Improving temperature reconstructions from ice-core water-isotope records

• Main Authors: Markle, Bradley R., Steig, Eric J.
• Format: Text
• Language: English
• Published: 2021
• Subjects: Antarctic; West Antarctica; Antarc*; Antarctica; ice core
• Online Access: https://doi.org/10.5194/cp-2021-37; https://cp.copernicus.org/preprints/cp-2021-37/

Oxygen and hydrogen isotope ratios in polar precipitation are widely used as proxies for local temperature. Used in combination, oxygen and hydrogen isotope ratios also provide information on sea surface temperature at the oceanic moisture source locations where polar precipitation originates. Temperature reconstructions obtained from ice core records generally rely on linear approximations of the relationships among local temperature, source temperature and water-isotope values. However, there are important nonlinearities that significantly affect such reconstructions, particularly for source-region temperatures. Here, we describe a temperature reconstruction method that accounts for these nonlinearities. We provide new reconstructions of absolute surface temperature, condensation temperature, and source-region evaporation temperature for all long Antarctic ice-core records for which the necessary data are available. We also provide thorough uncertainty estimates on all temperature histories. Our reconstructions constrain the pattern and magnitude of polar amplification in the past and reveal asymmetries in the temperature histories of East and West Antarctica.