Environmental policy of the United States from the sun. Chlorofluorocarbons (CFCs), which were used beginning in the 1930s in a number of important areas, were determined in 1974 to be responsible for much of the depletion of the ozone layer. Four years later, the EPA and FDA banned CFCs in aerosol cans. As research in the 1980s indicated that the problem was worse than before, and revealed a controversial massive hole in the ozone layer over Antarctica, three international agreements were made to reduce the ozone-damaging substances- the Vienna Convention, the 1987 Montreal Protocol, and a third agreement in 1990 in London. In the United States,
Montreal Protocol and HCFCs. Thus, in 2009, a study calculated that a fast phasedown of high-GWP HFCs could potentially prevent the equivalent of up to 8.8 Gt CO2-eq "per year" in emissions by 2050. A proposed phasedown of HFCs was hence projected to avoid up to 0.5C of warming by 2100 under the high-HFC growth scenario, and up to 0.35C under the low-HFC growth scenario. Recognizing the opportunity presented for fast and effective phasing down of HFCs through the Montreal Protocol, starting in 2009 the Federated States of Micronesia proposed an amendment to phase down high-GWP HFCs, with the U.S., Canada, and