Veerabhadran "Ram" Ramanathan discovered the greenhouse effect of CFCs in 1975 and showed that a ton each of CFC-11 and CFC-12 has more global warming effect than 10000 tons of CO2.  This discovery established the now accepted fact that non-CO2 gases are a major contributor to planet warming and also enabled the Montreal protocol to become the first successful climate mitigation policy. For this work, he was awarded the Tyler Prize by Nobel Laureate Sherwood Rowland in 2009. In 1980, Madden and Ramanathan were the first to make a statistical prediction that global warming will be detected above the background noise by 2000, a prediction which was verified by the IPCC-UN experts in 2001. He led a NASA study with its climate satellite to show that clouds had a net cooling effect on the planet and quantified the radiation interactions with water vapor and its amplification of the CO2 warming. He led international field campaigns, developed unmanned aircraft platforms for tracking brown clouds  pollution worldwide.  His work has led to numerous policies including the formation of the Climate and Clean Air Coalition by the United Nations.

He founded, designed, and leads Project Surya along with daughters Nithya Ramanathan and Tara Ramanathan; an extended effort to characterize and mitigate climate and health impacts of cooking with solid biomass as a way to protect the bottom three billion from climate change. He is now leading a University of California  climate solutions effort which has launched a course on climate solutions that is expected to reach a million students or more.

Ramanathan was honored as the science advisor to Pope Francis’ holy see delegation to the historic 2015 Paris climate summit and advised California Gov. Jerry Brown. He was named the U.N. Climate Champion in 2013; has been elected to the U.S. National Academy and the Royal Swedish Academy which awards the Nobel prizes. Foreign Policy named him a thought leader in 2014; In 2018, he (with James Hansen) was named Tang Laureate for sustainability science.