The Experts below are selected from a list of 5703 Experts worldwide ranked by ideXlab platform
M P Chipperfield - One of the best experts on this subject based on the ideXlab platform.
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arctic ozone depletion in 2019 20 roles of chemistry dynamics and the Montreal Protocol
Geophysical Research Letters, 2021Co-Authors: Wuhu Feng, Sandip Dhomse, M Weber, Carlo Arosio, J P Burrows, M L Santee, M P ChipperfieldAbstract:We use a 3‐D chemical transport model and satellite observations to investigate Arctic ozone depletion in winter/spring 2019/20 and compare with earlier years. Persistently low temperatures caused extensive chlorine activation through to March. March‐mean polar‐cap‐mean modelled chemical column ozone loss reached 78 DU (local maximum loss of ∼108 DU in the vortex), similar to that in 2011. However, weak dynamical replenishment of only 59 DU from December to March was key to producing very low (<220 DU) column ozone values. The only other winter to exhibit such weak transport in the past 20 years was 2010/11, so this process is fundamental to causing such low ozone values. A model simulation with peak observed stratospheric total chlorine and bromine loading (from the mid‐1990s) shows that gradual recovery of the ozone layer over the past two decades ameliorated the polar cap ozone depletion in March 2020 by ∼20 DU.
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Fifteen Years of HFC-134a Satellite Observations: Comparisons With SLIMCAT Calculations
2021Co-Authors: Jeremy J Harrison, M P Chipperfield, Sandip Dhomse, Christopher D Boone, Peter F BernathAbstract:The phase out of anthropogenic ozone-depleting substances such as chlorofluorocarbons under the terms of the Montreal Protocol led to the development and worldwide use of hydrofluorocarbons (HFCs) in refrigeration, air conditioning, and as blowing agents and propellants. Consequently, over recent years, the atmospheric abundances of HFCs have dramatically increased. HFCs are powerful greenhouse gases and are now controlled under the terms of the 2016 Kigali Amendment to the Montreal Protocol. HFC-134a is currently the most abundant HFC in the atmosphere, breaking the 100 ppt barrier in 2018, and can be measured in the Earth's atmosphere by the satellite remote-sensing instrument ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer), which has been measuring since 2004. This work uses the ACE-FTS v4.0 data product to investigate global distributions and trends of HFC-134a. These measurements are compared with a simulation of SLIMCAT, a state-of-the-art three-dimensional chemical transport model, which is constrained by global surface HFC-134a measurements. The agreement between observation and model is good, although in the tropical troposphere ACE-FTS measurements are biased low by up to 10–15 ppt. The overall ACE-FTS global trend of HFC-134a for the altitude range 5.5–24.5 km and 2004–2018 time period is approximately linear with a value of 4.49 ± 0.02 ppt/year, slightly lower than the corresponding SLIMCAT trend of 4.66 ppt/year. Using a simple box model, we also estimate the annual global emissions and burdens of HFC-134a from the model data, indicating that emissions of HFC-134a have increased almost linearly, reaching 236 Gg by 2018
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Renewed and emerging concerns over the production and emission of ozone-depleting substances
'Springer Science and Business Media LLC', 2020Co-Authors: M P Chipperfield, Hossaini R, Sa Montzka, Reimann S, Sherry D, Tegtmeier SAbstract:Stratospheric ozone depletion, first observed in the 1980s, has been caused by the increased production and use of substances such as chlorofluorocarbons (CFCs), halons and other chlorine-containing and bromine-containing compounds, collectively termed ozone-depleting substances (ODSs). Following controls on the production of major, long-lived ODSs by the Montreal Protocol, the ozone layer is now showing initial signs of recovery and is anticipated to return to pre-depletion levels in the mid-to-late twenty-first century, likely 2050–2060. These return dates assume widespread compliance with the Montreal Protocol and, thereby, continued reductions in ODS emissions. However, recent observations reveal increasing emissions of some controlled (for example, CFC-11, as in eastern China) and uncontrolled substances (for example, very short-lived substances (VSLSs)). Indeed, the emissions of a number of uncontrolled VSLSs are adding significant amounts of ozone-depleting chlorine to the atmosphere. In this Review, we discuss recent emissions of both long-lived ODSs and halogenated VSLSs, and how these might lead to a delay in ozone recovery. Continued improvements in observational tools and modelling approaches are needed to assess these emerging challenges to a timely recovery of the ozone layer
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Challenges for the recovery of the ozone layer
Nature Geoscience, 2019Co-Authors: Xuekun Fang, M P Chipperfield, Sunyoung Park, John S Daniel, John A. Pyle, Ronald G. PrinnAbstract:The recovery of stratospheric ozone from past depletion is underway owing to the 1987 Montreal Protocol and its subsequent amendments, which have been effective in phasing out the production and consumption of the major ozone-depleting substances (ODSs). However, there is uncertainty about the future rate of recovery. This uncertainty relates partly to unexpected emissions of controlled anthropogenic ODSs such as CCl_3F and slower-than-expected declines in atmospheric CCl_4. A further uncertainty surrounds emissions of uncontrolled short-lived anthropogenic ODSs (such as CH_2Cl_2 and CHCl_3), which observations show have been increasing in the atmosphere through 2017, as well as potential emission increases in natural ODSs (such as CH_3Cl and CH_3Br) induced by climate change, changes in atmospheric concentrations of greenhouse gases N_2O and CH_4, and stratospheric geoengineering. These challenges could delay the return of stratospheric ozone levels to historical values, (for example, the abundance in 1980), by up to decades, depending on the future evolution of the emissions and other influencing factors. To mitigate the threats to future ozone recovery, it is crucial to ensure that the Montreal Protocol and its amendments continue to be implemented effectively in order to have firm control on future levels of ODSs. This action needs to be supported by an expansion of the geographic coverage of atmospheric observations of ODSs, by enhancing the ability of source attribution modelling, and by improving understanding of the interactions between climate change and ozone recovery. Recovery of the stratospheric ozone layer above Antarctica has not been straightforward, as a result of human activities and climate change. The recovery process might be delayed by up to decades if further mitigation actions are not taken.
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Challenges for the recovery of the ozone layer
'Springer Science and Business Media LLC', 2019Co-Authors: Fang X, M P Chipperfield, J S Daniel, Ja Pyle, Park S, Ronald G. PrinnAbstract:The recovery of stratospheric ozone from past depletion is underway owing to the 1987 Montreal Protocol and its subsequent amendments, which have been effective in phasing out the production and consumption of the major ozone-depleting substances (ODSs). However, there is uncertainty about the future rate of recovery. This uncertainty relates partly to unexpected emissions of controlled anthropogenic ODSs such as CCl₃F and slower-than-expected declines in atmospheric CCl₄. A further uncertainty surrounds emissions of uncontrolled short-lived anthropogenic ODSs (such as CH₂Cl₂ and CHCl₃), which observations show have been increasing in the atmosphere through 2017, as well as potential emission increases in natural ODSs (such as CH₃Cl and CH₃Br) induced by climate change, changes in atmospheric concentrations of greenhouse gases N₂O and CH₄, and stratospheric geoengineering. These challenges could delay the return of stratospheric ozone levels to historical values, (for example, the abundance in 1980), by up to decades, depending on the future evolution of the emissions and other influencing factors. To mitigate the threats to future ozone recovery, it is crucial to ensure that the Montreal Protocol and its amendments continue to be implemented effectively in order to have firm control on future levels of ODSs. This action needs to be supported by an expansion of the geographic coverage of atmospheric observations of ODSs, by enhancing the ability of source attribution modelling, and by improving understanding of the interactions between climate change and ozone recovery
Sandip Dhomse - One of the best experts on this subject based on the ideXlab platform.
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arctic ozone depletion in 2019 20 roles of chemistry dynamics and the Montreal Protocol
Geophysical Research Letters, 2021Co-Authors: Wuhu Feng, Sandip Dhomse, M Weber, Carlo Arosio, J P Burrows, M L Santee, M P ChipperfieldAbstract:We use a 3‐D chemical transport model and satellite observations to investigate Arctic ozone depletion in winter/spring 2019/20 and compare with earlier years. Persistently low temperatures caused extensive chlorine activation through to March. March‐mean polar‐cap‐mean modelled chemical column ozone loss reached 78 DU (local maximum loss of ∼108 DU in the vortex), similar to that in 2011. However, weak dynamical replenishment of only 59 DU from December to March was key to producing very low (<220 DU) column ozone values. The only other winter to exhibit such weak transport in the past 20 years was 2010/11, so this process is fundamental to causing such low ozone values. A model simulation with peak observed stratospheric total chlorine and bromine loading (from the mid‐1990s) shows that gradual recovery of the ozone layer over the past two decades ameliorated the polar cap ozone depletion in March 2020 by ∼20 DU.
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Arctic ozone depletion in 2019/20: Roles of chemistry, dynamics and the Montreal Protocol
'American Geophysical Union (AGU)', 2021Co-Authors: Feng W, Sandip Dhomse, J P Burrows, M L Santee, Arosio C, Weber M, Mp ChipperfieldAbstract:We use a 3‐D chemical transport model and satellite observations to investigate Arctic ozone depletion in winter/spring 2019/20 and compare with earlier years. Persistently low temperatures caused extensive chlorine activation through to March. March‐mean polar‐cap‐mean modelled chemical column ozone loss reached 78 DU (local maximum loss of ∼108 DU in the vortex), similar to that in 2011. However, weak dynamical replenishment of only 59 DU from December to March was key to producing very low (
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Fifteen Years of HFC-134a Satellite Observations: Comparisons With SLIMCAT Calculations
2021Co-Authors: Jeremy J Harrison, M P Chipperfield, Sandip Dhomse, Christopher D Boone, Peter F BernathAbstract:The phase out of anthropogenic ozone-depleting substances such as chlorofluorocarbons under the terms of the Montreal Protocol led to the development and worldwide use of hydrofluorocarbons (HFCs) in refrigeration, air conditioning, and as blowing agents and propellants. Consequently, over recent years, the atmospheric abundances of HFCs have dramatically increased. HFCs are powerful greenhouse gases and are now controlled under the terms of the 2016 Kigali Amendment to the Montreal Protocol. HFC-134a is currently the most abundant HFC in the atmosphere, breaking the 100 ppt barrier in 2018, and can be measured in the Earth's atmosphere by the satellite remote-sensing instrument ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer), which has been measuring since 2004. This work uses the ACE-FTS v4.0 data product to investigate global distributions and trends of HFC-134a. These measurements are compared with a simulation of SLIMCAT, a state-of-the-art three-dimensional chemical transport model, which is constrained by global surface HFC-134a measurements. The agreement between observation and model is good, although in the tropical troposphere ACE-FTS measurements are biased low by up to 10–15 ppt. The overall ACE-FTS global trend of HFC-134a for the altitude range 5.5–24.5 km and 2004–2018 time period is approximately linear with a value of 4.49 ± 0.02 ppt/year, slightly lower than the corresponding SLIMCAT trend of 4.66 ppt/year. Using a simple box model, we also estimate the annual global emissions and burdens of HFC-134a from the model data, indicating that emissions of HFC-134a have increased almost linearly, reaching 236 Gg by 2018
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detecting recovery of the stratospheric ozone layer
Nature, 2017Co-Authors: M P Chipperfield, Slimane Bekki, Sandip Dhomse, N R P Harris, Birgit Hassler, Ryan Hossaini, Wolfgang Steinbrecht, Remi Thieblemont, M WeberAbstract:As a result of the 1987 Montreal Protocol and its amendments, the atmospheric loading of anthropogenic ozone-depleting substances is decreasing. Accordingly, the stratospheric ozone layer is expected to recover. However, short data records and atmospheric variability confound the search for early signs of recovery, and climate change is masking ozone recovery from ozone-depleting substances in some regions and will increasingly affect the extent of recovery. Here we discuss the nature and timescales of ozone recovery, and explore the extent to which it can be currently detected in different atmospheric regions.
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The increasing threat to stratospheric ozone from dichloromethane
Nature Communications, 2017Co-Authors: Ryan Hossaini, M P Chipperfield, Sandip Dhomse, Sa Montzka, Amber Leeson, John A. PyleAbstract:It is well established that anthropogenic chlorine-containing chemicals contribute to ozone layer depletion. The successful implementation of the Montreal Protocol has led to reductions in the atmospheric concentration of many ozone-depleting gases, such as chlorofluorocarbons. As a consequence, stratospheric chlorine levels are declining and ozone is projected to return to levels observed pre-1980 later this century. However, recent observations show the atmospheric concentration of dichloromethane—an ozone-depleting gas not controlled by the Montreal Protocol—is increasing rapidly. Using atmospheric model simulations, we show that although currently modest, the impact of dichloromethane on ozone has increased markedly in recent years and if these increases continue into the future, the return of Antarctic ozone to pre-1980 levels could be substantially delayed. Sustained growth in dichloromethane would therefore offset some of the gains achieved by the Montreal Protocol, further delaying recovery of Earth’s ozone layer.
Sa Montzka - One of the best experts on this subject based on the ideXlab platform.
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Renewed and emerging concerns over the production and emission of ozone-depleting substances
'Springer Science and Business Media LLC', 2020Co-Authors: M P Chipperfield, Hossaini R, Sa Montzka, Reimann S, Sherry D, Tegtmeier SAbstract:Stratospheric ozone depletion, first observed in the 1980s, has been caused by the increased production and use of substances such as chlorofluorocarbons (CFCs), halons and other chlorine-containing and bromine-containing compounds, collectively termed ozone-depleting substances (ODSs). Following controls on the production of major, long-lived ODSs by the Montreal Protocol, the ozone layer is now showing initial signs of recovery and is anticipated to return to pre-depletion levels in the mid-to-late twenty-first century, likely 2050–2060. These return dates assume widespread compliance with the Montreal Protocol and, thereby, continued reductions in ODS emissions. However, recent observations reveal increasing emissions of some controlled (for example, CFC-11, as in eastern China) and uncontrolled substances (for example, very short-lived substances (VSLSs)). Indeed, the emissions of a number of uncontrolled VSLSs are adding significant amounts of ozone-depleting chlorine to the atmosphere. In this Review, we discuss recent emissions of both long-lived ODSs and halogenated VSLSs, and how these might lead to a delay in ozone recovery. Continued improvements in observational tools and modelling approaches are needed to assess these emerging challenges to a timely recovery of the ozone layer
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an unexpected and persistent increase in global emissions of ozone depleting cfc 11
Nature, 2018Co-Authors: Sa Montzka, John S Daniel, R W Portmann, L J M Kuijpers, G S Dutton, Eric A Ray, Brad D Hall, D J MondeelAbstract:The Montreal Protocol was designed to protect the stratospheric ozone layer by enabling reductions in the abundance of ozone-depleting substances such as chlorofluorocarbons (CFCs) in the atmosphere1–3. The reduction in the atmospheric concentration of trichlorofluoromethane (CFC-11) has made the second-largest contribution to the decline in the total atmospheric concentration of ozone-depleting chlorine since the 1990s 1 . However, CFC-11 still contributes one-quarter of all chlorine reaching the stratosphere, and a timely recovery of the stratospheric ozone layer depends on a sustained decline in CFC-11 concentrations 1 . Here we show that the rate of decline of atmospheric CFC-11 concentrations observed at remote measurement sites was constant from 2002 to 2012, and then slowed by about 50 per cent after 2012. The observed slowdown in the decline of CFC-11 concentration was concurrent with a 50 per cent increase in the mean concentration difference observed between the Northern and Southern Hemispheres, and also with the emergence of strong correlations at the Mauna Loa Observatory between concentrations of CFC-11 and other chemicals associated with anthropogenic emissions. A simple model analysis of our findings suggests an increase in CFC-11 emissions of 13 ± 5 gigagrams per year (25 ± 13 per cent) since 2012, despite reported production being close to zero 4 since 2006. Our three-dimensional model simulations confirm the increase in CFC-11 emissions, but indicate that this increase may have been as much as 50 per cent smaller as a result of changes in stratospheric processes or dynamics. The increase in emission of CFC-11 appears unrelated to past production; this suggests unreported new production, which is inconsistent with the Montreal Protocol agreement to phase out global CFC production by 2010.
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The increasing threat to stratospheric ozone from dichloromethane
Nature Communications, 2017Co-Authors: Ryan Hossaini, M P Chipperfield, Sandip Dhomse, Sa Montzka, Amber Leeson, John A. PyleAbstract:It is well established that anthropogenic chlorine-containing chemicals contribute to ozone layer depletion. The successful implementation of the Montreal Protocol has led to reductions in the atmospheric concentration of many ozone-depleting gases, such as chlorofluorocarbons. As a consequence, stratospheric chlorine levels are declining and ozone is projected to return to levels observed pre-1980 later this century. However, recent observations show the atmospheric concentration of dichloromethane—an ozone-depleting gas not controlled by the Montreal Protocol—is increasing rapidly. Using atmospheric model simulations, we show that although currently modest, the impact of dichloromethane on ozone has increased markedly in recent years and if these increases continue into the future, the return of Antarctic ozone to pre-1980 levels could be substantially delayed. Sustained growth in dichloromethane would therefore offset some of the gains achieved by the Montreal Protocol, further delaying recovery of Earth’s ozone layer.
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increase in hfc 134a emissions in response to the success of the Montreal Protocol
Journal of Geophysical Research, 2015Co-Authors: Sa Montzka, Audrey Fortemscheiney, Marielle Saunois, I Pison, Frederic Chevallier, P J Bousquet, C Cressot, P J Fraser, Martin K. VollmerAbstract:Author(s): Fortems-Cheiney, A; Saunois, M; Pison, I; Chevallier, F; Bousquet, P; Cressot, C; Montzka, SA; Fraser, PJ; Vollmer, MK; Simmonds, PG; Young, D; O'Doherty, S; Weiss, RF; Artuso, F; Barletta, B; Blake, DR; Li, S; Lunder, C; Miller, BR; Park, S; Prinn, R; Saito, T; Steele, LP; Yokouchi, Y | Abstract: ©2015. American Geophysical Union. 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 8day) resolution, using surface HFC-134a measurements. Our results show a progressive increase of global HFC-134a emissions from 19±2Gg/yr in 1995 to 167±5Gg/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.
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efficiency of short lived halogens at influencing climate through depletion of stratospheric ozone
Nature Geoscience, 2015Co-Authors: Ryan Hossaini, Mp Chipperfield, Sandip Dhomse, Sa Montzka, A Rap, Wuhu FengAbstract:Short-lived halogens are produced naturally and anthropogenically, and are not governed by the Montreal Protocol. Like halocarbons, short-lived halogens destroy lower-stratospheric ozone, resulting in a net cooling effect since pre-industrial times.
John S Daniel - One of the best experts on this subject based on the ideXlab platform.
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Challenges for the recovery of the ozone layer
Nature Geoscience, 2019Co-Authors: Xuekun Fang, M P Chipperfield, Sunyoung Park, John S Daniel, John A. Pyle, Ronald G. PrinnAbstract:The recovery of stratospheric ozone from past depletion is underway owing to the 1987 Montreal Protocol and its subsequent amendments, which have been effective in phasing out the production and consumption of the major ozone-depleting substances (ODSs). However, there is uncertainty about the future rate of recovery. This uncertainty relates partly to unexpected emissions of controlled anthropogenic ODSs such as CCl_3F and slower-than-expected declines in atmospheric CCl_4. A further uncertainty surrounds emissions of uncontrolled short-lived anthropogenic ODSs (such as CH_2Cl_2 and CHCl_3), which observations show have been increasing in the atmosphere through 2017, as well as potential emission increases in natural ODSs (such as CH_3Cl and CH_3Br) induced by climate change, changes in atmospheric concentrations of greenhouse gases N_2O and CH_4, and stratospheric geoengineering. These challenges could delay the return of stratospheric ozone levels to historical values, (for example, the abundance in 1980), by up to decades, depending on the future evolution of the emissions and other influencing factors. To mitigate the threats to future ozone recovery, it is crucial to ensure that the Montreal Protocol and its amendments continue to be implemented effectively in order to have firm control on future levels of ODSs. This action needs to be supported by an expansion of the geographic coverage of atmospheric observations of ODSs, by enhancing the ability of source attribution modelling, and by improving understanding of the interactions between climate change and ozone recovery. Recovery of the stratospheric ozone layer above Antarctica has not been straightforward, as a result of human activities and climate change. The recovery process might be delayed by up to decades if further mitigation actions are not taken.
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an unexpected and persistent increase in global emissions of ozone depleting cfc 11
Nature, 2018Co-Authors: Sa Montzka, John S Daniel, R W Portmann, L J M Kuijpers, G S Dutton, Eric A Ray, Brad D Hall, D J MondeelAbstract:The Montreal Protocol was designed to protect the stratospheric ozone layer by enabling reductions in the abundance of ozone-depleting substances such as chlorofluorocarbons (CFCs) in the atmosphere1–3. The reduction in the atmospheric concentration of trichlorofluoromethane (CFC-11) has made the second-largest contribution to the decline in the total atmospheric concentration of ozone-depleting chlorine since the 1990s 1 . However, CFC-11 still contributes one-quarter of all chlorine reaching the stratosphere, and a timely recovery of the stratospheric ozone layer depends on a sustained decline in CFC-11 concentrations 1 . Here we show that the rate of decline of atmospheric CFC-11 concentrations observed at remote measurement sites was constant from 2002 to 2012, and then slowed by about 50 per cent after 2012. The observed slowdown in the decline of CFC-11 concentration was concurrent with a 50 per cent increase in the mean concentration difference observed between the Northern and Southern Hemispheres, and also with the emergence of strong correlations at the Mauna Loa Observatory between concentrations of CFC-11 and other chemicals associated with anthropogenic emissions. A simple model analysis of our findings suggests an increase in CFC-11 emissions of 13 ± 5 gigagrams per year (25 ± 13 per cent) since 2012, despite reported production being close to zero 4 since 2006. Our three-dimensional model simulations confirm the increase in CFC-11 emissions, but indicate that this increase may have been as much as 50 per cent smaller as a result of changes in stratospheric processes or dynamics. The increase in emission of CFC-11 appears unrelated to past production; this suggests unreported new production, which is inconsistent with the Montreal Protocol agreement to phase out global CFC production by 2010.
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future atmospheric abundances and climate forcings from scenarios of global and regional hydrofluorocarbon hfc emissions
Atmospheric Environment, 2015Co-Authors: Guus J. M. Velders, Stephen O Andersen, John S Daniel, D W Fahey, Mack McfarlandAbstract:Hydrofluorocarbons (HFCs) are manufactured for use as substitutes for ozone-depleting substances that are being phased out globally under Montreal Protocol regulations. While HFCs do not deplete ozone, many are potent greenhouse gases that contribute to climate change. Here, new global scenarios show that baseline emissions of HFCs could reach 4.0–5.3 GtCO2-eq yr−1 in 2050. The new baseline (or business-as-usual) scenarios are formulated for 10 HFC compounds, 11 geographic regions, and 13 use categories. The scenarios rely on detailed data reported by countries to the United Nations; projections of gross domestic product and population; and recent observations of HFC atmospheric abundances. In the baseline scenarios, by 2050 China (31%), India and the rest of Asia (23%), the Middle East and northern Africa (11%), and the USA (10%) are the principal source regions for global HFC emissions; and refrigeration (40–58%) and stationary air conditioning (21–40%) are the major use sectors. The corresponding radiative forcing could reach 0.22–0.25 W m−2 in 2050, which would be 12–24% of the increase from business-as-usual CO2 emissions from 2015 to 2050. National regulations to limit HFC use have already been adopted in the European Union, Japan and USA, and proposals have been submitted to amend the Montreal Protocol to substantially reduce growth in HFC use. Calculated baseline emissions are reduced by 90% in 2050 by implementing the North America Montreal Protocol amendment proposal. Global adoption of technologies required to meet national regulations would be sufficient to reduce 2050 baseline HFC consumption by more than 50% of that achieved with the North America proposal for most developed and developing countries.
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nitrous oxide n2o the dominant ozone depleting substance emitted in the 21st century
Science, 2009Co-Authors: A R Ravishankara, John S Daniel, R W PortmannAbstract:By comparing the ozone depletion potential-weighted anthropogenic emissions of N2O with those of other ozone-depleting substances, we show that N2O emission currently is the single most important ozone-depleting emission and is expected to remain the largest throughout the 21st century. N2O is unregulated by the Montreal Protocol. Limiting future N2O emissions would enhance the recovery of the ozone layer from its depleted state and would also reduce the anthropogenic forcing of the climate system, representing a win-win for both ozone and climate.
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estimates of ozone depletion and skin cancer incidence to examine the vienna convention achievements
Nature, 1996Co-Authors: H Slaper, John S Daniel, Guus J. M. Velders, Frank R De Gruijl, Jan C Van Der LeunAbstract:DEPLETION of the ozone layer has been observed on a global scale1, and is probably related to halocarbon emissions. Ozone depletion increases the biologically harmful solar ultraviolet radiation reaching the surface of the Earth, which leads to a variety of adverse effects, including an increase in the incidence of skin cancer. The 1985 Vienna Convention provided the framework for international restrictions on the production of ozone-depleting substances. The consequences of such restrictions have not yet been assessed in terms of effects avoided. Here we present a new method of estimating future excess skin cancer risks which is used to compare effects of a 'no restrictions' scenario with two restrictive scenarios specified under the Vienna Convention: the Montreal Protocol, and the much stricter Copenhagen Amendments. The no-restrictions and Montreal Protocol scenarios produce a runaway increase in skin cancer incidence, up to a quadrupling and doubling, respectively, by the year 2100. The Copenhagen Amendments scenario leads to an ozone minimum around the year 2000, and a peak relative increase in incidence of skin cancer of almost 10% occurring 60 years later. These results demonstrate the importance of the international measures agreed upon under the Vienna Convention.
Ronald G. Prinn - One of the best experts on this subject based on the ideXlab platform.
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Challenges for the recovery of the ozone layer
Nature Geoscience, 2019Co-Authors: Xuekun Fang, M P Chipperfield, Sunyoung Park, John S Daniel, John A. Pyle, Ronald G. PrinnAbstract:The recovery of stratospheric ozone from past depletion is underway owing to the 1987 Montreal Protocol and its subsequent amendments, which have been effective in phasing out the production and consumption of the major ozone-depleting substances (ODSs). However, there is uncertainty about the future rate of recovery. This uncertainty relates partly to unexpected emissions of controlled anthropogenic ODSs such as CCl_3F and slower-than-expected declines in atmospheric CCl_4. A further uncertainty surrounds emissions of uncontrolled short-lived anthropogenic ODSs (such as CH_2Cl_2 and CHCl_3), which observations show have been increasing in the atmosphere through 2017, as well as potential emission increases in natural ODSs (such as CH_3Cl and CH_3Br) induced by climate change, changes in atmospheric concentrations of greenhouse gases N_2O and CH_4, and stratospheric geoengineering. These challenges could delay the return of stratospheric ozone levels to historical values, (for example, the abundance in 1980), by up to decades, depending on the future evolution of the emissions and other influencing factors. To mitigate the threats to future ozone recovery, it is crucial to ensure that the Montreal Protocol and its amendments continue to be implemented effectively in order to have firm control on future levels of ODSs. This action needs to be supported by an expansion of the geographic coverage of atmospheric observations of ODSs, by enhancing the ability of source attribution modelling, and by improving understanding of the interactions between climate change and ozone recovery. Recovery of the stratospheric ozone layer above Antarctica has not been straightforward, as a result of human activities and climate change. The recovery process might be delayed by up to decades if further mitigation actions are not taken.
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china s hydrofluorocarbon emissions for 2011 2017 inferred from atmospheric measurements
Environmental Science and Technology Letters, 2019Co-Authors: Bo Yao, Xuekun Fang, Martin K. Vollmer, Stefan Reimann, Liqu Chen, Shuangxi Fang, Ronald G. PrinnAbstract:Hydrofluorocarbons (HFCs) have been widely used in China to replace ozone-depleting substances (ODSs) that must be phased out under the Montreal Protocol. Few studies have reported on HFC emissions...
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Challenges for the recovery of the ozone layer
'Springer Science and Business Media LLC', 2019Co-Authors: Fang X, M P Chipperfield, J S Daniel, Ja Pyle, Park S, Ronald G. PrinnAbstract:The recovery of stratospheric ozone from past depletion is underway owing to the 1987 Montreal Protocol and its subsequent amendments, which have been effective in phasing out the production and consumption of the major ozone-depleting substances (ODSs). However, there is uncertainty about the future rate of recovery. This uncertainty relates partly to unexpected emissions of controlled anthropogenic ODSs such as CCl₃F and slower-than-expected declines in atmospheric CCl₄. A further uncertainty surrounds emissions of uncontrolled short-lived anthropogenic ODSs (such as CH₂Cl₂ and CHCl₃), which observations show have been increasing in the atmosphere through 2017, as well as potential emission increases in natural ODSs (such as CH₃Cl and CH₃Br) induced by climate change, changes in atmospheric concentrations of greenhouse gases N₂O and CH₄, and stratospheric geoengineering. These challenges could delay the return of stratospheric ozone levels to historical values, (for example, the abundance in 1980), by up to decades, depending on the future evolution of the emissions and other influencing factors. To mitigate the threats to future ozone recovery, it is crucial to ensure that the Montreal Protocol and its amendments continue to be implemented effectively in order to have firm control on future levels of ODSs. This action needs to be supported by an expansion of the geographic coverage of atmospheric observations of ODSs, by enhancing the ability of source attribution modelling, and by improving understanding of the interactions between climate change and ozone recovery
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Changes in Emissions of Ozone-Depleting Substances from China Due to Implementation of the Montreal Protocol
2018Co-Authors: Xuekun Fang, Mario J Molina, A R Ravishankara, Guus J. M. Velders, Jianbo Zhang, Ronald G. PrinnAbstract:The ozone layer depletion and its recovery, as well as the climate influence of ozone-depleting substances (ODSs) and their substitutes that influence climate, are of interest to both the scientific community and the public. Here we report on the emissions of ODSs and their substitute from China, which is currently the largest consumer (and emitter) of these substances. We provide, for the first time, comprehensive information on ODSs and replacement hydrofluorocarbon (HFC) emissions in China starting from 1980 based on reported production and usage. We also assess the impacts (and costs) of controls on ODS consumption and emissions on the ozone layer (in terms of CFC-11-equivalent) and climate (in CO2-equivalent). In addition, we show that while China’s future ODS emissions are likely to be defined as long as there is full compliance with the Montreal Protocol; its HFC emissions through 2050 are very uncertain. Our findings imply that HFC controls over the next decades that are more stringent than those under the Kigali Amendment to the Montreal Protocol would be beneficial in mitigating global climate change
