A Southern Hemispheric Perspective on Holocene Climate Variability Based on Mountain Glacial Chronologies

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Mountain glaciers respond sensitively to changes in Earth's atmosphere such that records of their history serve as a useful proxy for past climates. Thus, comprehensive records of glacier extents can be combined with other types of climate archives to provide a perspective from the past on the present controls on the climate system. This project will build on recent observations by the researchers, who found that glacier-climate histories at the southern tip of South America showed different patterns from those observed in North America and Europe. Based on these observations, this research will examine recent variability in glaciers and climates along middle to high latitudinal gradients in the Southern Hemisphere, which can be used to test hypotheses regarding factors that controlled glacier activities prior to instrumental records of climate. Thus, this perspective of glacier sensitivity to past climate changes will help improve our understanding of present and projected climate changes. The researchers will collaborate with scientists from Chile and Argentina, bringing together international expertise to accomplish the research goals, which may inform regional and global societal implications for water and hydroelectric resources and local cultural significance. The team will include both undergraduate and graduate students, including collaboration with a graduate student from the Medill School of Journalism who will join the field research to produce a media package that will be of broad public interest. The researchers will also engage K-12 science teachers and their students through the Earth2Class program.This research will test hypotheses that will illuminate the spatial and temporal variability of paleoclimate signals and the interaction of polar and non-polar controls on regional and global climates. The project will determine how past variability in glaciers and climate varied along latitude in the Southern Hemisphere. Specifically, the project will: 1) map glacial features and collect samples from at least three sites in South America; 2) employ 14-C and state-of-the-art 10-Be dating on landforms as young as the historical record (to test reliability), 3) collaborate with climate-glacier modeling experts to reconstruct equilibrium line altitudes and back out the causal temperature and precipitation changes; 4) collaborate with a global climate modeler to provide insight into possible regional and hemispherical forcings, and 5) integrate findings into larger interdisciplinary efforts. This multi-faceted approach will improve understanding of temporal and spatial variability, sensitivity and response of glaciers to past climate changes. This understanding of the history of glacier responses to climate change will provide perspective on our understanding of present changes, and provide test data sets for global climate models.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.