His most recent work values the impacts of greenhouse gases, including the effects of climate change on agriculture, forests, water resources, energy, and coasts.

Together with William Nordhaus and Daigee Shaw, they have invented the Ricardian technique, a cross-sectional analysis that reveals the climate sensitivity of agriculture.

With Wendy Morrison and Erin Mansur, cross-sectional information from households and firms was used to measure the impacts of climate change on energy.

With James Neumann, Mendelsohn led a consortium of leading impact researchers on a complete study of the effect of climate change on the United States economy.

With Ariel Dinar, Niggol Seo, Pradeep Kurukulasuriya, and a host of country collaborators in Africa and Latin America, they have completed a series of studies of the impact of climate change on agriculture in those two continents.

With Gardner Brown, they invented the hedonic travel cost method that measures the values of site characteristics such as old growth and fish populations.

Working with Nicholas Muller, this model has been recently been extended to cover all air pollution sources in the United States.

New regulations can be designed to be far more efficient at reducing damages compared to current approaches including cap and trade.