Quantifying California HFC Emissions with the AGAGE Network

Abstract: Introduced as benign replacements for ozone-depleting CFCs and HCFCs, HFCs are potent greenhouse gases that are released into the atmosphere from a variety of human activities, including refrigeration, air conditioning, and foam blowing. Although occurring in trace abundances, global CO2-equivalent emissions are equivalent to around two-thirds of current global methane emissions from the oil and gas sector.

Top-down HFC emissions estimates inferred from observations of atmospheric abundances often fundamentally disagree with bottom-up HFC emissions inventories inferred from industrial activity data. Some bottom-up estimates report static or decreasing emissions while top-down emission estimates are increasing. In either case, atmospheric abundances of major most HFCs are still increasing, which is a concern given the strong global warming potential of many HFCs.

Due to data sparsity, there are limited regional top-down emissions estimates of HFC emissions. Leveraging long-term monitoring stations of the AGAGE network in California at Trinidad Head and the Scripps Institution of Oceanography, we present a regional-scale top-down estimate of HFC emissions in California and comparison with bottom-up inventories. This quantification serves to evaluate regional bottom-up HFC emissions inventories for California and the Western United States and to demonstrate the utility and importance of long-term, high-resolution monitoring of halogenated GHGs.