Niklas Kappelt

Ice cores offer us an incredible library of paleoclimate data, the key to which is accurate dating. Different methods exist and all have their own advantages and flaws. I am researching the potential of the ³⁶Cl/¹⁰Be ratio to be used a dating tool, as both isotopes are naturally occurring radionuclides and therefore decay over time. Using the ratio instead of a single isotope helps to eliminate factors influencing their production. The main issue with this method is the unknown physical and chemical behaviour of chlorine in snow and firn, which I hope to understand better in the future.

I investigate these processes by relating deposition and transport to influencing factors such as precipitation and temperature. Stable isotope fractionation measurements of ³⁵Cl and ³⁷Cl may help to better understand mobility as well as to identify and correct for loss of ³⁶Cl. Since precipitation appears to be a key influencing factor for loss, the relationship may also be exploited the other way around: chlorine has the potential to be used as a proxy for precipitation. For my research I use ice from different measurement sites both in Greenland and Antarctica, so different environmental conditions can be compared. While the behaviour of chlorine, I also directly evaluate the ³⁶Cl/¹⁰Be ratio as a dating method by measuring it in ice of known age and comparing the prediction with reality. Successful implementation of the method will help to correctly date 1.5M year old ice being obtained by the Beyond EPICA Oldest Ice project. The DEEPICE Innovative Training Network I am part of is complementary to the drilling project and is funded under the Marie Skłodovksa-Curie Actions by the European Union.