P2C2: New Analyses of Paleo-Seasonality and Climate Variability Using Fossil Wood

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This project aims to leverage existing fossil wood specimens and a newly developed model to generate new data on seasonality and climate variability across three field sites: 1) Banks Island, Arctic Canada (early Eocene); 2) Nanning Basin, China (late Oligocene); and 3) Finish Stream, Siberia (late Miocene). More than 100 fossil specimens are available from previous collections at these sites. Preliminary data show sufficient cellulose preserved in these fossils is suitable for high-resolution oxygen isotope analysis. These new data, combined with published carbon isotope records, allow for new quantitative estimates of a full suite of seasonal climate parameters (summer precipitation, winter precipitation, cold month mean temperature, warm month mean temperature) at annual resolution. Such data will allow for changes in seasonality to be assessed across multiple levels of atmospheric carbon dioxide (CO2) concentrations for both Arctic and monsoon climates. The researchers plan to generate new high-resolution stable isotope datasets to test: 1) inter-annual variability in the East Asian Monsoon during the late Oligocene, when atmospheric CO2 concentrations were similar to projected late 21st century levels, and 2) how winter versus summer temperatures change with increases in mean annual temperature, across both subtropical and Arctic environments. Recent modeling work predicts changes in precipitation timing and intensity occur under warmer mean annual temperatures, and greater wintertime versus summertime warming, which is amplified in Arctic environments; however, proxies generally lack suitable resolution to test these hypotheses in the fossil record.The potential Broader Impacts include new paleoclimate records at sub-annual resolution during the Eocene, Oligocene and Miocene. These high-resolution proxies are rare and will provide new information about inter-annual climate variability and seasonality at high and low latitudes during time intervals with different atmospheric CO2 concentration. Such data will benefit proxy and modeling paleoclimate communities. The project will support one PhD and one undergraduate student as well as researchers at various career-stages.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.