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Glacier mass balance measurements help to provide an understanding of the behavior of glaciers and their response to local and regional climate influences. In 2005, the United States Geological Survey established a surface mass balance monitoring program on Sperry Glacier, Montana, USA. This program is the first quantitative study of mass changes of a glacier in this region and continues to the present. This paper describes the methods used during the first eleven years of measurements and reports the associated results. Between years 2005-2015, we estimate Sperry Glacier lost approximately 4.37 m of water equivalent averaged over its entire area. The mean winter, summer, and annual glacier-wide mass balances were 2.92 m per year, -3.41 m per year, and -0.40 m per year respectively. We derive these cumulative and mean results from an expansive dataset of snow depth, snow density, and ablation measurements taken at selected points on the glacier, the resultant mass balance point values for these measurement sites, and a time series of seasonal and annual glacier-wide mass balances for all eleven measurement years. We also provide measurements of total glacier surface and accumulation areas for select years. All data have been submitted to the World Glacier Monitoring Service and are available at http://dx.doi.org/10.5904/wgms-fog-2016-08http://dx.doi.org/10.5904/wgms-fog-2016-08. This foundational data enhances our basic understanding of mass balance of Sperry Glacier, and future work will focus on the processes that control accumulation and ablation patterns across the glacier. [ABSTRACT FROM AUTHOR]

Abstract: The interpretation of climate change based on the behavior of small cirque glaciers is not always straightforward or unique. In this study of Sperry Glacier, Glacier National Park, Montana, we model future change of the glacier under 11 different warming scenarios. The scenarios vary from no warming from present conditions to warming at a linear rate of 10°C/century. We assume constant precipitation and only consider change invoked by warming. Our cellular automata model is based on simple rules that account for mass balance gradient, aspect, avalanching, and the flow of ice to redistribute mass. We constrain the model with glaciological data including georadar-measured ice depth, field-measured surface mass balance, and field-mapped ice surface topography. Under the most probable temperature increase based on downscaled OA-GCM output for the IPCC A1B scenario, we conservatively estimate the glacier persisting through at least 2080. By comparing glacier volume responses to different warming scenarios we elucidate a relationship between the magnitude of temperature change and the sensitivity of the glacier to small variations in the temperature increase. We find that the greater the magnitude of the temperature increase, the less sensitive the glacier area and volume become to slight differences in the warming rate. If we generalize this relationship to the region, we expect that a small change in climate will produce varying responses for glaciers throughout the region, whereas the glacier response to a large change in climate will likely be very similar over the entire region. [ABSTRACT FROM AUTHOR]