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 quantifiable and comparable information regarding the amplitude and speed of natural variations in the ocean, over the continents, and in the cryosphere.
The best way to ascertain the extent of past changes is by analysing historical time series of direct temperature measurements. Information regarding the pre-anthropogenic state of the system can be obtained either by reconstructing the climatic and environmental conditions of the distant past – e.g. using sediment deposits on the seafloor, which contain the remains of past organisms – or by creating temperature curves for the past by simulating the climate using complex models.
One special area of my research is therefore Earth system modelling, which involves e.g. accurately depicting natural climatic variations and revisiting theoretical assumptions used in Earth system analysis. In this regard, we focus on the role of global ocean circulation, and on the interpretation of palaeoclimate data, e.g. from corals, ice cores, and marine sediments. By analysing reconstructed palaeoclimate records and combining them with the findings of our models, we can evaluate climate transitions, as well as their forcing and feedback mechanisms – and for past and future climate changes alike. At the same time, model simulations can help us determine the causes of major and minor variations found in the palaeoclimate data.