Royal Society Discussion Meeting: IPCC Thursday 1 to Friday 2 March 2007 Discussion meeting held at the Royal Society By Professor Peter Cox, Professor Brian Hoskins CBE FRS, Professor John Mitchell OBE FRS, Dr Tim Palmer FRS and Professor John Pyle FRS. Climate change is one of the most important challenges of our time. In 2001 the Intergovernmental Panel on Climate Change (IPCC) highlighted that human activities are causing concentrations of greenhouse gases to rise at a rate that is unprecedented in the last 20,000 years and carbon dioxide levels are now higher than they have been for 650,000 years. Since 2001 our understanding of the world's climate system and the role of human activity has increased. This meeting showcases "The science of climate change" working group 1 report. The event will highlight the main findings of the report, particularly those areas likely to be of specific interest to the scientific and policy community. The emphasis will be on the advances in our understanding of the science and causes of climate change, since the Third Assessment Report in 2001, and identifying new research priorities and knowledge gaps 1 March 2007 - 2 March 2007