Projections of the future disappearance of the Quelccaya Ice Cap in the Central Andes

Christian Yarleque,Hugo Ramos,Antoine Rabatel,Oliver Elison Timm,Mathias Vuille,Douglas R Hardy,Jorge De La Cruz

doi:10.1038/s41598-018-33698-z

Abstract

We analyze the future state of Quelccaya Ice Cap (QIC), the world’s largest tropical ice cap with a summit elevation of 5680 m a.s.l., which, in terms of its elevation range (~5300–5680 m a.s.l.), is representative of many low-elevation glacierized sites in the tropical Andes. CMIP5 model projections of air temperature (Ta) at QIC indicate a warming of about 2.4 °C and 5.4 °C (respectively) for RCP4.5 and RCP8.5 scenarios by the end of the 21st century, resulting in a pronounced increase in freezing level height (FLH). The impact of this warming on the QIC was quantified using equilibrium-line altitude (ELA) projections. The change in the ELA was quantified based on an empirical ELA–FLH relationship, and calibrated with observations of the highest annual snowline altitude (SLA) derived from LANDSAT data. Results show that from the mid-2050s onwards, the ELA will be located above the QIC summit in the RCP8.5 scenario. At that time, surface mass balance at QIC and most tropical glaciers at similar elevations will become increasingly negative, leading to their eventual complete disappearance. Our analysis further corroborates that elevation-dependent warming (EDW) contributes significantly to the enhanced warming over the QIC, and that EDW at Quelccaya depends on the rate of anthropogenic forcing.

Highlights

We analyze the future state of Quelccaya Ice Cap (QIC), the world’s largest tropical ice cap with a summit elevation of 5680 m a.s.l., which, in terms of its elevation range (~5300–5680 m a.s.l.), is representative of many low-elevation glacierized sites in the tropical Andes
To verify and quantify how much the elevation-dependent warming (EDW) will affect QIC in the 21st century, we present a comparison between the ELASST and ELAatm at QIC, both bias-corrected and calculated based on equation (1), but using as input the FLHSST from equation (2), and FLHatm derived by interpolating Ta and Zg, respectively, from 16 CMIP5 models
CMIP5 model simulations of future temperature changes were applied to study the impacts of climate change over the Quelccaya Ice Cap region, assessing the relationship between equilibrium-line altitude (ELA) and freezing level height (FLH) and how these variables relate to tropical sea surface temperature (SST) forcing in the past and the future

Summary

Introduction

We analyze the future state of Quelccaya Ice Cap (QIC), the world’s largest tropical ice cap with a summit elevation of 5680 m a.s.l., which, in terms of its elevation range (~5300–5680 m a.s.l.), is representative of many low-elevation glacierized sites in the tropical Andes. CMIP5 model projections of air temperature (Ta) at QIC indicate a warming of about 2.4 °C and 5.4 °C (respectively) for RCP4.5 and RCP8.5 scenarios by the end of the 21st century, resulting in a pronounced increase in freezing level height (FLH) The impact of this warming on the QIC was quantified using equilibrium-line altitude (ELA) projections. QIC is retreating at an accelerated pace, with a shrinking of the QIC area at a rate of 0.57 ± 0.10 km[2] yr−1 over the 1980–2010 period[5] This retreat is consistent with the reduction in glacierized surface area observed throughout the tropical Andes, including in the Cordillera Blanca and the Cordillera Ampato[3,4], located to the north and south of the Cordillera Vilcanota and QIC, respectively

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Conclusion