The Queens College School of Earth and Environmental Sciences presents Stephen Pekar from QC SEES: “Ice-Volume Changes During Times of Elevated Atmospheric CO2 : Looking Back to our Future.”


Past climatic changes and the resulting changes in sea level / glacial ice volume have become of particular interest as rising atmospheric greenhouse gases owing to anthropogenic input have increased to levels not observed since before Homo sapiens roamed this Earth. Considerable improvements have been made in deciphering past sea-level / ice-volume changes, such as using backstripped stratigraphy from passive margins and geochemical proxies. In addition, the advent of new proxies for estimating paleo CO2 levels permit a better comparison between past greenhouse gas levels and climate and ice-volume changes. For example, during the last time that CO2 was higher than today, the Middle Miocene Climatic Optimum (MMCO, 15-16 Ma), sea level at least 30 meters higher than modern. While these records provide a convincing story of how greenhouse gases and climate are coupled throughout the Cenozoic, using them to predict about future climate changes are not as straight forward. The most obvious caveat is differences in time scale; while today’s changes are being measured at the decadal or century scale, nearly all paleo records contain resolutions in the thousands of years. In addition, the further back in time, differences in continental configuration and oceanic circulation would become more pronounced. Nevertheless, taking into consideration these caveats, paleom climate records can provide insights to what our planet was like under elevated CO2 conditions and can serve as possible predictors if not for decadal but for the centuries to millennial times scales.


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