Assessing topographic impacts on tropical glacier extent and moraine formation

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Many mountain glaciers are currently retreating as a result of climate change, and decades of research have used past glacial fluctuations (advances and retreats) to understand the mechanisms of past climate change. Yet, mountain glaciers are also influenced by underlying topography (e.g., the mountain height above a glacier and valley slope beneath a glacier). This project examines the influence of topography on glacial extents using computer modeling in conjunction with reconstructions of past glacial extents in mountain ranges in Uganda and Colombia. The small footprint of these tropical mountain ranges makes it likely that neighboring valleys experience similar climate conditions and, thus, any differences in glacial extents should be due to topographic differences among the valleys. Moreover, Uganda and Colombia are among the few tropical locations where long-term records of glacial changes in multiple adjacent valleys may be obtained. The project will improve the ability to forecast future glacial changes and model landscape evolution. It will also advance the use of past glacial extents to understand the causes of past climate changes. The project supports an international tropical glacier workshop and the development of high school STEM activities that aim to broaden participation of underrepresented groups. It also supports two early career female researchers in a domain of science where women remain highly underrepresented.The project will use glacial modeling in combination with modern climate data and surface exposure dating of glacial moraines (ridges that mark former glacial extents) to assess topographic impacts on tropical glacial extents and moraine formation. It has the following two objectives: 1) assess how variations in specific topographic characteristics influence glacial extents using glacial modeling with idealized digital elevation models; and 2) assess how variations in topography influenced past glacial extents in two tropical mountain ranges (the Rwenzori Mountains in Uganda and the Sierra Nevada del Cocuy in Colombia) using glacial modeling and surface exposure dating of moraines. The project will provide one of the few datasets available to examine the relative impacts of climate and topography on glacial extents and, thus, advance the ability to model the response of glaciers to future climate changes. It will also improve the ability to infer past climate conditions from the geomorphic record of glacial extents.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.