Contribution of Alaskan glaciers to sea-level rise derived from satellite imagery

• Published in: Nature geoscience Vol. 3; no. 2; pp. 92 - 95
• Main Authors: Berthier, E., Schiefer, E., Clarke, G. K. C., Menounos, B., Rémy, F.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2010; Nature Publishing Group
• Subjects: 704/106/125; Earth and Environmental Science; Earth Sciences; Earth System Sciences; Geochemistry; Geology; Geophysics/Geodesy; Glacial drift; Glaciers; Ice caps; letter; Mountain regions; Oceanography; Sciences of the Universe; Sea level; Alaska; Sea level rise; satellite; Glacier; SPOT5; ASTER
• ISSN: 1752-0894; 1752-0908
• DOI: 10.1038/ngeo737

Over the past 50 years, retreating glaciers and ice caps have contributed 0.5 mm yr −1 to sea-level rise, and one third of this contribution is believed to come from ice masses bordering the Gulf of Alaska. A combination of a comprehensive glacier inventory with high-resolution elevation data indicates that the ice loss from Alaskan glaciers is 34% less than previously thought. Over the past 50 years, retreating glaciers and ice caps contributed 0.5 mm yr −1 to sea-level rise 1 , and one third of this contribution is believed to come from ice masses bordering the Gulf of Alaska 2 , 3 . However, these estimates of ice loss in Alaska are based on measurements of a limited number of glaciers that are extrapolated to constrain ice wastage in the many thousands of others. Uncertainties in these estimates arise, for example, from the complex pattern of decadal elevation changes at the scale of individual glaciers and mountain ranges 4 , 5 , 6 , 7 . Here we combine a comprehensive glacier inventory with elevation changes derived from sequential digital elevation models. We find that between 1962 and 2006, Alaskan glaciers lost 41.9±8.6 km 3  yr −1 of water, and contributed 0.12±0.02 mm yr −1 to sea-level rise, 34% less than estimated earlier 2 , 3 . Reasons for our lower values include the higher spatial resolution of our glacier inventory as well as the reduction of ice thinning underneath debris and at the glacier margins, which were not resolved in earlier work. We suggest that estimates of mass loss from glaciers and ice caps in other mountain regions could be subject to similar revisions.