Benchmarking Spatial Patterns of Glacier Change

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This research will investigate global patterns of past glacier advance and retreat to analyze regional patterns of environmental variability. During times of global glacier recession, glaciers in different parts of the world behaved differently. The rate of glacier retreat varied through time, and in some cases, glacier retreat was interrupted by short intervals of glacier growth. These differential spatial patterns can help scientists predict future patterns of regional response to global environmental variability. In this project, using various earth science techniques, investigators will analyze glacial landforms in Alaska to affirm regional differences in rates of past glacier change. Alaska is a region where past glacier change is less well understood than other parts of the world, but one where regional glacier change was different from global patterns. Findings will contribute to an improved understanding of past regional environmental variability and thereby be an important data source for future modelling. The project's broader impacts include the career advancement of a scientist from an underrepresented group and includes the training of graduate and undergraduate students. Dissemination will include academic publications and public-oriented materials disseminated via national parks and native communities in Alaska. To better understand the trajectory of future glacier change, and related environmental variability, better regional influences on glacier behavior across the planet must be elucidated. For this reason, detailed knowledge of regional glacier change and their deviations from the global pattern are critically needed for paleoclimate and glacial-geomorphology communities. Carbon dioxide changes during the last deglaciation were tightly coupled to mountain glacier change. Yet, this compilation lacked data from the high latitudes. Recent research hypothesizes that carbon dioxide in modern times has overwhelmed regional drivers and has become the dominant control on glacier change. The proposed research aims address these ideas by filling in a key data gap. The investigators will test two hypotheses that are at the forefront of paleoclimate and glacier science. (1) Atmospheric carbon dioxide is the primary forcing mechanism of mountain glacier change. (2) Glaciers outside the North Atlantic region advanced during Heinrich stadials, but retreated prior to their terminations. The researchers will reconstruct a highly detailed mountain glacier record from the high northern latitudes, temporally spanning from the last deglaciation to the present. Because continental ice sheets covered most of the high northern latitudes during Ice Ages, there are few accessible sites that offer detailed glacier moraine sequences with materials that can be precisely dated. Because Alaska remained largely untouched by continental sheets during the last glacial period and was instead dominated by mountain glaciers, this is an ideal location to benchmark and develop a record of glacier change since last deglaciation. The PIs will combine cosmogenic Beryllium-10 dating of an exceptional moraine sequence in the Revelation Mountains in western Alaska with digital mapping and glacier equilibrium-line altitude analysis to test their hypotheses and to benchmark a regional record of mountain glacier change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.