periods (see Section 5.3 and Seehaus and others (2019) for more details).…”