The evidence for increasing emissions of CFC-11

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Nicholas Nelson
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The evidence for increasing emissions of CFC-11 Based on the paper published 17 May 2018: An unexpected and persistent increase in global emissions of ozone-depleting CFC-11 S.A. Montzka 1, G.

W. Elkins 1. 1 Global Monitoring Division, NOAA/ESRL, Boulder, USA, 2 CIRES, Univ.

1 The evidence for increasing emissions of CFC-11 Based on the paper published 17 May 2018: An unexpected and persistent increase in global emissions of ozone-depleting CFC-11 S.A. Montzka 1, G. Dutton 1,2, P. Yu 2,3, E. Ray 2,3, R. Portmann 3, J. Daniel 3, L. Kuijpers 4, B.D. Hall 1, D Mondeel 1,2, C. Siso 1,2, J. D. Nance 1,2, M Rigby 5, A.J. Manning 6, L. Hu 1,2, F. Moore 1,2, B.R. Miller 1,2, and J.W. Elkins 1. 1 Global Monitoring Division, NOAA/ESRL, Boulder, USA, 2 CIRES, Univ. of Colorado, Boulder, USA, 3 Chemical Sciences, Division, NOAA/ESRL, Boulder, USA 4 A/Gent Consultancy, BV, Venlo, The Netherlands 5 School of Chemistry, Univ. of Bristol, Bristol, UK 6 UK Met office, Exeter, UK Nature, 557, , EARTH SYSTEM RESEARCH LABORATORY 1

2 Outline: 1) Atmospheric concentrations 2) Derived emissions 3) Location of increasing emissions 4) New, unreported production 2

NOAA s network for measuring ozone-depleting gas concentrations BRW THD NWR MLO KUM ALT SUM MHD Sampling in cooperation with international and national partners: Measurements by three methods: Hourly

3 NOAA s network for measuring ozone-depleting gas concentrations BRW THD NWR MLO KUM ALT SUM MHD Sampling in cooperation with international and national partners: Measurements by three methods: Hourly on site, 5 to 6 sites Weekly flasks, 12 sites, and two methods: GCMS & GC-ECD SMO Canada (AES) UK (Univ Bristol, UK Met office) Australia (CSIRO) Israel (Weizman Inst.) Ireland Harvard Univ. Scripps Univ of Colorado AGAGE Univ. Wisconsin CGO PSA SPO 3

4 CFC-11 (ppt) Atmospheric CFC-11 what we have observed South North Monthly means by site From one method (flasks & GC-MS) Year spo psa psa cgo cgo smo smo mlo mlo kum kum nwr nwr brw brw alt sum alt thd sum mhd thd NH fit mhd SH fit Dashed lines are from fits to data from 2002 to

5 Difference (N S; ppt) North - South (ppt) Global rate (per yr) Rate of change (%/yr) Concentration Mole fraction (ppt) (hemispheric Hemispheric mean means (ppt) ppt) Atmospheric CFC-11 what we have observed a In situ & flasks b % % -0.4% -0.6% -0.8% -1.0% -1.2% c -1.4% SH NH Hemispheric mean concentration Reported production phase-out Multiple blue (or red) lines represent results from different methods Montzka et al.,

6 Difference (N S; ppt) North - South (ppt) Global rate (per yr) Rate of change (%/yr) Concentration Mole fraction (ppt) (hemispheric Hemispheric mean means (ppt) ppt) Atmospheric CFC-11 what we have observed a SH NH Hemispheric mean concentration 230 b % -0.2% In situ & flasks Global rate of change -0.4% -0.6% -0.8% -1.0% -1.2% In situ & flasks c -1.4% Slower decline Faster decline Different colors = different methods In absence of emissions CFC-11 decline would be 2%/yr Reported production phase-out Montzka et al.,

7 Difference (N S; ppt) North - South (ppt) Global rate (per yr) Rate of change (%/yr) Concentration Mole fraction (ppt) (hemispheric Hemispheric mean means (ppt) ppt) Atmospheric CFC-11 what we have observed a SH NH Hemispheric mean concentration 230 b % -0.2% -0.4% -0.6% -0.8% -1.0% -1.2% c -1.4% In situ & flasks In situ & flasks Global rate of change Hemispheric concentration difference Different colors = different methods 2.0 flasks only Montzka et al.,

8 Difference (N S; ppt) North - South (ppt) Global rate (per yr) Rate of change (%/yr) Concentration Mole fraction (ppt) (hemispheric Hemispheric mean means (ppt) ppt) Atmospheric CFC-11 what we have observed a b % -0.2% -0.4% -0.6% -0.8% -1.0% -1.2% c -1.4% SH NH In situ & flasks In situ & flasks Hemispheric mean concentration Global rate of change Hemispheric concentration difference The results reflect real atmospheric changes, given that: The slowdown is observed by multiple instruments using different techniques with independently maintained standardization At all sites A concurrent change is observed in both rate and distribution (hemispheric difference) 2.0 flasks only Montzka et al.,

9 Take-home message #1: Since 2013, the annual decline in CFC-11 concentration has been only half as fast as it was over the previous decade ( ) the slowdown started in the northern hemisphere and has led to a larger hemispheric concentration difference in contrast, the expectation was that the decline would accelerate after 2010, when global production was to have been eliminated 6

10 Difference (N S; ppt) North - South (ppt) Global rate (per yr) Rate of change (%/yr) Concentration Mole fraction (ppt) (hemispheric Hemispheric mean means (ppt) ppt) Atmospheric CFC-11 what we have observed a SH NH Hemispheric mean concentration 230 b % -0.2% -0.4% -0.6% -0.8% -1.0% -1.2% c -1.4% In situ & flasks In situ & flasks Global rate of change Hemispheric concentration difference Taken together imply an increase in CFC-11 emissions to the northern hemisphere 2.0 flasks only Montzka et al.,

11 Emission or Production (Gg/yr) Derived CFC-11 emission Global CFC-11 concentration changes reflect the balance of a) EMISSION b) REMOVAL (lifetime & transport) d[cfc-11]/dt = Emission Removal Constant over time?? Derived Emission Reported Global Production Montzka et al., ± 5 Gg/yr (25%) increase (assuming constant lifetime) A 3-D modeling of transport and loss processes indicates: * An emission increase is required to fit to the data * But the increase may be smaller than indicated (6 to 13 Gg/yr) 8

12 Emission or Production (Gg/yr) Derived CFC-11 emission Global CFC-11 concentration changes reflect the balance of a) EMISSION b) REMOVAL (lifetime & transport) d[cfc-11]/dt = Emission Removal Constant over time?? Derived Emission Reported Global Production Gg/yr above expectations Montzka et al.,

13 Emission or Production (Gg/yr) Derived CFC-11 emission Global CFC-11 concentration changes reflect the balance of a) EMISSION b) REMOVAL (lifetime & transport) d[cfc-11]/dt = Emission Removal Derived Emission Reported Global Production Updated result for 2017 (not in paper): Preliminary emission estimate for 2017 as large as average minimally Influenced by dynamics ~ 40 Gg higher than expected 8

14 Take-home message #2: Emissions of CFC-11 increased after 2012 and have remained elevated in all years since. a) the increase is about 13 ± 5 Gg/yr (25%), but may be an overestimate for b) 2017 emissions are equally high c) such changes are not observed for other chemicals in contrast, decreasing emissions were expected once production was eliminated although some small CFC emission increases are expected in the future from developed countries during building demolition (SROC, 2005) 9

15 Where have CFC-11 emissions increased? * Measurements downwind of emissive regions can be used to derive regional CFC-11 emission magnitudes * No significant emission increases from the U.S. or Europe are implied from observations in these regions recently: CFC-11 emissions from western Europe (unpublished) CFC-11 emissions from the continental U.S. Hu et al., GRL, 2017 Derived from measurements (20 sites) over the U.S. (NOAA) A. Manning (UK Met Office): Derived from measurements (sites MHD and TAC) with procedures to estimate UK emissions of all non-co 2 Kyoto Protocol gases. These are reported annually in the UK National Inventory Report to the UNFCCC. 10

16 Where have CFC-11 emissions increased? Measurements in background air throughout the globe show: a) an increase in the Northern hemisphere relative to the Southern b) increased variability in concentrations measured at sites in the Pacific Ocean 11

8 1 Fraction of year 225 220 215 210 205 200 255 250 245 240 235 230 HCFC-22 (ppt) HCFC-22 (ppt) HCFC-22 (ppt) HCFC-22 (ppt) * air reaching Hawaii in

17 CFC-11 (ppt) CFC-11 (ppt) CFC-11 (ppt) CFC-11 (ppt) Where have CFC-11 emissions increased? Measurements at Hawaii H1 L1 HCFC Fraction of year HCFC-22 (ppt) HCFC-22 (ppt) HCFC-22 (ppt) HCFC-22 (ppt) * air reaching Hawaii in autumn can be influenced by Eurasian emissions,** which bring higher concentrations of chemicals known to be emitted from Eurasia: e.g., HCFC-22, CH 2 Cl 2, & CO. H1 L1 g-s/m 3 : 1e-9 1e-12 g-s/m 3 : 1e-9 1e-12 Montzka et al., 2018 ** Lin et al., Nature Geosci.,

18 CFC-11 (ppt) CFC-11 (ppt) Regresssion coeff. (r 2 ) regression coef. (r 2 ) CFC-11 (ppt) CFC-11 (ppt) Where have CFC-11 emissions increased? Measurements at Hawaii Fraction of year Montzka et al., 2018 HCFC-22 CFC HCFC-22 (ppt) HCFC-22 (ppt) HCFC-22 (ppt) HCFC-22 (ppt) * air reaching Hawaii in autumn can be influenced by Eurasian emissions,** which bring higher concentrations of chemicals known to be emitted from Eurasia: e.g., HCFC-22, CH 2 Cl 2, & CO CFC-11 vs. HCFC Year Only after 2012 does air from eastern Asia contain elevated CFC-11 concentrations Correlations among HCFC-22, CH 2 Cl 2, & CO are strong in all years 12

19 Where have CFC-11 emissions increased? Measurements at Hawaii Summed footprints of those samples in each year having the lowest and highest [HCFC-22] during autumn: Lower [HCFC-22] & [CFC-11] Higher [HCFC-22] & [CFC-11] 13

20 Take-home message #3: 3) Emissions of CFC-11 from eastern Asia have increased since the emission increase from this region is not well quantified at the present time a more accurate regional estimate of emissions over time from this region will come from an analysis of measurements obtained at eastern Asian sites in China, S. Korea (Gosan station on Jeju Island), and Japan (Hateruma and Cape Ochiishi) emission increases are NOT inferred for North America or Western Europe emission region is not the same as production region 14

21 Implied annual release from bank (%/yr) Is the emission increase likely associated with post-2010 production of CFC-11? Emission or Production (Gg/yr) Implied annual release fraction from bank (%/yr) Emission or Production (Gg/yr) % 6% 5% 4% 3% Emission Reported Production 2% Year OR: Could a change in the escape rate of CFC- 11 from the bank account for the increased emission? With no new production, the escape rate from the bank would have had to nearly double since the early 2000s this seems highly unlikely Montzka et al.,

22 Implied annual release from bank (%/yr) Is the emission increase likely associated with post-2010 production of CFC-11? Emission or Production (Gg/yr) Implied annual release fraction from bank (%/yr) Emission or Production (Gg/yr) % 6% 5% 4% 3% Emission Reported Production 2% Year Dashed-gray lines: emissions expected if the escape rate from the bank had remained constant over time 15

23 Implied annual release from bank (%/yr) Is the emission increase likely associated with post-2010 production of CFC-11? Emission or Production (Gg/yr) Implied annual release fraction from bank (%/yr) Emission or Production (Gg/yr) % 6% 5% 4% 3% Emission Reported Production 2% Year Dashed-gray lines: emissions expected if the escape rate from the bank had remained constant over time The cumulative excess emission of CFC-11 through 2016 is about Gg Or ~200 Gg if 2017 included 15

24 Other potential reasons for increased emissions of CFC-11: Increased releases from banked CFC-11 could be from: CFC-11 emission from building-related demolition: expected in the future, and to be fairly small (~75 Gg total, SROC(2005)), and to occur first in the U.S. and Europe, not eastern Asia. CFC-11 emission from refrigerant waste streams: A recent estimate from China (Duan et al., 2018) suggests only very small emissions (<0.2 Gg CFC-11/yr from ) Could inadvertent production explain the observations? CFC-11 emission from inadvertent by-production: From over-fluorination of CHCl 3 in HCFC-22 production? From contaminant CCl 4 in HCFC-22 production? Magnitudes seem too high and timing difficult to understand. Would still represent unreported CFC-11 production. 16

25 Summary of take-home points: 1) Since 2013, the annual decline in CFC-11 concentration has been only half as fast as it was over the previous decade ( ). a very robust result 2) Emissions of CFC-11 increased after 2012 and have remained elevated in all years since emission is also high 3) Emissions of CFC-11 from eastern Asia have increased since exact country not identified by these data 4) The observations suggest unreported production of CFC- 11 after the 2010 global phase-out. but we don t have proof 5) Detecting and diagnosing atmospheric composition change requires an extensive network of high quality measurements, and accurate and sophisticated modeling tools. 17

6. HALOCARBONS :IN SITU STATION :FLASK STATION 90N 60N 30N 30S 60S 90S

6. HALOCARBONS :IN SITU STATION :FLASK STATION 90N 60N 30N EQ 30S 60S 90S 120W 60W 0 60E 120E 180 (a) CFC-11 Monthly Data 120 140 160 180 200 220 240 260 280 300 AMY236N00 LMP635N00 KSN233N00 (b) CFC-12