P2C2: Collaborative Research: Timing of the Glacial Termination in Southernmost South America

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Climate change is one of the most pressing societal issues of our time, with implications for human health and welfare, the economy, and national security. Improved projections of future climate rely on more detailed understanding of the mechanisms driving Earth’s climate system, which can often be illuminated from the perspective of geological records of past climates. The research funded by this award will examine the largest global warming event in the recent geological past: the transition from the last ice age to the present interglacial world. First, a climate record will be produced by documenting the age and location of landforms left by rapidly retreating glaciers at the end of the last ice age. These records will then be used, along with computer models, to test hypotheses about different components of the climate system that are thought to play important roles in rapid warming of Earth. Such information will improve understanding of how Earth’s climate system operates and inform models used for climate prediction. This detailed understanding of Earth's climate system may help policy makers to articulate climate policies that will provide multiple societal benefits. The researchers will also educate young scientists in STEM fields, thereby increasing the STEM workforce, which is in the national interest. This award will also will support the education of a science journalism student, who will be trained to communicate the science results to the public, providing long-term benefits of public awareness and understanding of global change science.Despite significant progress, the origin of ice-age terminations remains unresolved. At the core of this issue is the precise inter- and intra-hemispheric timing of the end of the ice age, because such information yields clues as to the mechanisms that underlie the termination. The research team will test the hypothesis that the temperature rise of the last termination in southern latitudes was earlier and faster than previously recognized, so fast that it may require a major overhaul of existing hypotheses. The research project will use detailed radiocarbon and exposure dating of glacial landforms, along with glaciological modeling, to document the timing and magnitude of the termination of the Cordillera Darwin icefield, in southernmost South America. These data will be integrated with existing paleoclimate records at lower latitudes with the GFDL Earth System Model 2M to assess the feasibility of various forcing factors for the termination, such as an ocean bipolar seesaw, shifting of the southern hemisphere westerlies, and atmospheric carbon dioxide concentrations. This work will strengthen collaborations between US and Chilean institutions and afford mentoring and education opportunities for students. The research team will embed a science journalism graduate student in the field party, who will produce articles in a variety of media formats.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.