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

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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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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Simulations of preindustrial, present-day, and 2100 conditions in the NASA GISS composition and climate model G-PUCCINI

Atmospheric Chemistry and Physics ◽

10.5194/acp-6-4427-2006 ◽

2006 ◽

Vol 6 (12) ◽

pp. 4427-4459 ◽

Cited By ~ 123

Author(s):

D. T. Shindell ◽

G. Faluvegi ◽

N. Unger ◽

E. Aguilar ◽

G. A. Schmidt ◽

...

Keyword(s):

Climate Change ◽

Tropospheric Ozone ◽

Radiative Forcing ◽

Climate Model ◽

Stratospheric Ozone ◽

Atmospheric Composition ◽

Downward Flux ◽

Magnitude Distribution ◽

Goddard Institute ◽

Global Mean

Abstract. A model of atmospheric composition and climate has been developed at the NASA Goddard Institute for Space Studies (GISS) that includes composition seamlessly from the surface to the lower mesosphere. The model is able to capture many features of the observed magnitude, distribution, and seasonal cycle of trace species. The simulation is especially realistic in the troposphere. In the stratosphere, high latitude regions show substantial biases during period when transport governs the distribution as meridional mixing is too rapid in this model version. In other regions, including the extrapolar tropopause region that dominates radiative forcing (RF) by ozone, stratospheric gases are generally well-simulated. The model's stratosphere-troposphere exchange (STE) agrees well with values inferred from observations for both the global mean flux and the ratio of Northern (NH) to Southern Hemisphere (SH) downward fluxes. Simulations of preindustrial (PI) to present-day (PD) changes show tropospheric ozone burden increases of 11% while the stratospheric burden decreases by 18%. The resulting tropopause RF values are −0.06 W/m2 from stratospheric ozone and 0.40 W/m2 from tropospheric ozone. Global mean mass-weighted OH decreases by 16% from the PI to the PD. STE of ozone also decreased substantially during this time, by 14%. Comparison of the PD with a simulation using 1979 pre-ozone hole conditions for the stratosphere shows a much larger downward flux of ozone into the troposphere in 1979, resulting in a substantially greater tropospheric ozone burden than that seen in the PD run. This implies that reduced STE due to stratospheric ozone depletion may have offset as much as 2/3 of the tropospheric ozone burden increase from PI to PD. However, the model overestimates the downward flux of ozone at high Southern latitudes, so this estimate is likely an upper limit. In the future, the tropospheric ozone burden increases by 101% in 2100 for the A2 scenario including both emissions and climate changes. The primary reason is enhanced STE, which increases by 124% (168% in the SH extratropics, and 114% in the NH extratropics). Climate plays a minimal role in the SH increases, but contributes 38% in the NH. Chemistry and dry deposition both change so as to reduce tropospheric ozone, partially in compensation for the enhanced STE, but the increased ozone influx dominates the burden changes. The net RF due to projected ozone changes is 0.8 W/m2 for A2. The influence of climate change alone is −0.2 W/m2, making it a substantial contributor to the net RF. The tropospheric oxidation capacity increases seven percent in the full A2 simulation, and 36% due to A2 climate change alone.

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

10.5194/acp-2017-741 ◽

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.

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Potential escalation of heat-related working costs with climate and socioeconomic changes in China

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1521828113 ◽

2016 ◽

Vol 113 (17) ◽

pp. 4640-4645 ◽

Cited By ~ 24

Author(s):

Yan Zhao ◽

Benjamin Sultan ◽

Robert Vautard ◽

Pascale Braconnot ◽

Huijun J. Wang ◽

...

Keyword(s):

Climate Change ◽

21St Century ◽

Radiative Forcing ◽

Socioeconomic Development ◽

Climate Model ◽

Global Climate ◽

Mainland China ◽

Labor Cost ◽

Labor Costs ◽

Socioeconomic Changes

Global climate change will increase the frequency of hot temperatures, impairing health and productivity for millions of working people and raising labor costs. In mainland China, high-temperature subsidies (HTSs) are allocated to employees for each working day in extremely hot environments, but the potential heat-related increase in labor cost has not been evaluated so far. Here, we estimate the potential HTS cost in current and future climates under different scenarios of socioeconomic development and radiative forcing (Representative Concentration Pathway), taking uncertainties from the climate model structure and bias correction into account. On average, the total HTS in China is estimated at 38.6 billion yuan/y (US $6.22 billion/y) over the 1979–2005 period, which is equivalent to 0.2% of the gross domestic product (GDP). Assuming that the HTS standards (per employee per hot day) remain unchanged throughout the 21st century, the total HTS may reach 250 billion yuan/y in the 2030s and 1,000 billion yuan/y in 2100. We further show that, without specific adaptation, the increased HTS cost is mainly determined by population growth until the 2030s and climate change after the mid-21st century because of increasingly frequent hot weather. Accounting for the likely possibility that HTS standards follow the wages, the share of GDP devoted to HTS could become as high as 3% at the end of 21st century.

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The role of methane in projections of 21st century stratospheric water vapour

10.5194/acp-2016-545 ◽

2016 ◽

Author(s):

Laura Revell ◽

Andrea Stenke ◽

Eugene Rozanov ◽

William Ball ◽

Stefan Lossow ◽

...

Keyword(s):

Water Vapour ◽

Methane Oxidation ◽

21St Century ◽

Radiative Forcing ◽

Lower Stratosphere ◽

Climate Model ◽

Radiative Balance ◽

Canonical Representative ◽

Cold Point ◽

Stratospheric Water Vapour

Abstract. Stratospheric water vapour (SWV) is an important component of the Earth's atmosphere as it affects both radiative balance and the chemistry of the atmosphere. Key processes driving changes in SWV through the 21st century include dehydration of air masses transiting the cold-point tropopause (CPT) and methane oxidation. Increasing surface temperatures may strengthen the Brewer-Dobson circulation, such that more methane is transported into the stratosphere where it can be oxidised to SWV. We use a chemistry-climate model to simulate changes in SWV through the 21st century following the four canonical Representative Concentration Pathways (RCPs). Furthermore, we quantify the contribution that methane oxidation makes to SWV following each of the RCPs. The methane contribution to SWV maximises in the upper stratosphere, however modelled SWV trends are found to be driven predominantly by warming of the CPT and strengthening of the Brewer-Dobson circulation rather than by increasing methane oxidation. SWV changes by −5 % to 60 % (depending on the location in the atmosphere and emissions scenario) and increases in the lower stratosphere in all RCPs through the 21st century. Because the lower stratosphere is where water vapour radiative forcing maximises, SWV's influence on surface climate is also expected to increase through the 21st century.

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"Changes" of the thermal continentality in Central Europe between the years 1951 and 2013: case study – Slovak Republic

Earth System Dynamics Discussions ◽

10.5194/esdd-6-1261-2015 ◽

2015 ◽

Vol 6 (2) ◽

pp. 1261-1275 ◽

Cited By ~ 1

Author(s):

J. Vilček ◽

J. Škvarenina ◽

J. Vido ◽

R. Kandrík ◽

J. Škvareninová ◽

...

Keyword(s):

Climate Change ◽

Central Europe ◽

21St Century ◽

Climate Model ◽

Slovak Republic ◽

Vegetation Distribution ◽

Climate Conditions ◽

Air Temperatures

Abstract. The influence of continents and oceans plays conceptually the key role in the climate conditions of Europeans regions. Continentality is also an important phytogeographic factor of vegetation distribution in Slovakia. This study analysed continentality development at six meteorological stations in Slovakia during the periods 1951–2013, or 1961–2013. Rising trend of the maximal and minimal temperature has been observed at all meteorological stations (lowland as well as mountainous stations) in this periods. However the results showed non-significant increase of continentality index during the monitored period of 63 (53) years. Based on the results of CCM 2000 climate model we cannot expect significant changes of continentality by the end of the 21st century, but the climate change will be significantly manifested by the increase of maximum and minimum air temperatures.

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Chemical and climatic drivers of radiative forcing due to changes in stratospheric and tropospheric ozone over the 21st century

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-2899-2018 ◽

2018 ◽

Vol 18 (4) ◽

pp. 2899-2911 ◽

Cited By ~ 1

Author(s):

Antara Banerjee ◽

Amanda C. Maycock ◽

John A. Pyle

Keyword(s):

Tropospheric Ozone ◽

Radiative Forcing ◽

Climate Model ◽

Stratospheric Ozone ◽

Radiative Forcings ◽

The United Kingdom ◽

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 (UK Met Office's Unified Model containing the United Kingdom Chemistry and Aerosols sub-model). Projected measures to improve air-quality through reductions in non-methane tropospheric ozone precursor emissions present a co-benefit for climate, with a net global mean ozone RF of −0.09 W m−2. This is opposed by a positive ozone RF of 0.05 W m−2 due to future decreases in ODSs, which is driven by an increase in tropospheric ozone through stratosphere-to-troposphere transport of air containing higher ozone amounts. An increase in methane abundance by more than a factor of 2 (as projected by the RCP8.5 scenario) is found to drive an ozone RF of 0.18 W m−2, which would greatly outweigh the climate benefits of non-methane tropospheric ozone precursor reductions. A small fraction (∼ 15 %) 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 gases, sea surface temperatures and sea ice changes) is shown to be dependent on the greenhouse gas emissions pathway, with a positive RF (0.05 W m−2) for RCP4.5 and a negative RF (−0.07 W m−2) for the RCP8.5 scenario. This dependence arises mainly from differences in the contribution to RF from stratospheric ozone changes. Considering the increases in tropopause height under climate change causes only small differences (≤ |0.02| W m−2) for the stratospheric, tropospheric and whole-atmosphere RFs.

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Radiative forcing of climate change from the Copernicus reanalysis of atmospheric composition

Earth System Science Data ◽

10.5194/essd-12-1649-2020 ◽

2020 ◽

Vol 12 (3) ◽

pp. 1649-1677 ◽

Cited By ~ 2

Author(s):

Nicolas Bellouin ◽

Will Davies ◽

Keith P. Shine ◽

Johannes Quaas ◽

Johannes Mülmenstädt ◽

...

Keyword(s):

Climate Change ◽

Carbon Dioxide ◽

Tropospheric Ozone ◽

Radiative Forcing ◽

Stratospheric Ozone ◽

Atmospheric Composition ◽

Global Average ◽

Aerosol Cloud ◽

Aerosol Cloud Interactions ◽

The Impact

Abstract. Radiative forcing provides an important basis for understanding and predicting global climate changes, but its quantification has historically been done independently for different forcing agents, has involved observations to varying degrees, and studies have not always included a detailed analysis of uncertainties. The Copernicus Atmosphere Monitoring Service reanalysis is an optimal combination of modelling and observations of atmospheric composition. It provides a unique opportunity to rely on observations to quantify the monthly and spatially resolved global distributions of radiative forcing consistently for six of the largest forcing agents: carbon dioxide, methane, tropospheric ozone, stratospheric ozone, aerosol–radiation interactions, and aerosol–cloud interactions. These radiative-forcing estimates account for adjustments in stratospheric temperatures but do not account for rapid adjustments in the troposphere. On a global average and over the period 2003–2017, stratospherically adjusted radiative forcing of carbon dioxide has averaged +1.89 W m−2 (5 %–95 % confidence interval: 1.50 to 2.29 W m−2) relative to 1750 and increased at a rate of 18 % per decade. The corresponding values for methane are +0.46 (0.36 to 0.56) W m−2 and 4 % per decade but with a clear acceleration since 2007. Ozone radiative-forcing averages +0.32 (0 to 0.64) W m−2, almost entirely contributed by tropospheric ozone since stratospheric ozone radiative forcing is only +0.003 W m−2. Aerosol radiative-forcing averages −1.25 (−1.98 to −0.52) W m−2, with aerosol–radiation interactions contributing −0.56 W m−2 and aerosol–cloud interactions contributing −0.69 W m−2 to the global average. Both have been relatively stable since 2003. Taking the six forcing agents together, there is no indication of a sustained slowdown or acceleration in the rate of increase in anthropogenic radiative forcing over the period. These ongoing radiative-forcing estimates will monitor the impact on the Earth's energy budget of the dramatic emission reductions towards net-zero that are needed to limit surface temperature warming to the Paris Agreement temperature targets. Indeed, such impacts should be clearly manifested in radiative forcing before being clear in the temperature record. In addition, this radiative-forcing dataset can provide the input distributions needed by researchers involved in monitoring of climate change, detection and attribution, interannual to decadal prediction, and integrated assessment modelling. The data generated by this work are available at https://doi.org/10.24380/ads.1hj3y896 (Bellouin et al., 2020b).

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

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-9647-2010 ◽

2010 ◽

Vol 10 (4) ◽

pp. 9647-9694 ◽

Cited By ~ 3

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.

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The role of methane in projections of 21st century stratospheric water vapour

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-13067-2016 ◽

2016 ◽

Vol 16 (20) ◽

pp. 13067-13080 ◽

Cited By ~ 12

Author(s):

Laura E. Revell ◽

Andrea Stenke ◽

Eugene Rozanov ◽

William Ball ◽

Stefan Lossow ◽

...

Keyword(s):

Water Vapour ◽

Methane Oxidation ◽

21St Century ◽

Radiative Forcing ◽

Lower Stratosphere ◽

Climate Model ◽

Radiative Balance ◽

Canonical Representative ◽

Cold Point ◽

Stratospheric Water Vapour

Abstract. Stratospheric water vapour (SWV) is an important component of the Earth's atmosphere as it affects both radiative balance and the chemistry of the atmosphere. Key processes driving changes in SWV include dehydration of air masses transiting the cold-point tropopause (CPT) and methane oxidation. We use a chemistry–climate model to simulate changes in SWV through the 21st century following the four canonical representative concentration pathways (RCPs). Furthermore, we quantify the contribution that methane oxidation makes to SWV following each of the RCPs. Although the methane contribution to SWV maximizes in the upper stratosphere, modelled SWV trends are found to be driven predominantly by warming of the CPT rather than by increasing methane oxidation. SWV changes by −5 to 60 % (depending on the location in the atmosphere and emissions scenario) and increases in the lower stratosphere in all RCPs through the 21st century. Because the lower stratosphere is where water vapour radiative forcing maximizes, SWV's influence on surface climate is also expected to increase through the 21st century.

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