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

Thorsten Seehaus,Philipp Malz,Christian Sommer,Matthias Braun,Antoine Rabatel,Alvaro Soruco

doi:10.1017/jog.2019.94

Abstract

AbstractClimate change has led to a significant shrinkage of glaciers in the Tropical Andes during the last decades. Recent multi-temporal quantifications of ice mass loss at mountain range to regional scale are missing. However, this is fundamental information for future water resource planning and glacier change projections. In this study, we measure temporally consistent glacier area changes and geodetic mass balances throughout the Bolivian Cordillera Real and Tres Cruces based on multi-sensor remote-sensing data. By analyzing multi-spectral satellite images and interferometric SAR data, a glacier recession of 81 ± 18 km2 (29%; 5.1 ± 1.1 km2 a−1), a geodetic mass balance of −403 ± 78 kg m−2 a−1 and a total ice mass loss of 1.8 ± 0.5 Gt is derived for 2000–2016. In the period 2013–2016, ice mass loss was 21% above the average rate. A retreat rate of 15 ± 5 km2 a−1 and a mass budget of −487 ± 349 kg m−2 a−1 are found in this more recent period. These higher change rates can be attributed to the strong El Niño event in 2015/16. The analyses of individual glacier changes and topographic variables confirmed the dependency of the mass budget and glacier recession on glacier aspect and median elevation.

Highlights

Glaciers and ice caps outside of the polar ice sheets are defined as essential climate variables by the Global Climate Observing System (GCOS) and key indicators for climate change by the Intergovernmental Panel on Climate Change (IPCC, 2014)
In the Cordillera Real, the glacier area shrunk from 244 km2 in 2000 to 175 km2 in 2016 (−28%) and in Tres Cruces from 37 km2 in 2000 to 24 km2 in 2016 (−34%)
The results presented in this study clearly indicate the rapid glacier shrinkage in Bolivia

Summary

Introduction

Glaciers and ice caps outside of the polar ice sheets are defined as essential climate variables by the Global Climate Observing System (GCOS) and key indicators for climate change by the Intergovernmental Panel on Climate Change (IPCC, 2014). Small changes in temperature and precipitation strongly influence the mass balance of tropical glaciers since they are close to melting conditions throughout the year (Francou and others, 2003; Vuille and others, 2008). The decadal precipitation variability appears larger than the long-term trend, which is regionally contrasted. Between 1939 and 2006, Vuille and others (2008) documented a near-surface air temperature increase of 0.68 °C for the Tropical Andes (1°N to 23°S), which agrees with local observations by other studies As a consequence of the changes in climatic conditions, the equilibrium line altitude (ELA) of the glaciers in this region rose (Rabatel and others, 2013; Réveillet and others, 2015). At the Quelccaya Ice Cap, Peru, an ELA shift from 5275 to 5414 m a.s.l. between 1975 and 2012 was observed by Hanshaw and Bookhagen (2014), and at Zongo Glacier, Bolivia, a temperature sensitivity of the ELA of 150 ± 30 m °C−1 was estimated (Lejeune, 2009)

Results

Discussion

Conclusion