Preprints
https://doi.org/10.5194/cp-2021-37
https://doi.org/10.5194/cp-2021-37

  12 Apr 2021

12 Apr 2021

Review status: this preprint is currently under review for the journal CP.

Improving temperature reconstructions from ice-core water-isotope records

Bradley R. Markle1,2,3 and Eric J. Steig3 Bradley R. Markle and Eric J. Steig
  • 1Institute of Arctic and Alpine Research, University of Colorado, Boulder
  • 2Department of Geological Sciences, University of Colorado, Boulder
  • 3Department of Earth and Space Sciences, University of Washington

Abstract. 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.

Bradley R. Markle and Eric J. Steig

Status: open (until 04 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on cp-2021-37', Robert Hellmann, 15 Apr 2021 reply

Bradley R. Markle and Eric J. Steig

Bradley R. Markle and Eric J. Steig

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Short summary
The geochemistry preserved in polar ice can provide detailed histories of Earth’s climate over millennia. Here we use the stable isotope ratios of ice form many Antarctic ice cores to reconstruct temperature variability of Antarctica and of the midlatitude Southern Hemisphere over tens of thousands of years. We improve upon existing methods to estimate temperature from the geochemical measurements and investigate the patterns of climate change in the past.