The state of rock debris covering Earth’s glaciers

Abstract

Rock debris can accumulate on glacier surfaces and dramatically reduce glacier melt. The structure of a debris cover is unique to each glacier and sensitive to climate. Despite this, debris cover has been omitted from global glacier models and forecasts of their response to a changing climate. Fundamental to resolving these omissions is a global map of debris cover and an estimate of its future spatial evolution. Here we use Landsat imagery and a detailed correction to the Randolph Glacier Inventory to show that 7.3% of mountain glacier area is debris-covered and over half of Earth’s debris is concentrated in three regions, Alaska (38.6% of total debris-covered area), Southwest Asia (12.6%) and Greenland (12.0%). We use a set of new metrics including stage, the current position of a glacier on its trajectory towards reaching its spatial debris cover carrying capacity, to quantify the state of glaciers. Debris cover is present on 44% of Earth’s glaciers and prominent (>1.0 km2) on 15%. 20% of Earth’s glaciers have a substantial percentage of debris cover for which net stage is 36% and the bulk of individual glaciers have evolved beyond an optimal moraine configuration favorable for debris cover expansion. Use of this dataset in global scale models will enable improved estimates of melt over 10.6% of the global glacier domain.

Sam Herreid

שמואל הריד

My research interests include rock debris on glaciers, advancing regional to global scale glacier modeling and restructuring the financing of climate science.