Use of the ELA as a practical method of monitoring glacier response to climate in New Zealand’s Southern Alps

Abstract

AbstractIn lieu of direct glacier surface mass-balance measurements, equilibrium-line altitudes (ELAs) have been measured over a 28 year period at 50 selected glaciers distributed along the glacierized length of New Zealand’s Southern Alps. Analysis of the data shows that ELAs are a useful measurement of glacier response to annual climate fluctuations, although there is much variability in the degree of response between glaciers in any given year. Comparisons of individual glacier annual ELA with the mean for all annual ELAs of the Southern Alps show a large variation of individual glacier response, with coefficients of variation (r2) ranging from 0.53 to 0.90. The ELA data show detailed, but qualitative, annual mass-balance variations on both regional and individual glacier scales. The ELA record closely predicts glacier termini responses that follow after appropriate response time delays. The recorded variability in climate response for the Southern Alps suggests no single glacier is truly representative for detailed studies of glacier-climate relationships, and that a large number of ELA measurements may be as good an indicator of climate as a few mass-balance measurements. Given the appropriate mass-balance gradient, mass-balance values may be calculated for any of the monitored glaciers.