New Insights on the Impact of Ozone‐Depleting Substances on the Brewer‐Dobson Circulation

Abstract. High frequency, in situ global observations of HCFC-22 (CHClF2), HCFC-141b (CH3CCl2F), HCFC-142b (CH3CClF2) and HCFC-124 (CHClFCF3) and their main HFC replacements HFC-134a (CH2FCF3), HFC-125 (CHF2CF3), HFC-143a (CH3CF3), and HFC-32 (CH2F2) have been used to determine their changing global growth rates and emissions in response to the Montreal Protocol and its recent amendments. The 2007 adjustment to the Montreal Protocol required the accelerated phase-out of HCFCs with global production and consumption capped in 2013, to mitigate their environmental impact as both ozone depleting substances and important greenhouse gases. We find that this change has coincided with a reduction in global emissions of the four HCFCs with aggregated global emissions in 2015 of 444 ± 75 Gg/yr, in CO2 equivalent units (CO2 e) 0.75 ± 0.1 Gt/yr, compared with 483 ± 70 Gg/yr (0.82 ± 0.1 Gt/yr CO2 e) in 2010. (All quoted uncertainties in this paper are 1 sigma). About 80 % of the total HCFC atmospheric burden in 2015 is HCFC-22, where global HCFC emissions appear to have been relatively constant in spite of the 2013 cap on global production and consumption. We attribute this to a probable increase in production and consumption of HCFC-22 in Montreal Protocol Article 5 (developing) countries and the continuing release of HCFC-22 from the large banks which dominate HCFC global emissions. Conversely, the four HFCs all show increasing annual growth rates with aggregated global HFCs emissions in 2015 of 329 ± 70 Gg/yr (0.65 ± 0.12 Gt/yr CO2 e) compared to 2010 with 240 ± 50 Gg/yr (0.47 ± 0.08 Gt/yr CO2 e). As HCFCs are replaced by HFCs we investigate the impact of the shift to refrigerant blends which have lower global warming potentials (GWPs). We also note that emissions of HFC-125 and HFC-32 appear to have increased more rapidly during the 2011–2015 5-yr period compared to 2006–2010.

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Atmospheric impacts of short-lived chlorinated species over the recent past: a chemistry-climate perspective

10.5194/egusphere-egu21-12824 ◽

2021 ◽

Author(s):

Ewa Bednarz ◽

Ryan Hossaini ◽

Luke Abraham ◽

Peter Braesicke ◽

Martyn Chipperfield

Keyword(s):

Atmospheric Chemistry ◽

Climate Model ◽

Stratospheric Ozone ◽

Lower Boundary ◽

Montreal Protocol ◽

Recent Past ◽

Substantial Impact ◽

Ozone Depleting Substances ◽

The Impact

The emissions of most long-lived halogenated ozone-depleting substances (ODSs) are now decreasing, owing to controls on their production introduced by Montreal Protocol and its amendments. However, short-lived halogenated compounds can also have substantial impact on atmospheric chemistry, including stratospheric ozone, particularly if emitted near climatological uplift regions. It has recently become evident that emissions of some chlorinated very short-lived species (VSLSs), such as chloroform (CHCl3) and dichloromethane (CH2Cl2), could be larger than previously believed and increasing, particularly in Asia. While these may exert a significant influence on atmospheric chemistry and climate, their impacts remain poorly characterised.&#160;&#160;We address this issue using the UM-UKCA chemistry-climate model (CCM). While not only the first, to our knowledge, model study addressing this problem using a CCM, it is also the first such study employing a whole atmosphere model, thereby simulating the tropospheric Cl-VSLSs emissions and the resulting stratospheric impacts in a fully consistent manner. We use a newly developed Double-Extended Stratospheric-Tropospheric (DEST) chemistry scheme, which includes emissions of all major chlorinated and brominated VSLSs alongside an extended treatment of long-lived ODSs.&#160;We examine the impacts of rising Cl-VSLSs emissions on atmospheric chlorine tracers and ozone, including their long-term trends. We pay particular attention to the role of &#8216;nudging&#8217;, as opposed to the free-running model set up, for the simulated Cl-VSLSs impacts, thereby demostrating the role of atmospheric dynamics in modulating the atmospheric responses to Cl-VSLSs. In addition, we employ novel estimates of Cl-VSLS emissions over the recent past and compare the results with the simulations that prescribe Cl-VSLSs using simple lower boundary conditions. This allows us to demonstrate the impact such choice has on the dominant location and seasonality of the Cl-VSLSs transport into the stratosphere.

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The impact of ozone depleting substances on the circulation, temperature, and salinity of the Southern Ocean: An attribution study with CESM1(WACCM)

Geophysical Research Letters ◽

10.1002/2015gl064744 ◽

2015 ◽

Vol 42 (13) ◽

pp. 5547-5555 ◽

Cited By ~ 23

Author(s):

A. Solomon ◽

L. M. Polvani ◽

K. L. Smith ◽

R. P. Abernathey

Keyword(s):

Southern Ocean ◽

Ozone Depleting Substances ◽

The Impact

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The Impact of Ozone-Depleting Substances on Tropical Upwelling, as Revealed by the Absence of Lower-Stratospheric Cooling since the Late 1990s

Journal of Climate ◽

10.1175/jcli-d-16-0532.1 ◽

2017 ◽

Vol 30 (7) ◽

pp. 2523-2534 ◽

Cited By ~ 23

Author(s):

Lorenzo M. Polvani ◽

Lei Wang ◽

Valentina Aquila ◽

Darryn W. Waugh

Keyword(s):

Greenhouse Gases ◽

Lower Stratosphere ◽

Stratospheric Temperature ◽

Temperature Trends ◽

Ozone Trends ◽

Primary Driver ◽

Stratospheric Cooling ◽

Ozone Depleting Substances ◽

The Tropics ◽

The Impact

The impact of ozone-depleting substances on global lower-stratospheric temperature trends is widely recognized. In the tropics, however, understanding lower-stratospheric temperature trends has proven more challenging. While the tropical lower-stratospheric cooling observed from 1979 to 1997 has been linked to tropical ozone decreases, those ozone trends cannot be of chemical origin, as active chlorine is not abundant in the tropical lower stratosphere. The 1979–97 tropical ozone trends are believed to originate from enhanced upwelling, which, it is often stated, would be driven by increasing concentrations of well-mixed greenhouse gases. This study, using simple arguments based on observational evidence after 1997, combined with model integrations with incrementally added single forcings, argues that trends in ozone-depleting substances, not well-mixed greenhouse gases, have been the primary driver of temperature and ozone trends in the tropical lower stratosphere until 1997, and this has occurred because ozone-depleting substances are key drivers of tropical upwelling and, more generally, of the entire Brewer–Dobson circulation.

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Options to accelerate ozone recovery: ozone and climate benefits

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-7697-2010 ◽

2010 ◽

Vol 10 (16) ◽

pp. 7697-7707 ◽

Cited By ~ 15

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.

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Life Cycle Assessment of Methyl Bromide Production and Utilization: Cradle to Grave Analysis

10.21203/rs.3.rs-605031/v1 ◽

2021 ◽

Author(s):

Sampatrao Manjare ◽

Amit Shanbag

Keyword(s):

Life Cycle Assessment ◽

Life Cycle ◽

Methyl Bromide ◽

Substantial Effect ◽

Environmental Damage ◽

Methanol Production ◽

Health Related ◽

Cradle To Gate ◽

Ozone Depleting Substances ◽

The Impact

Abstract Methyl bromide is an effective and useful insecticide. It has ability to enter rapidly into materials at room temperature & pressure. Nowadays, it is primarily used for container fumigation purposes. However, exposure to it causes serious health-related issues. It is also one of the ozone-depleting substances. In this work, “cradle to gate” and “cradle to grave” approaches are considered to carry out a life cycle assessment of methyl bromide production. SimaPro software with the IMPACT 2002+ method is used to compute the results. From the results of cradle to gate approach, it is inferred that major emissions are due to usage of plant utilities and methanol production process which have a substantial effect on the atmosphere. From the results of cradle to grave approach, it is noted that application of methyl bromide causes significant environmental damage particularly to ozone layer followed by non-carcinogen.

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Improved characterisation of the impact of chlorinated VSLSs on atmospheric chemistry and climate: past, present and future

10.5194/egusphere-egu2020-10611 ◽

2020 ◽

Author(s):

Ewa Bednarz ◽

Ryan Hossaini ◽

Luke Abraham ◽

Martyn Chipperfield

Keyword(s):

Atmospheric Chemistry ◽

Climate Model ◽

Stratospheric Ozone ◽

Montreal Protocol ◽

Recent Past ◽

Substantial Impact ◽

Emissions Scenarios ◽

Ozone Depleting Substances ◽

The Impact ◽

Future Emissions

The emissions of most long-lived halogenated ozone-depleting substances (ODSs) are now decreasing, owing to controls on their production introduced by Montreal Protocol and its amendments. However, short-lived halogenated compounds can also have substantial impact on atmospheric chemistry, including stratospheric ozone, particularly if emitted near climatological uplift regions. It has recently become evident that emissions of some chlorinated very short-lived species (VSLSs), such as chloroform (CHCl3) and dichloromethane (CH2Cl2), could be larger than previously believed and increasing, particularly in Asia. While these may exert a significant influence on atmospheric chemistry and climate, their impacts remain poorly characterised.&#160;We address this issue using the UM-UKCA chemistry-climate model. We use a newly developed Double-Extended Stratospheric-Tropospheric (DEST) chemistry scheme, which includes emissions of all major chlorinated and brominated VSLSs alongside an extended treatment of long-lived ODSs. Employing novel estimates of Cl-VSLS emissions we show model results regarding the atmospheric impacts of chlorinated VSLSs over the recent past (2000-present), with a focus on stratospheric ozone and HCl trends. Finally, we introduce our plans regarding examining the impacts of chlorinated VSLSs under a range of potential future emissions scenarios; the results of which will be directly relevant for the next WMO/UNEP assessment.

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Update and evaluation of the ozone dry deposition in the Oslo CTM3 v1.0

10.5194/gmd-2019-21 ◽

2019 ◽

Author(s):

Stefanie Falk ◽

Amund Søvde Haslerud

Keyword(s):

Dry Deposition ◽

Surface Ozone ◽

High Sensitivity ◽

Ambient Air ◽

Limiting Factors ◽

Model Studies ◽

Ozone Concentrations ◽

The Future ◽

Ozone Depleting Substances ◽

The Impact

Abstract. High concentrations of ozone in ambient air are hazardous not only to humans but to the ecosystem in general. The impact of ozone damage on vegetation and agricultural plants in combination with advancing climate change may affect food security in the future. While the future scenarios in themselves are uncertain, there are limiting factors constraining the accuracy of surface ozone modeling also at present: The distribution and amount of ozone precursors and ozone depleting substances, the stratosphere-troposphere exchange as well as scavenging processes. Removal of any substance through gravitational settling or by uptake by plants and soil is referred to as dry deposition. The process of dry deposition is important for predicting surface ozone concentrations and understanding the observed amount and increase of tropospheric background ozone. The conceptual dry deposition velocities are calculated following a resistance-analogous approach wherein aerodynamic, quasi laminar, and canopy resistances are key components, but these are hard to measure explicitly. In this paper, we present an update of the dry deposition scheme implemented in the Oslo CTM3. We change from a purely empirical dry deposition parameterization to a more process-based one which is taking the state of the atmosphere and vegetation into account. Examining the sensitivity of the scheme to various parameters, our focus lies mainly on the stomatal conductance-based description of the canopy resistance. We evaluate the resulting modeled ozone dry deposition with respect to observations and multi-model studies and also estimate the impact on the modeled ozone concentrations at the surface. We show that the global annual total ozone dry deposition decreases with respect to the previous model version (−47 %), leading to an increase in surface ozone of up to 100 %. While high sensitivity to changes in dry deposition to vegetation is found in the tropics, the largest impact on global scales is associated to changes in dry deposition to the ocean and deserts.

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Consumers and Intermediate Producers in the Phase-out of Agricultural and Industrial Ozone-Depleting Substances

10.1093/oso/9780190677725.003.0003 ◽

2017 ◽

Author(s):

Alexander Ovodenko

Keyword(s):

Methyl Bromide ◽

Consumer Preferences ◽

Market Competition ◽

Montreal Protocol ◽

Environmental Regime ◽

Consumer Markets ◽

Confounding Variables ◽

Ozone Depleting Substances ◽

Phase Out ◽

The Impact

The chapter analyzes the impact of downstream consumer markets on environmental regime design by explaining why wealthy countries have successfully phased out industrial ozone-depleting substances (ODS) but not an agricultural pesticide known as methyl bromide under the Montreal Protocol, despite the 2005 phase-out deadline for that pesticide. Since the analysis focuses on the regulation of different sectors under the same treaty, it isolates the impact of markets without the threat of major confounding variables interfering with the conclusions. It emphasizes competitive pressures and the structure of intermediate producers in the industrial and agricultural markets employing ODS to explain why methyl bromide has been handled differently from industrial refrigerants. The findings illustrate the impacts of consumer preferences and market competition on the investments of fluoro-product companies and, in turn, on the policies of wealthy countries and rules in the ozone regime.

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The Importance of the Montreal Protocol in Mitigating the Potential Intensity of Tropical Cyclones

Journal of Climate ◽

10.1175/jcli-d-15-0232.1 ◽

2016 ◽

Vol 29 (6) ◽

pp. 2275-2289 ◽

Cited By ~ 10

Author(s):

Lorenzo M. Polvani ◽

Suzana J. Camargo ◽

Rolando R. Garcia

Keyword(s):

Tropical Cyclones ◽

Climate Model ◽

Atmospheric Model ◽

Montreal Protocol ◽

Discernible Effect ◽

Major Player ◽

The World ◽

Standard Scenario ◽

Ozone Depleting Substances ◽

The Impact

Abstract The impact of the Montreal Protocol on the potential intensity of tropical cyclones over the next 50 years is investigated with the Whole Atmosphere Community Climate Model (WACCM), a state-of-the-art, stratosphere-resolving atmospheric model, coupled to land, ocean, and sea ice components, with interactive stratospheric chemistry. An ensemble of WACCM runs from 2006 to 2065 forced with a standard future scenario is compared to a second ensemble in which ozone-depleting substances (ODS) are not regulated (the so-called World Avoided). It is found that by the year 2065, changes in the potential intensity of tropical cyclones in the World Avoided are nearly 3 times as large as for the standard scenario. The Montreal Protocol thus provides a strong mitigation of the adverse effects of intensifying tropical cyclones. The relative importance of warmer sea surface temperatures (ozone-depleting substances are important greenhouse gases) and cooler lower-stratospheric temperatures (accompanying the massive destruction of the ozone layer) is carefully examined. It is found that the former are largely responsible for the increase in potential intensity in the World Avoided, whereas temperatures above the 70-hPa level—which plunge by nearly 15 K in 2065 in the World Avoided—have no discernible effect on potential intensity. This finding suggests that the modest (compared to the World Avoided) tropical ozone depletion of recent decades has not been a major player in determining the intensity of tropical cyclones, and neither will ozone recovery be in the coming half century.

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