Increase in HFC‐134a emissions in response to the success of the Montreal Protocol

Abstract

The 1,1,1,2-tetrafluoroethane (HFC-134a), an important alternative to CFC-12 in accordance with the Montreal Protocol on Substances that Deplete the Ozone Layer, is a high global warming potential greenhouse gas. Here we evaluate variations in global and regional HFC-134a emissions and emission trends, from 1995 to 2010, at a relatively high spatial and temporal (3.75°in longitude × 2.5°in latitude and 8 day) resolution, using surface HFC-134a measurements. Our results show a progressive increase of global HFC-134a emissions from 19 ± 2 Gg/yr in 1995 to 167 ± 5 Gg/yr in 2010, with both a slowdown in developed countries and a 20%/yr increase in China since 2005. A seasonal cycle is also seen since 2002, which becomes enhanced over time, with larger values during the boreal summer.

History of chemically and radiatively important atmospheric gases from the Advanced Global Atmospheric Gases Experiment (AGAGE)

“…Using HCFC-22 measurements for estimating the average OH yields similar results to those derived from CH 3 CCl 3 but with less accuracy (Miller et al, 1998;Fortems-Cheiney et al, 2013). The industrial gases HFC-134a, HCFC-141b, and HCFC-142b are potentially useful OH estimators but the accuracy of their emission estimates needs improvement (Huang and Prinn, 2002;Fortems-Cheiney et al, 2015). At the present time, to augment CH 3 CCl 3 , the potential OH estimation species (the major tropospheric sink is reaction with OH, and industrial emissions estimations are relatively good) are HFC-134a, HCFC-141b, HCFC-142b, and possibly some of the newly introduced HFCs .…”

“…Note also the evolution of the sizes of these pollution events between 2004 and 2016 associated with the decreases in the emissions of regulated gases and the growth of emissions of unregulated ones. This high-frequency sampling enables the pollution events in particular to be used to estimate emissions from nearby source regions (e.g., Cape Grim station for SE Australian emissions; e.g., Dunse et al, 2005;Stohl et al, 2009;O'Doherty et al, 2009;Fraser et al, 2014;Lunt et al, 2015), Trinidad Head for the west coast US emissions (e.g., Li et al, 2005;O'Doherty et al, 2009;Lunt et al, 2015;Fortems-Cheiney et al, 2015), Mace Head and the other European stations for European and in some cases eastern USA emissions (e.g., O'Doherty et al, 2009;Stohl et al, 2009;Keller et al, 2012;Simmonds et al, 2015;Lunt et al, 2015;Fortems-Cheiney et al, 2015;Graziosi et al, 2017), and Hateruma, Shangdianzi, and Gosan for East Asian emissions (e.g., Stohl et al, 2009Stohl et al, , 2010Kim et al, 2010;Li et al, 2011;Yao et al, 2012a, b;Fang et al, 2015;Lunt et al, 2015;Fortems-Cheiney et al, 2015). The sources of many anthropogenic and natural trace gases measured in AGAGE are often colocated so that measurement of a wide range of gases enhances the ability to accurately estimate their sources and sinks.…”

Author Replies to Referees #1 and #2: Prinn et al, MS# essd-2017-134, History of Chemically and Radiatively Important Atmospheric Gases from the Advanced 2 Global Atmospheric Gases Experiment (AGAGE)

“…Using HCFC-22 measurements for estimating the average OH yields similar results to those derived from CH 3 CCl 3 but with less accuracy (Miller et al, 1998;Fortems-Cheiney et al, 2013). The industrial gases HFC-134a, HCFC-141b, and HCFC-142b are potentially useful OH estimators but the accuracy of their emission estimates needs improvement (Huang and Prinn, 2002;Fortems-Cheiney et al, 2015). At the present time, to augment CH 3 CCl 3 , the potential OH estimation species (the major tropospheric sink is reaction with OH, and industrial emissions estimations are relatively good) are HFC-134a, HCFC-141b, HCFC-142b, and possibly some of the newly introduced HFCs (Liang et al, 2017).…”

“…Note also the evolution of the sizes of these pollution events between 2004 and 2016 associated with the decreases in the emissions of regulated gases and the growth of emissions of unregulated ones. This high-frequency sampling enables the pollution events in particular to be used to estimate emissions from nearby source regions (e.g., Cape Grim station for SE Australian emissions; e.g., Dunse et al, 2005;Stohl et al, 2009;O'Doherty et al, 2009;Fraser et al, 2014;Lunt et al, 2015), Trinidad Head for the west coast US emissions (e.g., Li et al, 2005;O'Doherty et al, 2009;Lunt et al, 2015;Fortems-Cheiney et al, 2015), Mace Head and the other European stations for European and in some cases eastern USA emissions (e.g., O'Doherty et al, 2009;Stohl et al, 2009;Keller et al, 2012;Simmonds et al, 2015;Lunt et al, 2015;Fortems-Cheiney et al, 2015;Graziosi et al, 2017), and Hateruma, Shangdianzi, and Gosan for East Asian emissions (e.g., Stohl et al, 2009Stohl et al, , 2010Kim et al, 2010;Li et al, 2011;Yao et al, 2012a, b;Fang et al, 2015;Lunt et al, 2015;Fortems-Cheiney et al, 2015). The sources of many anthropogenic and natural trace gases measured in AGAGE are often colocated so that measurement of a wide range of gases enhances the ability to accurately estimate their sources and sinks.…”

“…Kirschke et al (2013) used AGAGE, GMD flask, CSIRO flask, and UCI aircraft data for estimating methane emissions. MIPAS, AGAGE, and GMD data were used by Chirkov et al (2016) for estimating HCFC-22 emissions, and AGAGE and GMD data were used for estimating CCl 4 emissions (Chipperfield et al, 2016); GOSAT, AGAGE, and GMD data were used for estimating regional methane emissions (Fraser et al, 2013). Saunoir et al (2016Saunoir et al ( , 2017 used multi-network data and alternative models to elucidate the 2000-2012 methane budget and its multiyear variability.…”