Abstract
ABSTRACTAccurate quantification of rates of glacier mass loss is critical for managing water resources and for assessing hazards at ice-clad volcanoes, especially in arid regions like southern Peru. In these regions, glacier and snow melt are crucial dry season water resources. In order to verify previously reported rates of ice area decline at Nevado Coropuna in Peru, which are anomalously rapid for tropical glaciers, we measured changes in ice cap area using 259 Landsat images acquired from 1980 to 2014. We find that Coropuna Ice Cap is presently the most extensive ice mass in the tropics, with an area of 44.1 km2, and has been shrinking at an average area loss rate of 0.409 km2a−1(~0.71% a−1) since 1980. Our estimated rate of change is considerably lower than previous studies (1.4 km2a−1or ~2.43% a−1), but is consistent with other tropical regions, such as the Cordillera Blanca located ~850 km to the NW (~0.68% a−1). Thus, if glacier recession continues at its present rate, our results suggest that Coropuna Ice Cap will likely continue to contribute to water supply for agricultural and domestic uses until ~2120, which is nearly 100 years longer than previously predicted.
Highlights
Waxing and waning of terrestrial ice has been the hallmark of Earth’s climate system since at least the Pleistocene, recent evidence that almost all terrestrial ice bodies are presently losing mass is a concerning sign of anthropogenic climate change (Kargel, 2014)
Given the large areal extent, high elevation and difficult access of Coropuna Ice Cap, we focus on remote sensing observations to construct a multi-decadal time series of areal ice extent
Nine studies have previously attempted to quantify the glacierized area and rates of ice loss for Coropuna (Ames and others, 1988; de Silva and Francis, 1990; Nunez-Juarez and Valenzuela-Ortiz, 2001; Racoviteanu and others, 2007; Forget and others, 2008; Peduzzi and others, 2010; Úbeda, 2011; Silverio and Jaquet, 2012; Veettil and others, 2016), the results of these studies are inconsistent with each other (Fig. 2) and with what has been found at other tropical glaciers
Summary
Waxing and waning of terrestrial ice has been the hallmark of Earth’s climate system since at least the Pleistocene, recent evidence that almost all terrestrial ice bodies are presently losing mass is a concerning sign of anthropogenic climate change (Kargel, 2014). Rates of mass loss are concerning in the tropics (Kaser, 1999), where changes in glacier meltwater fluxes pose serious risks to downstream communities. As urban centers grow in the Andes, water resources are being increasingly strained by rising demand for water (Magrin and others, 2014) These compounding factors make the people of Peru vulnerable to long-term water shortages associated with glacier loss. Volcanic heat fluxes can cause increased melting and jökulhlaups through ice melting during magma recharge events (Björnsson, 1988). While these types of events are rare, quantifying upstream ice extent is important for the assessment and mitigation of potential downstream hazards
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