He has worked in climate modelling since 1992, with a particular interest in the impacts of climate change on ecosystems and the interactions with other impacts of climate change such as on water resources. He is also interested in the wide-ranging effects of land use and land cover change on climate. He has pioneered a number of key developments in the extension of climate models to include biological processes.

Richard is project director for the writing of the technical chapters of the Evidence Report for the UK's 3rd national Climate Change Risk Assessment (CCRA3). He led the EU Framework 7 Project HELIX (High-End cLimate Impacts and eXtremes), which assessed the impacts of climate change at 1.5, 2, 4°C global warming above pre-industrial state.

Richard was a lead author on the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) in Working Group 1 (The Physical Science Basis), leading the assessment of the influences of land cover change on climate and contributing to the assessment of climate change impacts on fresh water. He played a similar role in the Millennium Ecosystem Assessment. He was a lead author on the IPCC 5th Assessment Report in Working Group 2 (Impacts, Adaptation and Vulnerability), responsible for assessing the impacts of climate change on terrestrial ecosystems, and in the IPCC 6th Assessment he is a lead author on the Working Group 2 chapter on Water.