|The paper is available on the Nature Geoscience website and also here:|
|Download here some slides illustrating the paper. If you do not fall asleep before the end, you may better understand why a sampling restricted to the centerline of the glacier main trunk lead to overestimated ice losses.|
Over the last 50 years, retreating glaciers and ice caps (GIC) contributed 0.5 mm/yr to sea-level rise (SLR), and one third is believed to originate from ice masses bordering the Gulf of Alaska. However, these estimates of ice wastage in Alaska are based on methods that measure a limited number of glaciers and extrapolate the results to estimate ice loss for the many thousands of others. How these methods capture the complex pattern of decadal elevation changes at the scale of individual glacier and mountain range is unclear. Here, combining a comprehensive glacier inventory with elevation changes derived from sequential digital elevation models (DEMs), we found that, between 1962 and 2006, Alaskan glaciers lost 41.9 ± 8.6 km**3/yr water equivalent (w.e.) and contributed 0.12±0.02 mm/yr to SLR. Our ice loss is 34% lower than previous estimates. Reasons for our lower values include the higher spatial resolution of our glacier inventory and the reduction of ice thinning under debris and at the glacier margins which were not resolved in earlier work. Estimates of mass loss from GIC in other mountain regions could be subject to similar revisions.
Animation showing the retreat and thinning of Columbia glacier between 1980 and 2007. The same animation in higher resolution here.