Previously, NASA GSFC 2D model simulations showed that HFCs modulate the climate of the upper troposphere and stratosphere: HFCs increase atmospheric temperature and enhance the overturning circulation, thus affecting stratospheric ozone concentrations. Under a business-as-usual emissions scenario, HFCs could contribute substantially to anthropogenic middle atmospheric change by the mid-21st century.
Recent estimates suggest that the radiative forcing by HFCs could be as large as 20% that of CO2 by the mid-21st century. A CFC-11-based proxy for the HFCs has been shown to warm surface temperatures, similarly to the effects of increasing CO2. New ocean-atmosphere Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM) simulations with interactive HFCs provide the first quantitative estimates of the contribution of HFCs to future climate change. Specifically, these simulations identify the HFC contributions to future changes in surface temperature, precipitation and interannual variability. GEOSCCM sensitivity simulations contrast the climate impacts of HFCs in a business-as-usual emissions scenario with a scenario depicting the evolution of HFC emissions following the Kigali Amendment to the Montreal Protocol.