Projected increases in surface melt and ice loss for the Northern and Southern Patagonian Icefields

Claudio Bravo,Andrew N Ross,Deniz Bozkurt,Duncan J Quincey

doi:10.1038/s41598-021-95725-w

Abstract

The Northern Patagonian Icefield (NPI) and the Southern Patagonian Icefield (SPI) have increased their ice mass loss in recent decades. In view of the impacts of glacier shrinkage in Patagonia, an assessment of the potential future surface mass balance (SMB) of the icefields is critical. We seek to provide this assessment by modelling the SMB between 1976 and 2050 for both icefields, using regional climate model data (RegCM4.6) and a range of emission scenarios. For the NPI, reductions between 1.5 m w.e. (RCP2.6) and 1.9 m w.e. (RCP8.5) were estimated in the mean SMB during the period 2005–2050 compared to the historical period (1976–2005). For the SPI, the estimated reductions were between 1.1 m w.e. (RCP2.6) and 1.5 m w.e. (RCP8.5). Recently frontal ablation estimates suggest that mean SMB in the SPI is positively biased by 1.5 m w.e., probably due to accumulation overestimation. If it is assumed that frontal ablation rates of the recent past will continue, ice loss and sea-level rise contribution will increase. The trend towards lower SMB is mostly explained by an increase in surface melt. Positive ice loss feedbacks linked to increasing in meltwater availability are expected for calving glaciers.

Highlights

The Northern Patagonian Icefield (NPI) and the Southern Patagonian Icefield (SPI) have increased their ice mass loss in recent decades
The mean surface mass balance (SMB) was negative in the NPI, reaching an annual mean value of − 0.6 ± 2.1 m w.e. yr−1, in agreement with previously published geodetic mass balances in comparable periods[3,4,6,8,9,10,11,12] (Fig. 2a, Table S2) and with previously modelled SMBs
For the NPI a mean reduction between 1.5 and 1.9 m w.e. was projected for the scenarios RCP2.6 and RCP8.5 respectively, while in SPI the reduction was within the range of 1.1 and 1.5 m w.e

Summary

Introduction

The Northern Patagonian Icefield (NPI) and the Southern Patagonian Icefield (SPI) have increased their ice mass loss in recent decades. The glaciers of the Southern Andes represent one of the highest contributors, responsible for a total of 3.3 mm of sea-level rise between 1961 and 20162 This region includes two large temperate icefields: the Northern Patagonian Icefield (NPI) and the Southern Patagonian Icefield (SPI) (Fig. 1). The Patagonian Icefields represent 83% of the total ice loss in the Southern Andes[10] and it has been estimated that the sea-level contribution of Patagonian glaciers in the last 50 years is one order of magnitude larger than at the Little Ice Age (LIA) maximum, dated AD1650 in the SPI and AD1870 in the NPI13.

Objectives

Results

Discussion

Conclusion