title: Global emissions of refrigerants HCFC-22 and HFC-134a: unforeseen seasonal contributions.
abstract: HCFC-22 (CHClF2) and HFC-134a (CH2FCF3) are two major gases currently used worldwide in domestic and commercial refrigeration and air conditioning. HCFC-22 contributes to stratospheric ozone depletion, and both species are potent greenhouse gases. In this work, we study in situ observations of HCFC-22 and HFC-134a taken from research aircraft over the Pacific Ocean in a 3-y span [HIaper-Pole-to-Pole Observations (HIPPO) 2009-2011] and combine these data with long-term ground observations from global surface sites [National Oceanic and Atmospheric Administration (NOAA) and Advanced Global Atmospheric Gases Experiment (AGAGE) networks]. We find the global annual emissions of HCFC-22 and HFC-134a have increased substantially over the past two decades. Emissions of HFC-134a are consistently higher compared with the United Nations Framework Convention on Climate Change (UNFCCC) inventory since 2000, by 60% more in recent years (2009-2012). Apart from these decadal emission constraints, we also quantify recent seasonal emission patterns showing that summertime emissions of HCFC-22 and HFC-134a are two to three times higher than wintertime emissions. This unforeseen large seasonal variation indicates that unaccounted mechanisms controlling refrigerant gas emissions are missing in the existing inventory estimates. Possible mechanisms enhancing refrigerant losses in summer are (i) higher vapor pressure in the sealed compartment of the system at summer high temperatures and (ii) more frequent use and service of refrigerators and air conditioners in summer months. Our results suggest that engineering (e.g., better temperature/vibration-resistant system sealing and new system design of more compact/efficient components) and regulatory (e.g., reinforcing system service regulations) steps to improve containment of these gases from working devices could effectively reduce their release to the atmosphere.
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138; bxiang@seas.harvard.edu.
authors.forename: Bin
authors.initials: B
authors.lastname: Xiang
authors.affiliation: Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology, Yokohama 236 0001, Japan;
authors.forename: Prabir K
authors.identifier: http://orcid.org/0000-0001-5700-9389
authors.initials: PK
authors.lastname: Patra
authors.affiliation: National Oceanic and Atmospheric Administration Earth System Research Laboratory, Global Monitoring Division Halocarbon and other Trace Gases Group, Boulder, CO 80305;
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Montzka
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138;
authors.forename: Scot M
authors.initials: SM
authors.lastname: Miller
authors.affiliation: National Oceanic and Atmospheric Administration Earth System Research Laboratory, Global Monitoring Division Halocarbon and other Trace Gases Group, Boulder, CO 80305;
authors.forename: James W
authors.initials: JW
authors.lastname: Elkins
authors.affiliation: National Oceanic and Atmospheric Administration Earth System Research Laboratory, Global Monitoring Division Halocarbon and other Trace Gases Group, Boulder, CO 80305; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309;
authors.forename: Fred L
authors.initials: FL
authors.lastname: Moore
authors.affiliation: Department of Atmospheric Sciences, Rosenstiel School of Marine & Atmospheric Science, University of Miami, Miami, FL 33149;
authors.forename: Elliot L
authors.initials: EL
authors.lastname: Atlas
authors.affiliation: National Oceanic and Atmospheric Administration Earth System Research Laboratory, Global Monitoring Division Halocarbon and other Trace Gases Group, Boulder, CO 80305; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309;
authors.forename: Ben R
authors.initials: BR
authors.lastname: Miller
authors.affiliation: Geosciences Research Division, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093; and.
authors.forename: Ray F
authors.initials: RF
authors.lastname: Weiss
authors.affiliation: Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Prinn
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138;
authors.forename: Steven C
authors.initials: SC
authors.lastname: Wofsy
keywords: HCFC-22; HFC-134a; emission seasonality; global emissions; refrigerants