Contributions to stratospheric ozone changes from ozone depleting substances and greenhouse gases

Abstract. A state-of-the-art chemistry climate model coupled to a three-dimensional ocean model is used to produce three experiments, all seamlessly covering the period 1950–2100, forced by different combinations of long-lived Greenhouse Gases (GHGs) and Ozone Depleting Substances (ODSs). The experiments are designed to investigate the mechanisms by which GHGs and ODSs affect the evolution of ozone, including changes in the Brewer-Dobson circulation of the stratosphere and cooling of the upper stratosphere by CO2. Separating the effects of GHGs and ODSs on ozone, we find the decrease in upper stratospheric ozone from ODSs up to the year 2000 is approximately 30% larger than the actual decrease in ozone due to the offsetting effects of cooling by increased CO2. Over the 21st century, as ODSs decrease, continued cooling from CO2 is projected to account for more than 50% of the projected increase in upper stratospheric ozone. Changes below 20 hPa show a redistribution of ozone from tropical to extra-tropical latitudes with an increase in the Brewer-Dobson circulation, while globally averaged the amount of ozone below 20 hPa decreases over the 21st century. Further analysis by linear regression shows that changes associated with GHGs do not appreciably alter the recovery of stratospheric ozone from the effects of ODSs; over much of the stratosphere ozone recovery follows the decline of halogen concentrations within statistical uncertainty, though the lower polar stratosphere of the Southern Hemisphere is an exception with ozone concentrations recovering more slowly than indicated by the halogen concentrations. These results also reveal the degree to which climate change, and stratospheric CO2 cooling in particular, mutes the chemical effects of N2O on ozone in the standard future scenario used for the WMO Ozone Assessment. Increases in the residual circulation of the atmosphere and chemical effects from CO2 cooling more than halve the increase in reactive nitrogen in the mid to upper stratosphere that results from the specified increase in N2O between 1950 and 2100.

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Quantifying the contributions to stratospheric ozone changes from ozone depleting substances and greenhouse gases

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-8803-2010 ◽

2010 ◽

Vol 10 (18) ◽

pp. 8803-8820 ◽

Cited By ~ 29

Author(s):

D. A. Plummer ◽

J. F. Scinocca ◽

T. G. Shepherd ◽

M. C. Reader ◽

A. I. Jonsson

Keyword(s):

Greenhouse Gases ◽

21St Century ◽

Climate Model ◽

Stratospheric Ozone ◽

Three Dimensional ◽

Ocean Model ◽

Residual Circulation ◽

Total Column Ozone ◽

Chemical Effects ◽

Ozone Depleting Substances

Abstract. A state-of-the-art chemistry climate model coupled to a three-dimensional ocean model is used to produce three experiments, all seamlessly covering the period 1950–2100, forced by different combinations of long-lived Greenhouse Gases (GHGs) and Ozone Depleting Substances (ODSs). The experiments are designed to quantify the separate effects of GHGs and ODSs on the evolution of ozone, as well as the extent to which these effects are independent of each other, by alternately holding one set of these two forcings constant in combination with a third experiment where both ODSs and GHGs vary. We estimate that up to the year 2000 the net decrease in the column amount of ozone above 20 hPa is approximately 75% of the decrease that can be attributed to ODSs due to the offsetting effects of cooling by increased CO2. Over the 21st century, as ODSs decrease, continued cooling from CO2 is projected to account for more than 50% of the projected increase in ozone above 20 hPa. Changes in ozone below 20 hPa show a redistribution of ozone from tropical to extra-tropical latitudes with an increase in the Brewer-Dobson circulation. In addition to a latitudinal redistribution of ozone, we find that the globally averaged column amount of ozone below 20 hPa decreases over the 21st century, which significantly mitigates the effect of upper stratospheric cooling on total column ozone. Analysis by linear regression shows that the recovery of ozone from the effects of ODSs generally follows the decline in reactive chlorine and bromine levels, with the exception of the lower polar stratosphere where recovery of ozone in the second half of the 21st century is slower than would be indicated by the decline in reactive chlorine and bromine concentrations. These results also reveal the degree to which GHG-related effects mute the chemical effects of N2O on ozone in the standard future scenario used for the WMO Ozone Assessment. Increases in the residual circulation of the atmosphere and chemical effects from CO2 cooling more than halve the increase in reactive nitrogen in the mid to upper stratosphere that results from the specified increase in N2O between 1950 and 2100.

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Key drivers of ozone change and its radiative forcing over the 21st century

10.5194/acp-2017-939 ◽

2017 ◽

Author(s):

Fernando Iglesias-Suarez ◽

Douglas E. Kinnison ◽

Alexandru Rap ◽

Oliver Wild ◽

Paul J. Young

Keyword(s):

Climate Change ◽

21St Century ◽

Radiative Forcing ◽

Climate Model ◽

Stratospheric Ozone ◽

Atmospheric Composition ◽

Radiative Balance ◽

Uncertainty Range ◽

Ozone Depleting Substances ◽

Year 2000

Abstract. Over the 21st century changes in both tropospheric and stratospheric ozone are likely to have important consequences for the Earth's radiative balance. In this study we investigated the radiative effects of future ozone changes, using the Community Earth System Model (CESM1), with the Whole Atmosphere Community Climate Model (WACCM), and including fully coupled radiation and chemistry schemes. Using year 2100 conditions from the Representative Concentration Pathways 8.5 (RCP8.5) scenario, we quantified the individual contributions to ozone radiative forcing of (1) climate change (with and without lightning feedback), (2) reduced concentrations of ozone depleting substances (ODSs), and (3) methane increases. We calculated future ozone radiative forcing relative to year 2000 of (1) 63 ± 76 m Wm−2, (2) 129 ± 81 m Wm−2, and (3) 225 ± 85 m Wm−2, due to climate change, ODSs and methane respectively. Our best estimate of net ozone forcing in this set of simulations is 420 ± 120 m Wm−2 relative to year 2000, and 750 ± 230 m Wm−2 relative to year 1750, with uncertainty range given by approximately ±30 %. We find that the overall long-term tropospheric ozone forcing from methane chemistry-climate feedbacks related to OH and methane lifetime is small (46 m Wm−2). Ozone forcings associated with climate change and stratospheric ozone recovery are robust with regard to background conditions, even though the ozone response is sensitive to both changes in atmospheric composition and climate. Changes in stratospheric-produced ozone account for ~ 47 % of the overall radiative forcing in this set of simulations, highlighting the key role of the stratosphere in determining future radiative forcing.

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Nonlinear response of modeled stratospheric ozone to changes in greenhouse gases and ozone depleting substances in the recent past

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-9253-2015 ◽

2015 ◽

Vol 15 (6) ◽

pp. 9253-9291 ◽

Cited By ~ 1

Author(s):

S. Meul ◽

S. Oberländer-Hayn ◽

J. Abalichin ◽

U. Langematz

Keyword(s):

Greenhouse Gases ◽

Climate Model ◽

Stratospheric Ozone ◽

Nonlinear Effects ◽

Polar Regions ◽

Recent Past ◽

Residual Circulation ◽

Nonlinear Processes ◽

Ozone Depleting Substances ◽

The Impact

Abstract. In the recent past, the evolution of stratospheric ozone (O3) was affected by both increasing ozone depleting substances (ODSs) and greenhouse gases (GHGs). The impact of the single forcings on O3 is well known. Interactions between the simultaneously increased GHG and ODS concentrations, however, can occur and lead to nonlinear O3 changes. In this study, we investigate if nonlinear processes have affected O3 changes between 1960 and 2000. This is done with an idealized set of timeslice simulations with the chemistry–climate model (CCM) EMAC. Nonlinearity leads to a net reduction of ozone decrease throughout the stratosphere, with a maximum of 1.2% at 3 hPa. The total ozone column loss between 1960 and 2000 that is mainly attributed to the ODS increase is mitigated in the extra-polar regions by up to 1.1% due to nonlinear processes. A separation of the O3 changes into the contribution from chemistry and transport shows that nonlinear interactions occur in both. In the upper stratosphere a reduced efficiency of the ClOx-catalysed O3 loss chiefly causes the nonlinear O3 increase. An enhanced formation of halogen reservoir species through the reaction with methane (CH4) reduces the abundance of halogen radicals significantly. The temperature induced deceleration of the O3 loss reaction rate in the Chapman cycle is reduced, which leads to a nonlinear O3 decrease and counteracts the increase due to ClOx. Nonlinear effects on the NOx abundance cause hemispheric asymmetric nonlinear changes of the O3 loss. Nonlinear changes in O3 transport occur in particular in the Southern Hemisphere (SH) during the months September to November. Here, the residual circulation is weakened in the lower stratosphere, which goes along with a reduced O3 transport from the tropics to high latitudes. Thus, O3 decreases in the SH polar region, but increases in the SH midlatitudes.

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Nonlinear response of modelled stratospheric ozone to changes in greenhouse gases and ozone depleting substances in the recent past

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-6897-2015 ◽

2015 ◽

Vol 15 (12) ◽

pp. 6897-6911 ◽

Cited By ~ 6

Author(s):

S. Meul ◽

S. Oberländer-Hayn ◽

J. Abalichin ◽

U. Langematz

Keyword(s):

Greenhouse Gases ◽

Climate Model ◽

Stratospheric Ozone ◽

Polar Regions ◽

Recent Past ◽

Residual Circulation ◽

Nonlinear Processes ◽

The Past ◽

Ozone Depleting Substances ◽

The Impact

Abstract. In the recent past, the evolution of stratospheric ozone (O3) was affected by both increasing ozone depleting substances (ODSs) and greenhouse gases (GHGs). The impact of the single forcings on O3 is well known. Interactions between the simultaneously increased GHG and ODS concentrations, however, can occur and lead to nonlinear O3 changes. In this study, we investigate if nonlinear processes have affected O3 changes between 1960 and 2000. This is done with an idealised set of time slice simulations with the chemistry-climate model EMAC. Due to nonlinearity the past ozone loss is diminished throughout the stratosphere, with a maximum reduction of 1.2 % at 3 hPa. The total ozone column loss between 1960 and 2000 that is mainly attributed to the ODS increase is mitigated in the extra-polar regions by up to 1.1 % due to nonlinear processes. A separation of the O3 changes into the contribution from chemistry and transport shows that nonlinear interactions occur in both. In the upper stratosphere a reduced efficiency of the ClOx-catalysed O3 loss chiefly causes the nonlinear O3 increase. An enhanced formation of halogen reservoir species through the reaction with methane (CH4) reduces the abundance of halogen radicals significantly. The temperature-induced deceleration of the O3 loss reaction rate in the Chapman cycle is reduced, which leads to a nonlinear O3 decrease and counteracts the increase due to ClOx. Nonlinear effects on the NOx abundance cause hemispheric asymmetric nonlinear changes of the O3 loss. Nonlinear changes in O3 transport occur in particular in the Southern Hemisphere (SH) during the months September to November. Here, the residual circulation is weakened in the lower stratosphere, which goes along with a reduced O3 transport from the tropics to high latitudes. Thus, O3 decreases in the SH polar region but increases in the SH midlatitudes. The existence of nonlinearities implies that future ozone change due to ODS decline slightly depends on the prevailing GHG concentrations. Therefore the future ozone evolution will not simply be a reversal of the past.

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Key drivers of ozone change and its radiative forcing over the 21st century

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-6121-2018 ◽

2018 ◽

Vol 18 (9) ◽

pp. 6121-6139 ◽

Cited By ~ 6

Author(s):

Fernando Iglesias-Suarez ◽

Douglas E. Kinnison ◽

Alexandru Rap ◽

Amanda C. Maycock ◽

Oliver Wild ◽

...

Keyword(s):

Climate Change ◽

21St Century ◽

Radiative Forcing ◽

Climate Model ◽

Stratospheric Ozone ◽

Atmospheric Composition ◽

Climate Conditions ◽

Radiative Balance ◽

Radiative Forcings ◽

Year 2000

Abstract. Over the 21st century changes in both tropospheric and stratospheric ozone are likely to have important consequences for the Earth's radiative balance. In this study, we investigate the radiative forcing from future ozone changes using the Community Earth System Model (CESM1), with the Whole Atmosphere Community Climate Model (WACCM), and including fully coupled radiation and chemistry schemes. Using year 2100 conditions from the Representative Concentration Pathway 8.5 (RCP8.5) scenario, we quantify the individual contributions to ozone radiative forcing of (1) climate change, (2) reduced concentrations of ozone depleting substances (ODSs), and (3) methane increases. We calculate future ozone radiative forcings and their standard error (SE; associated with inter-annual variability of ozone) relative to year 2000 of (1) 33 ± 104 m Wm−2, (2) 163 ± 109 m Wm−2, and (3) 238 ± 113 m Wm−2 due to climate change, ODSs, and methane, respectively. Our best estimate of net ozone forcing in this set of simulations is 430 ± 130 m Wm−2 relative to year 2000 and 760 ± 230 m Wm−2 relative to year 1750, with the 95 % confidence interval given by ±30 %. We find that the overall long-term tropospheric ozone forcing from methane chemistry–climate feedbacks related to OH and methane lifetime is relatively small (46 m Wm−2). Ozone radiative forcing associated with climate change and stratospheric ozone recovery are robust with regard to background climate conditions, even though the ozone response is sensitive to both changes in atmospheric composition and climate. Changes in stratospheric-produced ozone account for ∼ 50 % of the overall radiative forcing for the 2000–2100 period in this set of simulations, highlighting the key role of the stratosphere in determining future ozone radiative forcing.

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Numerical modeling of the natural and anthropogenic factors influence on the past and future changes in polar, mid-latitude and tropical ozone

10.5194/egusphere-egu2020-20440 ◽

2020 ◽

Author(s):

Sergei Smyshlyaev ◽

Polina Blakitnaya ◽

Maxim Motsakov ◽

Vener Galin

Keyword(s):

Solar Activity ◽

Greenhouse Gases ◽

Climate Model ◽

Middle Atmosphere ◽

Stratospheric Ozone ◽

Stratospheric Aerosol ◽

Anthropogenic Factors ◽

The Past ◽

Ozone Depleting Substances ◽

Natural And Anthropogenic Factors

<p>The INM RAS &#8211; RSHU chemistry-climate model of the lower and middle atmosphere is used to compare the role of natural and anthropogenic factors in the observed and expected variability of stratospheric ozone. Numerical experiments have been carried out on several scenarios of separate and combined effects of solar activity, stratospheric aerosol, sea surface temperature, greenhouse gases, and ozone-depleting substances emissions on ozone for the period from 1979 to 2050. Simulations for the past and present periods are compared to the results of ground-based and satellite observations, as well as MERRA and ERA-Interim re-analysis. Estimation of future ozone changes are based on different scenarios of changes in solar activity and emissions of ozone-depleting substances and greenhouse gases, as well as the possibility of large volcanic aerosol emissions at different periods of time.</p>

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Detectability of the Impacts of Ozone Depleting Substances and Greenhouse Gases upon Stratospheric Ozone Accounting for Nonlinearities in Historical Forcings

10.5194/acp-2017-585 ◽

2017 ◽

Author(s):

Justin Bandoro ◽

Susan Solomon ◽

Benajmin D. Santer ◽

Douglas E. Kinnison ◽

Michael J. Mills

Keyword(s):

Greenhouse Gases ◽

Climate Model ◽

Linear Trend ◽

Stratospheric Ozone ◽

Global Changes ◽

Response Patterns ◽

Pattern Similarity ◽

Ozone Depleting Substances ◽

The Individual ◽

Observational Record

Abstract. We perform a formal attribution study of upper and lower stratospheric ozone changes using observations together with simulations from the Whole Atmosphere Community Climate Model. Historical model simulations were used to estimate the zonal-mean response patterns (fingerprints) to combined forcing by ozone depleting substances (ODS) and well-mixed greenhouse gases (GHG), as well as to the individual forcing by each factor. Trends in the similarity between the searched-for fingerprints and homogenized observations of stratospheric ozone were compared to trends in pattern similarity between the fingerprints and the internally and naturally generated variability inferred from long control runs. This yields estimated signal-to-noise (S/N) ratios for each of the three fingerprints (ODS, GHG, and ODS+GHG). In both the upper stratosphere (defined in this paper as 1 to 10 hPa) and lower stratosphere (40 to 100 hPa), the spatial fingerprints of the ODS+GHG and ODS only patterns were consistently detectable not only during the era of maximum ozone depletion, but also throughout the observational record (1984–2016). Furthermore, we develop a fingerprint attribution method to account for forcings whose time evolutions are markedly nonlinear over the observational record. When the nonlinearity of the time evolution of the ODS and ODS+GHG signals are used in the trend regression, we find that the S/N ratios obtained with the stratospheric ODS and ODS+GHG fingerprints are enhanced relative to standard linear trend analysis. With this method, the complete observational record can be used in the S/N analysis, without applying piece-wise linear regression and introducing arbitrary break points. The GHG-driven fingerprint of ozone changes was not statistically identifiable in the either the upper or lower stratospheric SWOOSH data, irrespective of the method used. Use of the nonlinear signal method, instead of directly operating on ozone trends, also reduces the detection time – the estimate of the date at which ODS and GHG impacts on ozone can be formally identified. In the WACCM future simulations, the GHG signal is statistically identifiable between 2020–2030. Our findings demonstrate the importance of continued stratospheric ozone monitoring to improve estimates of the contributions of ODS and GHG forcing to global changes in stratospheric ozone.

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Comment on "Tropospheric temperature response to stratospheric ozone recovery in the 21st century" by Hu et al. (2011)

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-2533-2012 ◽

2012 ◽

Vol 12 (5) ◽

pp. 2533-2540 ◽

Cited By ~ 8

Author(s):

C. McLandress ◽

J. Perlwitz ◽

T. G. Shepherd

Keyword(s):

Northern Hemisphere ◽

Climate Models ◽

Climate Model ◽

Stratospheric Ozone ◽

Three Dimensional ◽

Temperature Response ◽

Ocean Model ◽

Tropospheric Temperature ◽

Cmip3 Model ◽

Incomplete Removal

Abstract. In a recent paper Hu et al. (2011) suggest that the recovery of stratospheric ozone during the first half of this century will significantly enhance free tropospheric and surface warming caused by the anthropogenic increase of greenhouse gases, with the effects being most pronounced in Northern Hemisphere middle and high latitudes. These surprising results are based on a multi-model analysis of CMIP3 model simulations with and without prescribed stratospheric ozone recovery. Hu et al. suggest that in order to properly quantify the tropospheric and surface temperature response to stratospheric ozone recovery, it is necessary to run coupled atmosphere-ocean climate models with stratospheric ozone chemistry. The results of such an experiment are presented here, using a state-of-the-art chemistry-climate model coupled to a three-dimensional ocean model. In contrast to Hu et al., we find a much smaller Northern Hemisphere tropospheric temperature response to ozone recovery, which is of opposite sign. We suggest that their result is an artifact of the incomplete removal of the large effect of greenhouse gas warming between the two different sets of models.

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On the attribution of stratospheric ozone and temperature changes to changes in ozone-depleting substances and well-mixed greenhouse gases

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-1435-2008 ◽

2008 ◽

Vol 8 (5) ◽

pp. 1435-1444 ◽

Cited By ~ 49

Author(s):

T. G. Shepherd ◽

A. I. Jonsson

Keyword(s):

Climate Model ◽

Traditional Approach ◽

Stratospheric Ozone ◽

Three Dimensional ◽

Order Effect ◽

Temperature Changes ◽

Stratospheric Temperature ◽

Cooling Effects ◽

Ozone Depleting Substances ◽

Global Mean

Abstract. The vertical profile of global-mean stratospheric temperature changes has traditionally represented an important diagnostic for the attribution of the cooling effects of stratospheric ozone depletion and CO2 increases. However, CO2-induced cooling alters ozone abundance by perturbing ozone chemistry, thereby coupling the stratospheric ozone and temperature responses to changes in CO2 and ozone-depleting substances (ODSs). Here we untangle the ozone-temperature coupling and show that the attribution of global-mean stratospheric temperature changes to CO2 and ODS changes (which are the true anthropogenic forcing agents) can be quite different from the traditional attribution to CO2 and ozone changes. The significance of these effects is quantified empirically using simulations from a three-dimensional chemistry-climate model. The results confirm the essential validity of the traditional approach in attributing changes during the past period of rapid ODS increases, although we find that about 10% of the upper stratospheric ozone decrease from ODS increases over the period 1975–1995 was offset by the increase in CO2, and the CO2-induced cooling in the upper stratosphere has been somewhat overestimated. When considering ozone recovery, however, the ozone-temperature coupling is a first-order effect; fully 2/5 of the upper stratospheric ozone increase projected to occur from 2010–2040 is attributable to CO2 increases. Thus, it has now become necessary to base attribution of global-mean stratospheric temperature changes on CO2 and ODS changes rather than on CO2 and ozone changes.

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Quantifying uncertainty in projections of stratospheric ozone over the 21st century

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-11915-2010 ◽

2010 ◽

Vol 10 (5) ◽

pp. 11915-11950 ◽

Cited By ~ 2

Author(s):

A. J. Charlton-Perez ◽

E. Hawkins ◽

V. Eyring ◽

I. Cionni ◽

G. E. Bodeker ◽

...

Keyword(s):

21St Century ◽

Climate Model ◽

Stratospheric Ozone ◽

Internal Variability ◽

Climate Modelling ◽

Ozone Concentrations ◽

Geographical Regions ◽

Scenario Uncertainty ◽

Ozone Depleting Substances ◽

Future Economic Development

Abstract. Future stratospheric ozone concentrations will be determined both by changes in the concentration of ozone depleting substances (ODSs) and by changes in stratospheric and tropospheric climate, including those caused by changes in anthropogenic greenhouse gases (GHGs). Since future economic development pathways and resultant emissions of GHGs are uncertain, anthropogenic climate change could be a significant source of uncertainty for future projections of stratospheric ozone. In this pilot study, using an "ensemble of opportunity" of chemistry-climate model (CCM) simulations, the contribution of scenario uncertainty from different plausible emissions pathways for ODSs and GHGs to future ozone projections is quantified relative to the contribution from model uncertainty and internal variability of the chemistry-climate system. For both the global, annual mean ozone concentration and for ozone in specific geographical regions, differences between CCMs are the dominant source of uncertainty for the first two-thirds of the 21st century, up-to and after the time when ozone concentrations return to 1980 values. In the last third of the 21st century, dependent upon the set of greenhouse gas scenarios used, scenario uncertainty can be the dominant contributor. This result suggests that investment in chemistry-climate modelling is likely to continue to refine projections of stratospheric ozone and estimates of the return of stratospheric ozone concentrations to pre-1980 levels.

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