Climate sensitivity and mass-balance evolution of Gran Campo Nevado ice cap, southwest Patagonia

Abstract

A degree-day model extended for surface mass-balance calculations has been applied to derive the sensitivity of Gran Campo Nevado ice cap (GCN), southwest Patagonia, to climate change. Seasonal sensitivity characteristics were computed using automatic weather station data gathered in the period 2000-05. Results indicate pronounced mass-balance sensitivity to temperature during the summer, with monthly values of -0.27 ± 0.01 m w.e. K-1. Monthly sensitivity to a 10% precipitation perturbation fluctuates around +0.03 m w.e. The sensitivity characteristics obtained were used to model the surface mass-balance evolution of GCN during the 20th and 21st centuries based on monthly means of air temperature and precipitation derived from bias-corrected weather station data and statistically downscaled re-analysis and general climate model data. Surface mass balance shows a persistently negative trend ranging from around +1 m w.e. a-1 at the beginning of the 20th century down to almost -1.5 m w.e. a-l during the first years of the 21st century, with only a few positive years occurring occasionally during the second half of the 20th century. The scenario for the end of the 21st century totals approximately -4.5 m w.e. a-1, i.e. an estimated ice volume loss for GCN of 59 km3 during 1900-2099.