A Northern Hemisphere Holocene Paleoatmospheric Record of Ethane and Acetylene from the GISP2 Ice Core

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Biomass burning has a major impact on atmospheric composition and climate due to emissions of greenhouse gases and aerosols. The past history of fire emissions is not well documented, and as a result, the relationship between fire and climate on long time scales is not well understood. This project will investigate the atmospheric histories of ethane and acetylene, trace gases emitted to the atmosphere from biomass and biofuel burning. Measurements of these trace gases in the air bubbles entrapped in Greenland ice cores will document past variations in the atmospheric levels of these trace gases over a wide range of climatic conditions and environmental change. The data will provide new insight into the variability in fire on millennial time scales and quantify the contribution of fire to past atmospheric levels of greenhouse gases. This knowledge will contribute to the development of land surface and earth system models capable of simulating fire in future climate scenarios. This project will support the dissertation research of a PhD student in the UC Irvine Department of Earth System Science and outreach activities in K-12 classrooms through the non-profit CLEAN Education initiative founded and operated by graduate students at UC Irvine. Ethane and acetylene measurements in firn air and shallow ice cores demonstrate that the entrapped air in polar ice contains a paleoatmospheric record of these trace gases. In this study, the investigators will analyze ethane and acetylene in ice core samples from the GISP2 ice core (Summit, Greenland), spanning the last glacial maximum, glacial/interglacial transition, and Holocene periods. Trace gas emissions will be inferred from the atmospheric histories using a 3-D global photochemical/transport model and biogeochemical box models. This study will provide a northern hemispheric counterpart to an Antarctic ice core record under development. Together, the Greenland and Antarctic records will provide estimates of: 1) past global biomass burning emissions of these trace gases, 2) partitioning of fire emissions between tropical and boreal sources, and 3) the magnitude and variability of pyrogenic methane emissions.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.