IA models have frequently been used to calculate social costs of carbon and a very wide range of estimates for this quantity exists in the literature. Hence this project details the assumptions and data lying behind the assessment of climate change damage in four well known IA models: RICE/DICE, MERGE, PAGE and FUND. Graphics showing how monetized and non-monetized damages vary with temperature in the various models are also provided. The project also assesses how functions vary with socioeconomic scenario and how they handle adaptation. Finally, a comparison is made with the outputs of the parallel report Understanding the Regional Impacts of Climate Change.