On September 27, U.S. President Barack Obama met with Indian Prime Minister Manmohan Singh to discuss how to improve ties on a number of issues between the countries, including how to support efforts to phase-down the super greenhouse gases HFCs (hydrofluorocarbons). HFCs, primarily used in refrigeration, air conditioning, and foam blowing, are extremely harmful to the climate as they are hundreds and thousands of times more potent than carbon dioxide (CO2).