It is of vital importance to understand how increasing human population and industrialization have already caused significant changes in earth's climate. In order to properly address this question, one needs quantitative information regarding the amplitude and rapidity of natural variations in the ocean, over the continents, and in the cryosphere. The best way to ascertain the extent of past changes is through the inspection of historical time series of direct temperature measurements. Information regarding the pre-anthropogenic state of the system can be obtained either from proxies that record past climate and environmental conditions, or by simulating climate using comprehensive models under external forcing.

One special area of my research is therefore focused on Earth system modeling, paleoclimate variability, and theoretical aspects in Earth system analysis. Particular aspects are the role of the global ocean circulation, and the dynamical interpretation of paleoclimate data, e.g. corals, ice cores, and marine sediments. Analyzing reconstructed paleoclimate records and models allows for the evaluation of forcing and feedback mechanisms in past and future climate changes. In return, model simulations can aid in the interpretation of the causes of observed variations in paleoclimate data.

Paleoclimate dynamics contextualises current and future changes, quantifies natural variability, and informs us about mechanisms under various forcings. One key method is through model - data comparisons (out-of-sample evaluation, emergent constraints).