PhD thesis defence by Christian Holme – Københavns Universitet

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PhD thesis defence by Christian Holme

Stable water isotope variability as a proxy of past temperatures

Ice caps on Greenland and Antarctica store old precipitated snow in well-ordered ice layers. The water isotopic signature of each layer reflects past temperature conditions. This PhD dissertation investigates to what extent climate variability can be reconstructed from water isotope proxies using various methods. The work is comprised of two published papers and one submitted manuscript that each tackle this subject from a different perspective.

The first study reviews a number of diffusion-based temperature reconstruction techniques in terms of accuracy and precision. The second study examines the power spectral density of continuously measured water isotope data in order to accurately and efficiently extract past climate conditions. The third study investigates if the relationship between the water isotope variability of three Greenlandic ice cores and regional temperatures is constant back in time. Finally, the dissertation presents a preliminary temperature reconstruction from a West Antarctic ice core and discusses the implications of the results.

The defence, which is public, will begin with a presentation by the PhD candidate followed by an examination conducted by the assessment committee and questions from the audience.

Assessment committee:

  • Dr. Sune Olander Rasmussen, Associate Professor, Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Denmark
  • Dr. Anaïs Orsi, Research Scientist, Laboratoire des Sciences du Climat et de l'Environnement, Université Paris Saclay, France.
  • Dr. Carlo Barbante, Professor and Director of the Institute for the Dynamics of Environmental Processes, University Ca’Foscari, Venice, Italy.

The thesis is available from Christian Holme, christian.holme@nbi.ku.dk, upon request.
Questions about the defence can be directed to the chairman of the assessment committee, Sune Olander Rasmussen at olander@nbi.ku.dk