scholarly journals Options to accelerate ozone recovery: ozone and climate benefits

2010 ◽  
Vol 10 (16) ◽  
pp. 7697-7707 ◽  
Author(s):  
J. S. Daniel ◽  
E. L. Fleming ◽  
R. W. Portmann ◽  
G. J. M. Velders ◽  
C. H. Jackman ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Radiative Forcing ◽  
Montreal Protocol ◽  
N2o Emissions ◽  
Total Column Ozone ◽  
Potential Impact ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
The Impact ◽  
Total Column

Abstract. Hypothetical reductions in future emissions of ozone-depleting substances (ODSs) and N2O are evaluated in terms of effects on equivalent effective stratospheric chlorine (EESC), globally-averaged total column ozone, and radiative forcing through 2100. Due to the established success of the Montreal Protocol, these actions can have only a fraction of the impact on ozone depletion that regulations already in force have had. If all anthropogenic ODS and N2O emissions were halted beginning in 2011, ozone is calculated to be higher by about 1–2% during the period 2030–2100 compared to a case of no additional restrictions. Direct radiative forcing by 2100 would be about 0.23 W/m2 lower from the elimination of anthropogenic N2O emissions and about 0.005 W/m2 lower from the destruction of the chlorofluorocarbon (CFC) bank. Due to the potential impact of N2O on future ozone levels, we provide an approach to incorporate it into the EESC formulation, which is used extensively in ozone depletion analyses. The ability of EESC to describe total ozone changes arising from additional ODS and N2O controls is also quantified.

scholarly journals Options to accelerate ozone recovery:ozone and climate benefits

2010 ◽  
Vol 10 (4) ◽  
pp. 10839-10863
Author(s):  
J. S. Daniel ◽  
E. L. Fleming ◽  
R. W. Portmann ◽  
G. J. M. Velders ◽  
C. H. Jackman ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Total Ozone ◽  
Montreal Protocol ◽  
N2o Emissions ◽  
Total Column Ozone ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
The Impact ◽  
Total Column ◽  
Future Emissions

Abstract. Hypothetical reductions in future emissions of ozone-depleting substances (ODSs), including N2O, are evaluated in terms of effects on equivalent effective stratospheric chlorine (EESC), globally-averaged total column ozone, and radiative forcing through 2100. Due to the established success of the Montreal Protocol, these actions can have only a fraction of the impact that regulations already in force have had. If all anthropogenic ODS emissions were halted beginning in 2011, ozone is calculated to be higher by about 1–2{%} during the period 2030–2100 compared to a case of no additional ODS restrictions. Radiative forcing by 2100 would be about 0.23 W/m2 lower due to the elimination of N2O emissions and about 0.005 W/m2 lower due to destruction of the chlorofluorocarbon (CFC) bank. The ability of EESC to be a suitable metric for total ozone is also quantified. Responding to the recent suggestion that N2O should be considered an ODS, we provide an approach to incorporate N2O into the EESC formulation.

scholarly journals Antarctic ozone depletion between 1960 and 1980 in observations and chemistry–climate model simulations

2016 ◽  
Vol 16 (24) ◽  
pp. 15619-15627 ◽  
Author(s):  
Ulrike Langematz ◽  
Franziska Schmidt ◽  
Markus Kunze ◽  
Gregory E. Bodeker ◽  
Peter Braesicke
Keyword(s):  
Ozone Depletion ◽  
Climate Model ◽  
Total Column Ozone ◽  
Antarctic Ozone ◽  
Climate Model Simulations ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
The Antarctic ◽  
Total Column

Abstract. The year 1980 has often been used as a benchmark for the return of Antarctic ozone to conditions assumed to be unaffected by emissions of ozone-depleting substances (ODSs), implying that anthropogenic ozone depletion in Antarctica started around 1980. Here, the extent of anthropogenically driven Antarctic ozone depletion prior to 1980 is examined using output from transient chemistry–climate model (CCM) simulations from 1960 to 2000 with prescribed changes of ozone-depleting substance concentrations in conjunction with observations. A regression model is used to attribute CCM modelled and observed changes in Antarctic total column ozone to halogen-driven chemistry prior to 1980. Wintertime Antarctic ozone is strongly affected by dynamical processes that vary in amplitude from year to year and from model to model. However, when the dynamical and chemical impacts on ozone are separated, all models consistently show a long-term, halogen-induced negative trend in Antarctic ozone from 1960 to 1980. The anthropogenically driven ozone loss from 1960 to 1980 ranges between 26.4 ± 3.4 and 49.8 ± 6.2 % of the total anthropogenic ozone depletion from 1960 to 2000. An even stronger ozone decline of 56.4 ± 6.8 % was estimated from ozone observations. This analysis of the observations and simulations from 17 CCMs clarifies that while the return of Antarctic ozone to 1980 values remains a valid milestone, achieving that milestone is not indicative of full recovery of the Antarctic ozone layer from the effects of ODSs.

scholarly journals Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery

2018 ◽  
Vol 18 (2) ◽  
pp. 1379-1394 ◽  
Author(s):  
William T. Ball ◽  
Justin Alsing ◽  
Daniel J. Mortlock ◽  
Johannes Staehelin ◽  
Joanna D. Haigh ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Montreal Protocol ◽  
Downward Trend ◽  
Polar Regions ◽  
Total Column Ozone ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
Total Column

Abstract. Ozone forms in the Earth's atmosphere from the photodissociation of molecular oxygen, primarily in the tropical stratosphere. It is then transported to the extratropics by the Brewer–Dobson circulation (BDC), forming a protective ozone layer around the globe. Human emissions of halogen-containing ozone-depleting substances (hODSs) led to a decline in stratospheric ozone until they were banned by the Montreal Protocol, and since 1998 ozone in the upper stratosphere is rising again, likely the recovery from halogen-induced losses. Total column measurements of ozone between the Earth's surface and the top of the atmosphere indicate that the ozone layer has stopped declining across the globe, but no clear increase has been observed at latitudes between 60° S and 60° N outside the polar regions (60–90°). Here we report evidence from multiple satellite measurements that ozone in the lower stratosphere between 60° S and 60° N has indeed continued to decline since 1998. We find that, even though upper stratospheric ozone is recovering, the continuing downward trend in the lower stratosphere prevails, resulting in a downward trend in stratospheric column ozone between 60° S and 60° N. We find that total column ozone between 60° S and 60° N appears not to have decreased only because of increases in tropospheric column ozone that compensate for the stratospheric decreases. The reasons for the continued reduction of lower stratospheric ozone are not clear; models do not reproduce these trends, and thus the causes now urgently need to be established.

scholarly journals Diagnosing the radiative and chemical contributions to future changes in tropical column ozone with the UM-UKCA chemistry-climate model

2017 ◽  
Author(s):  
James Keeble ◽  
Ewa M. Bednarz ◽  
Antara Banerjee ◽  
N. Luke Abraham ◽  
Neil R. P. Harris ◽  
...  
Keyword(s):  
21St Century ◽  
Climate Model ◽  
Montreal Protocol ◽  
Total Column Ozone ◽  
Future Evolution ◽  
The Future ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
Total Column ◽  
Emissions Scenario

Abstract. Chemical and dynamical drivers of trends in tropical total column ozone (TCO3) for the recent past and future periods are explored using the UM-UKCA chemistry-climate model. A transient 1960-2100 simulation is analysed which follows the representative concentration pathway 6.0 (RCP6.0) emissions scenario for the future. Tropical averaged (10° S–10° N) TCO3 values decrease from the 1970s, reaching a minimum around 2000, and return to their 1980 values around 2040, consistent with the use and emission of ozone depleting substances (ODS), and their later controls under the Montreal Protocol. However, when the ozone column is subdivided into three partial columns (PCO3) that cover the upper stratosphere (PCO3US), lower stratosphere (PCO3LS) and troposphere (PCO3T), significant differences to the behaviour of the total column are seen. Modelled PCO3T values increase from 1960–2000 before remaining steady under this particular emissions scenario throughout the 21st century. PCO3LS values decrease rapidly from 1960–2000, remain steady until around 2050, before gradually decreasing further to 2100, never recovering to their 1980s values. PCO3US values decrease from 1960–2000, before rapidly increasing throughout the 21st century, recovering to 1980s values by ~ 2020, and are significantly higher than 1980s values by 2100. Using a series of idealised UM-UKCA time-slice simulations with varying concentrations of well-mixed greenhouse gases (GHG) and ODS set to either year 2000 or 2100 levels, we examine the main processes that drive the PCO3 responses in the three regions, and assess how these processes change under different emission scenarios. Finally, we present a simple, linearised model to describe the future evolution of tropical stratospheric column ozone values based on terms representing time-dependent abundances of GHG and ODS.

scholarly journals Reevaluation of total-column ozone trends and of the Effective Radiative Forcing of ozone-depleting substances

2021 ◽  
Author(s):  
Olaf Morgenstern ◽  
Stacey M Frith ◽  
Gregory Elton Bodeker ◽  
Vitali Fioletov ◽  
Dr. Ronald Vander A
Keyword(s):  
Radiative Forcing ◽  
Total Column Ozone ◽  
Ozone Trends ◽  
Effective Radiative Forcing ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
Total Column

scholarly journals Modelling the potential impacts of the recent, unexpected increase in CFC-11 emissions on total column ozone recovery

2019 ◽  
Author(s):  
James Keeble ◽  
N. Luke Abraham ◽  
Alexander T. Archibald ◽  
Martyn P. Chipperfield ◽  
Sandip Dhomse ◽  
...  
Keyword(s):  
Montreal Protocol ◽  
Significant Delay ◽  
Total Column Ozone ◽  
Rapid Action ◽  
Emissions Scenarios ◽  
Column Ozone ◽  
The Impact ◽  
Long Term Measurement ◽  
Total Column

Abstract. The temporal evolution of long-lived, anthropogenic chlorofluorocarbons is a key control on the timing of total column ozone (TCO) recovery. Recent observations have shown that the atmospheric mixing ratio of CFC-11 is not declining as expected under complete compliance with the Montreal Protocol, and indicate a new source of CFC-11. In this study, the impact of a number of potential future CFC-11 emissions scenarios on TCO recovery is investigated using the UM-UKCA model. Key uncertainties related to this new CFC-11 source and their impact on the timing of TCO recovery are explored, including: the duration of new CFC-11 emissions/production; the impact of any newly created bank; and the effects of co-production of CFC-12. Scenario-independent relationships are identified between cumulative CFC emissions and the timing of ozone recovery, which can be used to establish the impact of future CFC emissions pathways on ozone recovery in the real world. It is found that, for every 200 Gg Cl emitted, the timing of global TCO recovery is delayed by ~ 0.56 years. However, a marked hemispheric asymmetry in the latitudinal impacts of cumulative Cl emissions on the timing of TCO recovery is identified, with longer delays in the southern hemisphere than the northern hemisphere for the same emission. Together, these results indicate that, if rapid action is taken to curb recently identified CFC-11 production then no significant delay in the timing of TCO recovery is expected, highlighting the importance of ongoing, long-term measurement efforts to inform the accountability phase of the Montreal Protocol. However, if the emissions are allowed to continue into the future, and are associated with the creation of large banks, then significant delays in the timing of TCO recovery may occur.

scholarly journals Modelling the potential impacts of the recent, unexpected increase in CFC-11 emissions on total column ozone recovery

2020 ◽  
Vol 20 (12) ◽  
pp. 7153-7166
Author(s):  
James Keeble ◽  
N. Luke Abraham ◽  
Alexander T. Archibald ◽  
Martyn P. Chipperfield ◽  
Sandip Dhomse ◽  
...  
Keyword(s):  
Montreal Protocol ◽  
Total Column Ozone ◽  
The Road ◽  
The United Kingdom ◽  
Full Compliance ◽  
Rapid Action ◽  
On The Road ◽  
Column Ozone ◽  
The Impact ◽  
Total Column

Abstract. The temporal evolution of the abundance of long-lived, anthropogenic chlorofluorocarbons in the atmosphere is a major factor in determining the timing of total column ozone (TCO) recovery. Recent observations have shown that the atmospheric mixing ratio of CFC-11 is not declining as rapidly as expected under full compliance with the Montreal Protocol and indicate a new source of CFC-11 emissions. In this study, the impact of a number of potential future CFC-11 emissions scenarios on the timing of the TCO return to the 1960–1980 mean (an important milestone on the road to recovery) is investigated using the Met Office's Unified Model (Hewitt et al., 2011) coupled with the United Kingdom Chemistry and Aerosol scheme (UM-UKCA). Key uncertainties related to this new CFC-11 source and their impact on the timing of the TCO return date are explored, including the duration of new CFC-11 production and emissions; the impact of any newly created CFC-11 bank; and the effects of co-production of CFC-12. Scenario-independent relationships are identified between cumulative CFC emissions and the timing of the TCO return date, which can be used to establish the impact of future CFC emissions pathways on ozone recovery in the real world. It is found that, for every 200 Gg Cl (∼258 Gg CFC-11) emitted, the timing of the global TCO return to 1960–1980 averaged values is delayed by ∼0.56 years. However, a marked hemispheric asymmetry in the latitudinal impacts of cumulative Cl emissions on the timing of the TCO return date is identified, with longer delays in the Southern Hemisphere than the Northern Hemisphere for the same emission. Together, these results indicate that, if rapid action is taken to curb recently identified CFC-11 production, then no significant delay in the timing of the TCO return to the 1960–1980 mean is expected, highlighting the importance of ongoing, long-term measurement efforts to inform the accountability phase of the Montreal Protocol. However, if the emissions are allowed to continue into the future and are associated with the creation of large banks, then significant delays in the timing of the TCO return date may occur.

scholarly journals Ozone sensitivity to varying greenhouse gases and ozone-depleting substances in CCMI simulations

2017 ◽  
Author(s):  
Olaf Morgenstern ◽  
Hideharu Akiyoshi ◽  
Yousuke Yamashita ◽  
Douglas E. Kinnison ◽  
Rolando R. Garcia ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Climate Model ◽  
Phase 1 ◽  
Coupled Model ◽  
Total Column Ozone ◽  
Ozone Sensitivity ◽  
Intercomparison Project ◽  
Ozone Depleting Substances ◽  
Column Ozone ◽  
Total Column

Abstract. Ozone fields simulated for the Chemistry-Climate Model Initiative (CCMI) will be used as forcing data in the 6th Coupled Model Intercomparison Project (CMIP6). Here we assess, using reference and sensitivity simulations produced for phase 1 of CCMI, the suitability of CCMI-1 model results for this process, investigating the degree of consistency amongst models regarding their responses to variations in individual forcings. We consider the influences of methane, nitrous oxide, a combination of chlorinated or brominated ozone-depleting substances (ODSs), and a combination of carbon dioxide and other greenhouse gases (GHGs). We find varying degrees of consistency in the models' responses in ozone to these individual forcings, including some considerable disagreement. In particular, the response of total-column ozone to these forcings is less consistent across the multi-model ensemble than profile comparisons. The likely cause of this is lower-stratospheric transport and dynamical responses exhibiting substantial inter-model differences. The findings imply that the ozone fields derived from CCMI-1 are subject to considerable uncertainties regarding the impacts of these anthropogenic forcings.

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