Tracking New Halogenated Alkenes in the Atmosphere

Proceedings of the National Academy of Sciences of the United States of America, 2014

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, w...

2010

We report the first measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), a substitute for ozone depleting compounds, in remote regions of the atmosphere and present evidence for its rapid growth. Observed mixing ratios ranged from below 0.01 ppt in deep firn air to 0.59 ppt in the northern mid-latitudinal upper troposphere. 5 Firn air samples collected in Greenland were used to reconstruct a history of atmospheric abundance. Year-on-year increases were deduced, with acceleration in the growth rate from 0.026 ppt per year in 2000 to 0.057 ppt per year in 2007. Upper tropospheric air samples provide evidence for a continuing growth until late 2009. Furthermore we calculated a stratospheric lifetime of 370 years from measurements of 10 air samples collected on board high altitude aircraft and balloons. Emission estimates were determined from the reconstructed atmospheric trend and suggest that current "bottom-up" estimates of global emissions for 2005 are too high by more than a factor of three. 25 2005), as a refrigerant (Emmen et al., 2000; Park et al., 2001), in fire extinguishers 7677 ACPD 10, 7675-7697, 2010 Abstract 25 7678

Environmental Science & Technology, 2009

2020

2016

High frequency, in situ global observations of HCFC-22 (CHClF 2), HCFC-141b (CH 3 CCl 2 F), HCFC-142b (CH 3 CClF 2) and HCFC-124 (CHClFCF 3) and their main HFC replacements HFC-134a (CH 2 FCF 3), HFC-125 (CHF 2 CF 3), HFC-143a (CH 3 CF 3), and HFC-32 (CH 2 F 2) have been used to determine their changing global growth rates and emissions in response to the Montreal Protocol and its recent amendments. The 2007 adjustment to the Montreal Protocol required the accelerated phase-out of HCFCs with global production and consumption capped in 2013, to mitigate their environmental impact as both ozone depleting substances and important greenhouse gases. We find that this change has coincided with a reduction in global emissions of the four HCFCs with aggregated global emissions in 2015 of 444 ± 75 Gg/yr, in CO 2 equivalent units (CO 2 e) 0.75 ± 0.1 Gt/yr, compared with 483 ± 70 Gg/yr (0.82 ± 0.1 Gt/yr CO 2 e) in 2010. (All quoted uncertainties in this paper are 1 sigma). About 80% of the total HCFC atmospheric burden in 2015 is HCFC-22, where global HCFC emissions appear to have been relatively constant in spite of the 2013 cap on global production and consumption. We attribute this to a probable increase in production and consumption of HCFC-22 in Montreal Protocol Article 5 (developing) countries and the continuing release of HCFC-22 from the large banks which dominate HCFC global emissions. Conversely, the four HFCs all show increasing annual growth rates with aggregated global HFCs emissions in 2015 of 329 ± 70 Gg/yr (0.65 ± 0.12 Gt/yr CO 2 e) compared to 2010 with 240 ± 50 Gg/yr (0.47 ± 0.08 Gt/yr CO 2 e). As HCFCs are replaced by HFCs we investigate the impact of the shift to refrigerant blends which have lower global warming potentials (GWPs). We also

The Handbook of Environmental Chemistry

We review the available data concerning the atmospheric chemistry and environmental impact of hydrofluorocarbons (HFCs) and hydrofluoroethers (HFEs). HFCs and HFEs have no impact on stratospheric ozone. The direct global warming potentials of HFCs and HFEs are approximately an order of magnitude less than the CFCs they replace. At the concentrations expected from their atmospheric degradation, none of the oxidation products of HFCs or HFEs, are noxious or toxic.

Atmospheric Environment, 2003

Two of the gases, CFC-12 (dichlorodifluoromethane, CF 2 Cl 2) and HCFC-22 (chlorodifluoromethane, CHClF 2) have long histories of emission from refrigeration and other uses. Production and sales records show the expected fall in the amounts of CFC-12 used in refrigeration after the Montreal Protocol came into effect but this does not seem to have been accompanied by significant substitution by HCFC-22, demand for which appears governed by organic growth. HFC-134a (1,1,1,2-tetrafluoroethane, CH 2 FCF 3) is a relative newcomer that has partially substituted for CFC-12. After developing a single data set for the global use of each substance in refrigeration, foam blowing and aerosol propulsion, and other promptly emissive uses, annual releases of the compounds were estimated by applying emission functions derived from surveying both the producers of the chemicals and the principal industrial users. For CFC-12 and HFC-134a, atmospheric concentrations calculated from the emissions estimated here are in good agreement with observations, verifying that the emission functions adequately describe the relationship between the quantities in use, the atmospheric lifetimes of 100 and 14.6 years, respectively, and the extent of release into the atmosphere. The agreement between observation and calculation is poorer for HCFC-22, if its atmospheric lifetime is 12 years, but becomes much closer with a lifetime of 10 years. An 80% reduction in CFC requirement has been substituted only to the extent of 25% by HFC-134a. This is consistent with improved technology to curtail leakage and so enable lower system charges that, in turn, translate into less demand. For the same reason, the refrigeration emission function for HFC-134a over the period 1990-2000 was not significantly different from that of CFC-12. The lower absolute rate of leakage and lower absolute charge sizes combining to maintain a similar relative rate of loss.

2017

Based on observations of the chlorofluorocarbons CFC-13 (chlorotrifluoromethane), CFC-114 (combined measurement of both isomers of dichlorotetrafluoroethane), and CFC-115 (chloropentafluoroethane) in atmospheric and firn samples, we reconstruct records of their tropospheric histories spanning nearly 8 decades. These compounds were measured in polar firn air samples, in ambient air archived in canisters, and in situ at the AGAGE (Advanced Global Atmospheric Gases Experiment) network and affiliated sites. Global emissions to the atmosphere are derived from these observations using an inversion based on a 12-box atmospheric transport model. For CFC-13, we provide the first comprehensive global analysis. This compound increased monotonically from its first appearance in the atmosphere in the late 1950s to a mean global abundance of 3.18 ppt (dry-air mole fraction in parts per trillion, pmol mol −1) in 2016. Its growth rate has decreased since the mid-1980s but has remained at a surprisingly high mean level of 0.02 ppt yr −1 since 2000, resulting in a continuing growth of CFC-13 in the atmosphere. CFC-114 increased from its appearance in the 1950s to a maximum of 16.6 ppt in the early 2000s and has since slightly declined to 16.3 ppt in 2016. CFC-115 increased monotonically from its first appearance in the 1960s and reached a global mean mole frac-Published by Copernicus Publications on behalf of the European Geosciences Union. 980 M. K. Vollmer et al.: Minor CFCs tion of 8.49 ppt in 2016. Growth rates of all three compounds over the past years are significantly larger than would be expected from zero emissions. Under the assumption of unchanging lifetimes and atmospheric transport patterns, we derive global emissions from our measurements, which have remained unexpectedly high in recent years: mean yearly emissions for the last decade (2007-2016) of CFC-13 are at 0.48 ± 0.15 kt yr −1 (> 15 % of past peak emissions), of CFC-114 at 1.90 ± 0.84 kt yr −1 (∼ 10 % of peak emissions), and of CFC-115 at 0.80 ± 0.50 kt yr −1 (> 5 % of peak emissions). Mean yearly emissions of CFC-115 for 2015-2016 are 1.14 ± 0.50 kt yr −1 and have doubled compared to the 2007-2010 minimum. We find CFC-13 emissions from aluminum smelters but if extrapolated to global emissions, they cannot account for the lingering global emissions determined from the atmospheric observations. We find impurities of CFC-115 in the refrigerant HFC-125 (CHF 2 CF 3) but if extrapolated to global emissions, they can neither account for the lingering global CFC-115 emissions determined from the atmospheric observations nor for their recent increases. We also conduct regional inversions for the years 2012-2016 for the northeastern Asian area using observations from the Korean AGAGE site at Gosan and find significant emissions for CFC-114 and CFC-115, suggesting that a large fraction of their global emissions currently occur in northeastern Asia and more specifically on the Chinese mainland.

Journal of Geophysical Research, 2011

We report on ground-based atmospheric measurements and emission estimates of the four anthropogenic hydrofluorocarbons (HFCs) HFC-365mfc (CH 3 CF 2 CH 2 CF 3 ,

Journal of Geophysical Research: Atmospheres, 2004