Reanalysis of the US Geological Survey Benchmark Glaciers: long-term insight into climate forcing of glacier mass balance

• Published in: Journal of Glaciology
• Main Authors: Shad O'Neel, Christopher McNeil, Louis C. Sass, Caitlyn Florentine, Emily H. Baker, Erich Peitzsch, Daniel McGrath, Andrew G. Fountain, Daniel Fagre
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2019
• Subjects: Arctic glaciology; glacier mass balance; mountain glaciers; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Arctic; glacier; glaciers; Journal of Glaciology; Alaska
• Online Access: https://doi.org/10.1017/jog.2019.66; https://doaj.org/article/5026b4739e954a2aa26239f1ed376db8

Mountain glaciers integrate climate processes to provide an unmatched signal of regional climate forcing. However, extracting the climate signal via intercomparison of regional glacier mass-balance records can be problematic when methods for extrapolating and calibrating direct glaciological measurements are mixed or inconsistent. To address this problem, we reanalyzed and compared long-term mass-balance records from the US Geological Survey Benchmark Glaciers. These five glaciers span maritime and continental climate regimes of the western United States and Alaska. Each glacier exhibits cumulative mass loss since the mid-20th century, with average rates ranging from −0.58 to −0.30 m w.e. a−1. We produced a set of solutions using different extrapolation and calibration methods to inform uncertainty estimates, which range from 0.22 to 0.44 m w.e. a−1. Mass losses are primarily driven by increasing summer warming. Continentality exerts a stronger control on mass loss than latitude. Similar to elevation, topographic shading, snow redistribution and glacier surface features often exert important mass-balance controls. The reanalysis underscores the value of geodetic calibration to resolve mass-balance magnitude, as well as the irreplaceable value of direct measurements in contributing to the process-based understanding of glacier mass balance.