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

2010 ◽  
Vol 10 (5) ◽  
pp. 11915-11950 ◽  
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.

scholarly journals The potential to narrow uncertainty in projections of stratospheric ozone over the 21st century

2010 ◽  
Vol 10 (19) ◽  
pp. 9473-9486 ◽  
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.

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

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.

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

2010 ◽  
Vol 10 (4) ◽  
pp. 9647-9694 ◽  
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 ◽  
Chemical Effects ◽  
Ozone Depleting Substances ◽  
Year 2000

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.

scholarly journals Future trends in stratosphere-to-troposphere transport in CCMI models

2020 ◽  
Vol 20 (11) ◽  
pp. 6883-6901 ◽  
Author(s):  
Marta Abalos ◽  
Clara Orbe ◽  
Douglas E. Kinnison ◽  
David Plummer ◽  
Luke D. Oman ◽  
...  
Keyword(s):  
21St Century ◽  
Lower Stratosphere ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Hadley Cell ◽  
Tropospheric Chemistry ◽  
Change Scenario ◽  
High Latitudes ◽  
Two Factors ◽  
Ozone Depleting Substances

Abstract. One of the key questions in the air quality and climate sciences is how tropospheric ozone concentrations will change in the future. This will depend on two factors: changes in stratosphere-to-troposphere transport (STT) and changes in tropospheric chemistry. Here we aim to identify robust changes in STT using simulations from the Chemistry Climate Model Initiative (CCMI) under a common climate change scenario (RCP6.0). We use two idealized stratospheric tracers to isolate changes in transport: stratospheric ozone (O3S), which is exactly like ozone but has no chemical sources in the troposphere, and st80, a passive tracer with fixed volume mixing ratio in the stratosphere. We find a robust increase in the tropospheric columns of these two tracers across the models. In particular, stratospheric ozone in the troposphere is projected to increase 10 %–16 % by the end of the 21st century in the RCP6.0 scenario. Future STT is enhanced in the subtropics due to the strengthening of the shallow branch of the Brewer–Dobson circulation (BDC) in the lower stratosphere and of the upper part of the Hadley cell in the upper troposphere. The acceleration of the deep branch of the BDC in the Northern Hemisphere (NH) and changes in eddy transport contribute to increased STT at high latitudes. These STT trends are caused by greenhouse gas (GHG) increases, while phasing out of ozone-depleting substances (ODS) does not lead to robust transport changes. Nevertheless, the decline of ODS increases the reservoir of ozone in the lower stratosphere, which results in enhanced STT of O3S at middle and high latitudes. A higher emission scenario (RCP8.5) produces stronger STT trends, with increases in tropospheric column O3S more than 3 times larger than those in the RCP6.0 scenario by the end of the 21st century.

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

2010 ◽  
Vol 10 (18) ◽  
pp. 8803-8820 ◽  
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.

scholarly journals Future trends in stratosphere-to-troposphere transport in CCMI models

2019 ◽  
Author(s):  
Marta Abalos ◽  
Clara Orbe ◽  
Douglas E. Kinnison ◽  
David Plummer ◽  
Luke D. Oman ◽  
...  
Keyword(s):  
21St Century ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Hadley Cell ◽  
Tropospheric Chemistry ◽  
Change Scenario ◽  
High Latitudes ◽  
Two Factors ◽  
Eddy Transport ◽  
Ozone Depleting Substances

Abstract. One of the key questions in the air quality and climate sciences is how will tropospheric ozone concentrations change in the future. This will depend on two factors: changes in stratosphere-to-troposphere transport (STT) and changes in tropospheric chemistry. Here we aim to identify robust changes in STT using simulations from the Chemistry Climate Model Initiative (CCMI) under a common climate change scenario (RCP6.0). We use two idealized stratospheric tracers to isolate changes in transport: stratospheric ozone (O3S), which is exactly like ozone but has no chemical sources in the troposphere, and st80, a passive tracer with fixed volume mixing ratio in the stratosphere. We find a robust increase in the tropospheric columns of these two tracers across the models. In particular, stratospheric ozone in the troposphere is projected to increase 10–16 % by the end of the 21st century in the RCP6.0 scenario. Future STT is enhanced in the subtropics due to the strengthening of the shallow branch of the Brewer-Dobson circulation (BDC) in the lower stratosphere and of the upper part of the Hadley cell in the upper troposphere. The acceleration of the deep branch of the BDC and changes in eddy transport contribute to increase STT at high latitudes. The idealized tracer st80 shows that these STT changes are dominated by greenhouse gas (GHG) increases, while phasing out of ozone depleting substances (ODS) does not lead to robust STT changes. Nevertheless, the increase of O3S concentrations in the troposphere is attributed to GHG only in the subtropics. At middle and high latitudes it is due to stratospheric ozone recovery linked to ODS decline. A higher emission scenario (RCP8.5) produces qualitatively similar but stronger STT trends, with changes in tropospheric column O3S more than three times larger than those in the RCP6.0 scenario by the end of the 21st century.

scholarly journals Influence of Arctic Stratospheric Ozone on Surface Climate in CCMI models

2018 ◽  
Author(s):  
Ohad Harari ◽  
Chaim I. Garfinkel ◽  
Olaf Morgenstern ◽  
Guang Zeng ◽  
Simone Tilmes ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Climate Model ◽  
Southern Oscillation ◽  
Stratospheric Ozone ◽  
Internal Variability ◽  
Tropical Circulation ◽  
Polar Cap ◽  
Sea Level Pressure ◽  
Surface Climate ◽  
Stratospheric Variability

Abstract. The Northern Hemisphere and tropical circulation response to interannual variability in Arctic stratospheric ozone is analyzed in a set of the latest model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project. All models simulate a connection between ozone variability and temperature/geopotential height in the lower stratosphere similar to that observed. A connection between Arctic ozone variability and polar cap sea-level pressure is also found, but additional analysis suggests that it is mediated by the dynamical variability that typically drives the anomalous ozone concentrations. The CCMI models also show a connection between Arctic stratospheric ozone and the El Nino Southern Oscillation (ENSO): the CCMI models show a tendency of Arctic stratospheric ozone variability to lead ENSO variability one to two years later. While this effect is much weaker than that observed, it is still statistically significant. Overall, Arctic stratospheric ozone is related to lower stratospheric variability and may also influence the surface in both polar and tropical latitudes, though these impacts can be masked by internal variability if data is only available for ~ 40 years.

scholarly journals Chemical and climatic drivers of radiative forcing due to changes in stratospheric and tropospheric ozone over the 21<sup>st</sup> century

2017 ◽  
Author(s):  
Antara Banerjee ◽  
Amanda C. Maycock ◽  
John A. Pyle
Keyword(s):  
Greenhouse Gas ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Radiative Forcings ◽  
Climatic Drivers ◽  
Ozone Precursor ◽  
Ozone Depleting Substances ◽  
Projected Changes

Abstract. The ozone radiative forcings (RFs) resulting from projected changes in climate, ozone-depleting substances (ODSs), non-methane ozone precursor emissions and methane between the years 2000 and 2100 are calculated using simulations from the UM-UKCA chemistry-climate model. Projected measures to improve air-quality through reductions in tropospheric ozone precursor emissions present a co-benefit for climate, with a net global mean ozone RF of −0.09 Wm−2. This is opposed by a positive ozone RF of 0.07 Wm−2 due to future decreases in ODSs, which is mainly driven by an increase in tropospheric ozone through stratosphere-to-troposphere exchange. An increase in methane abundance by more than a factor of two (as projected by the RCP8.5 scenario) is found to drive an ozone RF of 0.19 Wm−2, which would greatly outweigh the climate benefits of tropospheric non-methane ozone precursor reductions. A third of the ozone RF due to the projected increase in methane results from increases in stratospheric ozone. The sign of the ozone RF due to future changes in climate (including the radiative effects of greenhouse gas concentrations, sea surface temperatures and sea ice changes) is shown to be dependent on the greenhouse gas emissions pathway, with a positive RF (0.06 Wm−2) for RCP4.5 and a negative RF (−0.07 Wm−2) for the RCP8.5 scenario. This dependence arises from differences in the contribution to RF from stratospheric ozone changes.

scholarly journals Stratospheric ozone in the post-CFC era

2008 ◽  
Vol 8 (6) ◽  
pp. 20223-20237 ◽  
Author(s):  
F. Li ◽  
R. S. Stolarski ◽  
P. A. Newman
Keyword(s):  
Greenhouse Gas ◽  
21St Century ◽  
Crucial Role ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Advective Transport ◽  
Recent Past ◽  
Column Ozone ◽  
The Tropics

Abstract. Vertical and latitudinal changes in the stratospheric ozone in the post-chlorofluorocarbon (CFC) era are investigated using simulations of the recent past and the 21st century with a coupled chemistry-climate model. Model results reveal that, in the 2060s when the stratospheric halogen loading is projected to return to its 1980 values, the extratropical column ozone is significantly higher than that in 1975–1984, but the tropical column ozone does not recover to 1980 values. Upper and lower stratospheric ozone changes in the post-CFC era have very different patterns. Above 15 hPa ozone increases almost latitudinally uniformly by 6 Dobson Unit (DU), whereas below 15 hPa ozone decreases in the tropics by 8 DU and increases in the extratropics by up to 16 DU. The upper stratospheric ozone increase is a photochemical response to greenhouse gas induced strong cooling, and the lower stratospheric ozone changes are consistent with enhanced mean advective transport due to a stronger Brewer-Dobson circulation. The model results suggest that the strengthening of the Brewer-Dobson circulation plays a crucial role in ozone recovery and ozone distributions in the post-CFC era.

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

2018 ◽  
Vol 18 (9) ◽  
pp. 6121-6139 ◽  
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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