The Impact of Stratospheric Ozone Feedbacks on Climate Sensitivity Estimates

Nowack, Peer; Abraham, N. L.; Braesicke, Peter; Pyle, J. A.

doi:10.1002/2017jd027943

Cited by 30 publications

(45 citation statements)

References 79 publications

(152 reference statements)

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“…The impact of stratospheric ozone on the surface climate in the LGM as well as the MH implies that the stratospheric ozone profile is an important factor for paleoclimate simulations of any periods for which the CO 2 concentrations and orbital elements vary substantially. The consistent climate responses to chemistry feedbacks associated with changes in CO 2 concentration between our LGM (reduced CO 2 ) simulation and abrupt 4xCO 2 experiments (Nowack et al, , ) suggest that chemical feedbacks in the paleoclimate simulations can be used for a validation of ESMs for global warming simulations.…”

Section: Discussionsupporting

confidence: 70%

Mitigation of Global Cooling by Stratospheric Chemistry Feedbacks in a Simulation of the Last Glacial Maximum

et al. 2018

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The impact of changes in the stratospheric ozone profile in the Last Glacial Maximum simulation under reduced atmospheric CO2 concentrations and different orbital elements is investigated using an Earth System Model. For this, simulations including an interactive atmospheric chemistry scheme is compared with simulations using the prescribed ozone profile for a preindustrial control run of the fifth Coupled Model Intercomparison Project (CMIP5). The contribution of the interactive chemistry reveals a significant warming of zonal mean surface temperature, +0.5 K (approximately 20%) in the tropics and up to +1.6 K in high latitudes. In the tropics, this mitigation of global cooling is related to longwave radiative feedbacks associated with circulation‐driven increases in the lower stratospheric ozone and in the stratospheric water vapor, and related decrease in cirrus clouds. The mechanisms are of opposite sign to and consistent with those obtained by increased CO2 simulations. In high latitude, the stronger mitigation of cooling is associated with sea ice retreat, which has the same sign to and is consistent with our previous paleoclimate simulation of the mid‐Holocene (CO2 concentration of 280 ppm and orbital element change) including interactive chemistry. Most previous Last Glacial Maximum simulations with the prescribed ozone profile exhibited cold bias in the tropics compared with geological proxy data, whereas this bias is reduced in our simulations through the use of the interactive ozone chemistry , although a warmer bias in the midlatitude is enhanced. We recommend climate models to include ozone profiles that are consistent with CO2 concentrations and solar forcing.

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Section: Discussionsupporting

confidence: 70%

Mitigation of Global Cooling by Stratospheric Chemistry Feedbacks in a Simulation of the Last Glacial Maximum

et al. 2018

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“…Spatial distribution and intensity of these changes look very similar over all tropical latitudes and most of the stratosphere. They agree to expected changes in ozone under abrupt‐4xCO2 experiments (see, for instance, Nowack et al, ). Setting the

A_{4}

coefficient (dependence of ozone evolution to temperature) to 0 resulted in a very different ozone field under 4xCO2Clim‐4xCO2 conditions through most of the stratosphere, with smaller evolutions from the control simulation than those of CNRM‐CM6‐1 (see Figure ).…”

Section: Sensitivity To Co 2 and Historical Evolutionssupporting

confidence: 90%

Present‐Day and Historical Aerosol and Ozone Characteristics in CNRM CMIP6 Simulations

Michou

Nabat

Saint‐Martin

et al. 2020

J Adv Model Earth Syst

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Characteristics and radiative forcing of the aerosol and ozone fields of two configurations of the Centre National de Recherches Météoroglogiques (CNRM) and Cerfacs climate model are analyzed over the historical period (1850-2014), using several Coupled Model Intercomparison Project 6 (CMIP6) simulations. CNRM-CM6-1 is the atmosphere-ocean general circulation model including prescribed aerosols and a linear stratospheric ozone scheme, while the Earth System Model CNRM-ESM2-1 has interactive tropospheric aerosols and chemistry of the midtroposphere aloft. The representations of aerosols and ozone in CNRM-CM6-1 are issued from simulations of CNRM-ESM2-1, and this ensures some comparability of both representations. In particular, present-day anthropogenic aerosol optical depths are similar (0.018), and their spatial patterns correspond to those of reference data sets such as MACv2 and MACv2-SP despite a negative bias. Effective radiative forcings (ERFs) have been estimated using 30-year fixed sea surface temperature simulations (piClim) and several calls to the radiative scheme. Present-day anthropogenic aerosol ERF, aerosol-radiation ERF, and aerosol cloud ERF are fully within CMIP5 estimates and, respectively, equal to −1.10, −0.36, and −0.81 W m −2 for CNRM-CM6-1 and −0.21, −0.61, and −0.74 W m −2 for CNRM-ESM2-1. Additional CMIP6-type piClim simulations show that these differences are mainly due to the interactivity of the aerosol scheme whose impact is confirmed when assessing the response of both climate model configurations to rising CO 2 . Present-day stratospheric ozone ERF, equal to −0.04 W m −2 , is in agreement with that of the CMIP6 ozone. No trend appears in the ozone ERF over the historical period although the evolution of the total column ozone is correctly simulated. Plain Language SummaryThe manuscript documents the Météo-France Centre National de Recherches Météorologiques aerosol-chemistry modeling contributions to the sixth Coupled Model Intercomparison Project that supports the sixth IPCC Assessment Report of climate change. It establishes that their results are suitable for use by the scientific community in the analysis of the sixth Coupled Model Intercomparison Project experiments. The authors provide an evaluation of the model performance in both present-day and historical (1850-2014) contexts, as well as a detailed analysis of the model calculated effective radiative forcing due to ozone and aerosols.

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“…It has recently been suggested that stratospheric ozone feedbacks can reduce-by up to 20%-the climate sensitivity (Nowack et al 2015), quantified as the global-mean surface temperature response to abrupt quadrupling of CO 2 (hereafter 4 3 CO 2 ). Ozone feedbacks have also been shown to influence the tropospheric circulation response to CO 2 , such as a reduction in the poleward shift of the Southern Hemisphere (SH) jet (Chiodo and Polvani 2017), and a strengthening of the Walker circulation (Nowack et al 2017). However, the magnitude of these feedbacks appears to be model dependent.…”

Section: Introductionmentioning

confidence: 99%

“…However, the magnitude of these feedbacks appears to be model dependent. Most notably, the effect of ozone on climate sensitivity ranges from 20% (Nowack et al 2015), to 7%-8% (Dietmüller et al 2014;Muthers et al 2014), to nil (Marsh et al 2016). Understanding the origin of this intermodel spread is of crucial importance toward determining whether ozone chemistry feedbacks can significantly contribute to intermodel spread in climate sensitivity.…”

Section: Introductionmentioning

confidence: 99%

The Response of the Ozone Layer to Quadrupled CO2 Concentrations: Implications for Climate

Chiodo

Polvani

2019

Journal of Climate

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The quantification of the climate impacts exerted by stratospheric ozone changes in abrupt 4 3 CO 2 forcing experiments is an important step in assessing the role of the ozone layer in the climate system. Here, we build on our previous work on the change of the ozone layer under 4 3 CO 2 and examine the effects of ozone changes on the climate response to 4 3 CO 2 , using the Whole Atmosphere Community Climate Model. We show that the global-mean radiative perturbation induced by the ozone changes under 4 3 CO 2 is small, due to nearly total cancellation between high and low latitudes, and between longwave and shortwave fluxes. Consistent with the small global-mean radiative perturbation, the effect of ozone changes on the global-mean surface temperature response to 4 3 CO 2 is negligible. However, changes in the ozone layer due to 4 3 CO 2 have a considerable impact on the tropospheric circulation. During boreal winter, we find significant ozoneinduced tropospheric circulation responses in both hemispheres. In particular, ozone changes cause an equatorward shift of the North Atlantic jet, cooling over Eurasia, and drying over northern Europe. The ozone signals generally oppose the direct effects of increased CO 2 levels and are robust across the range of ozone changes imposed in this study. Our results demonstrate that stratospheric ozone changes play a considerable role in shaping the atmospheric circulation response to CO 2 forcing in both hemispheres and should be accounted for in climate sensitivity studies.

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The Impact of Stratospheric Ozone Feedbacks on Climate Sensitivity Estimates

Cited by 30 publications

References 79 publications

Mitigation of Global Cooling by Stratospheric Chemistry Feedbacks in a Simulation of the Last Glacial Maximum

Mitigation of Global Cooling by Stratospheric Chemistry Feedbacks in a Simulation of the Last Glacial Maximum

Present‐Day and Historical Aerosol and Ozone Characteristics in CNRM CMIP6 Simulations

The Response of the Ozone Layer to Quadrupled CO2 Concentrations: Implications for Climate

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