Collaborative Research: P2C2--ICECAP (ICE age Chemistry And Proxies) Phase-4: Studying Aerosol Transport, Forcing, and Climate Feedbacks during the Common and Last Glacial Eras

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).The research team generally aims to develop a more complete and quantitative understanding of (1) natural and anthropogenic drivers of biomass burning, and (2) linkages between Northern Hemisphere (NH) biomass burning and climate over the most recent 2,000 years and rapid climate change during five Dansgaard-Oeschger (D-O) events of the last glacial era. To accomplish these goals, the research team will make new measurements on already-archived ice core samples and leverage from existing published and unpublished ice core data as well as interpret findings within a model framework, including simulations with both simple models and the more detailed, 3-D ICECAP model.The research team will develop an Arctic ice core array of biomass burning tracer deposition spanning the last 2,000 years from thirteen ice core sites—including new measurements on an archived ice core from the northernmost ice cap of Greenland— to quantify how biomass burning emissions have changed over the past two millennia. This detailed array, which incorporates ice core sites representative of burning in Europe, North America, and Siberia, will aid in the assessment of how biomass burning has changed regionally across the high latitude NH. In addition, the researchers will use ICECAP, which includes an atmospheric chemistry transport component (GEOS-Chem) and a dynamic vegetation and fire model (LPJ-LMfire), to explore links between biomass burning, human activities, and climate variability, as well as to assess the impact of fire emissions on radiative forcing and chemistry-climate interactions.Wildfires are a critical component of the earth system. Biomass burning emissions play an important role in climate through both direct and indirect radiative forcing and fire-driven land cover change alters albedo and the hydrologic cycle. Current model simulations, however, are hampered by uncertainties associated with natural and anthropogenic aerosol emission sources, especially during the preindustrial era which serves as the baseline for assessment of modern forcing. It is increasingly recognized that humans have altered atmospheric aerosols much earlier than the commonly-used preindustrial baseline of 1750 CE; this project will help improve model parameterization of preindustrial aerosol transport and emissions, including from both anthropogenic and natural sources, as well as of aerosol-climate interactions and feedbacks across rapid climate change during the last glacial era.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.