My research centres on past climate change, with a focus on (i) understanding how and why climate has changed in the past and (ii) what we can learn about the future from the past.  My main tools are climate models, and much of my work is underpinned by model-data comparisons.

(i) The analysis and interpretation of past climate data has led to the formation of many hypotheses regarding the mechanisms affecting past climate change. Models are ideal tools to test these hypotheses. In addition, modelling can itself lead to hypotheses which are testable by the collection and interpretation of new data, and can indicate regions in which new data could usefully be collected.

(ii) Past climate data can also inform our predictions of the future, through providing analogues of future climate change under high carbon dioxide concentrations, and through the evaluation of models used to predict the future.

Both of these aspects are central to the Deep-Time Model Intercomparison Project (DeepMIP), which I lead. 

Much of my work focuses on characterising Climate Sensitivity, the globally averaged increase in temperature due to a doubling of carbon dioxide.  Associated with this I am a Lead Author on the forthcoming Intergovernmental Panel on Climate Change sixth assessment report (IPCC AR6).