Continuous increase in East Asia HFC-23 emissions inferred from high-frequency atmospheric observations from 2008 to 2019
Abstract. Trifluoromethane (CHF3, HFC-23), one of the most potent greenhouse gases among HFCs, is mainly emitted to the atmosphere as a by-product in the production of the ozone depleting legacy refrigerant and chemical feedstock chlorodifluoromethane (CHClF2, HCFC-22). A recent study on global HFC-23 emissions (Stanley et al., 2020) showed significant discrepancies over 2014–2017 between the increase in the observation-derived (top-down) emissions and the 87 % emission reduction expected from capture and destruction processes of HFC-23 at HCFC-22 production facilities mandated by national phase-out plans (bottom-up). However, the actual sources of the increased emissions were not identified. Here, we estimate the regional top-down emissions of HFC-23 for East Asia based on in situ measurements at Gosan, South Korea, and show that the HFC-23 emissions from eastern China have increased from 5.0 ± 0.4 Gg yr-1 in 2008 to 9.5 ± 1.0 Gg yr-1 in 2019. The continuous rise was contrary to the large emissions reduction reported since 2015 under the Chinese hydrochlorofluorocarbons production phase-out management plan (HPPMP). The magnitude of the mismatch between top-down and bottom-up estimates for 2015–2019 in eastern China was ~23.7 ± 3.6 Gg, which accounts for 47 ± 11 % of the global mismatch.
Given the location of HCFC-22 production plants in eastern China and the fraction of regional to global HCFC-22 production capacities, the HFC-23 emissions rise in eastern China is most likely associated with known HCFC-22 production facilities and thus, observed discrepancies between top-down and bottom-up emissions could be attributed to unsuccessful factory level HFC-23 abatement and inaccurate quantification of emission reductions.
Hyeri Park et al.
Status: final response (author comments only)
RC1: 'Comment on egusphere-2023-6', Anonymous Referee #1, 27 Jan 2023
- AC1: 'Reply on RC1', Hyeri Park, 15 Apr 2023
RC2: 'Comment on egusphere-2023-6', Anonymous Referee #2, 03 Feb 2023
- AC2: 'Reply on RC2', Hyeri Park, 15 Apr 2023
Hyeri Park et al.
Hyeri Park et al.
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This manuscript describes important emission information on key Montreal Protocol controlled and climate related gases. It should be fully published.
The methods used to determine the emissions are widely accepted and appropriate for this study.
My primary concern is one that can be remedied with some careful attention to the discussion to make the reading of the flow a bit better. The discussion is rather disjointed, with a bunch of factual statements of decisions made for the analysis. There is little discussion of why the decisions were made for many of the assumptions. Such discussion would help to make the logic flow a bit better. One such example is at line 220. An assumption is mentioned with no statement of why. The same is true for the discussion of the results. All the discussion related to the figures (which I mostly like) does not naturally flow. For example, a better discussion of the comparison of HFC-23 vs. HCFC-22 emissions and what that REALLY tells us would be helpful. A useful discussion point that this paper COULD address is the distribution of the inferred emissions relative to what is seen for CFC-11.
Other areas that could be described more clearly are how the priors are really constructed relative to the TEAP information regarding the location of the probable production facilities. It was not clear to me how the initial emissions were distributed among the various facilities for the priors, and how they changed.
A few minor points are below…
Abstract: How are the known production locations used in the analysis?
Line 39: the term “basket” is a bit informal. I’d change it to “group”….though did Kyoto really regulate?
The term “top-down” is loosely defined in the abstract, but not in the body of the paper. I suggest doing so, and with a bit more detail than what is done the abstract.
Figure 3…so that these maps can be shown without the caption, I’d put the years of the analysis in the upper left corner of each map.