Ken Caldeira investigates issues related to climate, carbon and energy systems. His primary tools are climate and the carbon cycle models, although he does field work related to ocean acidification. He studies the global carbon cycle; marine biogeochemistry and chemical oceanography, including ocean acidification and the atmosphere/ocean carbon cycle; land-cover and climate change; the long-term evolution of climate and geochemical cycles; and energy technology. He is a lead author of the “State of the Carbon Cycle Report,” a study requested by the U.S. Congress. His research includes paleoclimate and geochemical cycles and also climate intervention (geoengineering).