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Hypsometric control on glacier mass balance sensitivity in Alaska and northwest Canada

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Full Publication: http://dx.doi.org/10.1002/2016EF000479

Product Type: Journal Article

Year: 2017

Authors: McGrath, D., L. C. Sass, S. R. O'Neel, A. A. Arendt, and C. Kienholz


Suggested Citation:
McGrath, D., L. C. Sass, S. R. O'Neel, A. A. Arendt, and C. Kienholz. 2017. Hypsometric control on glacier mass balance sensitivity in Alaska and northwest Canada. Earth's Future 5(3):324-336. doi:10.1002/2016EF000479

Abstract


Glacier hypsometry provides a first-order approach for assessing a glacier's response to climate forcings. We couple the Randolph Glacier Inventory (RGI) to a suite of in situ observations and climate model output to examine potential change for the ~27,000 glaciers in Alaska and northwest Canada through the end of the 21st century. By 2100, based on RCP 4.5 to 8.5 forcings, summer temperatures are predicted to increase between +2.1 and +4.6° C, while solid precipitation (snow) is predicted to decrease by -6 to -11%, despite a +9 to +21% increase in total precipitation. Snow is predicted to undergo a pronounced decrease in the fall, shifting the start of the accumulation season back by ~1 month. In response to these forcings, the regional equilibrium line altitude (ELA) may increase by +105 to +225 m by 2100. The sensitivity to this increase is highly variable, with the most substantive impact for glaciers with either limited elevation ranges (often small (<1 km2) glaciers, which account for 80% of glaciers in the region) or those with top-heavy geometries, like icefields. For more than 20% of glaciers, future ELAs, given RCP 6.0 forcings, will exceed the maximum elevation of the glacier, resulting in their eventual demise, while for others, accumulation area ratios (AAR) will decrease by >60%. Our results highlight the first-order control of glacier hypsometry on individual glacier response to climate change, and the variability that hypsometry introduces to a regional response to a coherent climate perturbation.

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