"There is a pressing need to improve our understanding of climate processes and their impacts in order to develop appropriate adaptation and mitigation measures. Increasing concentrations of anthropogenic greenhouse gases (GHGs) are known to be causing changes in global climate patterns, and will continue to do so for the foreseeable future. However, our ability to predict future climatic states is still limited for a variety of reasons. Key among these is our understanding of the coupled behaviour of the components of the Earth system that contribute to the evolution of GHG concentrations, climate responses, and the impacts of environmental change. Earth System Models (ESMs) have emerged as our most important tool with which to test our understanding and predict the coupled behaviour of the many interacting components. However, a variety of recent observations indicate that changes are occurring at faster rates than predicted, suggesting that we are underestimating the strength of feedbacks in the Earth system. We propose a research training programme that will have as its scientific focus the evaluation, improvement, and application of a range of different ESMs. We will consider all the important anthropogenic greenhouse gases and will undertake a range of projects, broadly classed into data and model benchmarking, marine processes, terrestrial processes, high latitude feedbacks, and coupled modelling. Science projects by individual fellows will enhance links between network partners as well as considerably improve our understanding of Earth system feedbacks. A comprehensive, coordinated range of training events will be provided. We will foster the next generation of Earth system scientists and reduce uncertainties in future Earth system behaviour, thereby greatly improving the quality of knowledge available to policy makers and significantly strengthening European science."