The global aerosol–climate model ECHAM6.3–HAM2.3 – Part 2: Cloud evaluation, aerosol radiative forcing, and climate sensitivity

Neubauer, David; Ferrachat, Sylvaine; Drian, Colombe Siegenthaler-Le; Stier, Philip; Partridge, Daniel G.; Tegen, Ina; Bey, I.; Stanelle, Tanja; Kokkola, Harri; Lohmann, Ulrike

doi:10.5194/gmd-12-3609-2019

Cited by 91 publications

(99 citation statements)

References 109 publications

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“…Overall, nine coupled ocean-atmosphere climate models performed the SSP3-7.0 and SSP3-7.0-lowNTCF simulations, including CNRM-ESM2-1 (Séférian et al, 2019;Michou et al, 2019), MIROC6 (Takemura et al, 2005(Takemura et al, , 2009Tatebe et al, 2019), MPI-ESM1-2-HAM (Mauritsen et al, 2019;Neubauer et al, 2019;Tegen et al, 2019), NorESM2-LM (Seland et al, 2020), BCC-ESM1 (Wu et al, 2019(Wu et al, , 2020, GFDL-ESM4 (John et al, 2018;Horowitz et al, 2018;Dunne et al, 2020;Horowitz et al, 2020), CESM2-WACCM (Emmons et al, 2020;Gettelman et al, 2019;Tilmes et al, 2019), UKESM1-0-LL (Sellar et al, 2019), and MRI-ESM2-0 (Yukimoto et al, 2019). However, the first four models (CNRM-ESM2-1, MIROC6, MPI-ESM1-2-HAM, NorESM2-LM) lack interactive tropospheric chemistry schemes and therefore include identical ozone evolution in both SSP3-7.0 and SSP3-7.0-lowNTCF simulations (as recommended by AerChemMIP).…”

Section: Aerchemmip Modelsmentioning

confidence: 99%

Climate and air quality impacts due to mitigation of non-methane near-term climate forcers

et al. 2020

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Abstract. It is important to understand how future environmental policies will impact both climate change and air pollution. Although targeting near-term climate forcers (NTCFs), defined here as aerosols, tropospheric ozone, and precursor gases, should improve air quality, NTCF reductions will also impact climate. Prior assessments of the impact of NTCF mitigation on air quality and climate have been limited. This is related to the idealized nature of some prior studies, simplified treatment of aerosols and chemically reactive gases, as well as a lack of a sufficiently large number of models to quantify model diversity and robust responses. Here, we quantify the 2015–2055 climate and air quality effects of non-methane NTCFs using nine state-of-the-art chemistry–climate model simulations conducted for the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP). Simulations are driven by two future scenarios featuring similar increases in greenhouse gases (GHGs) but with “weak” (SSP3-7.0) versus “strong” (SSP3-7.0-lowNTCF) levels of air quality control measures. As SSP3-7.0 lacks climate policy and has the highest levels of NTCFs, our results (e.g., surface warming) represent an upper bound. Unsurprisingly, we find significant improvements in air quality under NTCF mitigation (strong versus weak air quality controls). Surface fine particulate matter (PM2.5) and ozone (O3) decrease by -2.2±0.32 µg m−3 and -4.6±0.88 ppb, respectively (changes quoted here are for the entire 2015–2055 time period; uncertainty represents the 95 % confidence interval), over global land surfaces, with larger reductions in some regions including south and southeast Asia. Non-methane NTCF mitigation, however, leads to additional climate change due to the removal of aerosol which causes a net warming effect, including global mean surface temperature and precipitation increases of 0.25±0.12 K and 0.03±0.012 mm d−1, respectively. Similarly, increases in extreme weather indices, including the hottest and wettest days, also occur. Regionally, the largest warming and wetting occurs over Asia, including central and north Asia (0.66±0.20 K and 0.03±0.02 mm d−1), south Asia (0.47±0.16 K and 0.17±0.09 mm d−1), and east Asia (0.46±0.20 K and 0.15±0.06 mm d−1). Relatively large warming and wetting of the Arctic also occur at 0.59±0.36 K and 0.04±0.02 mm d−1, respectively. Similar surface warming occurs in model simulations with aerosol-only mitigation, implying weak cooling due to ozone reductions. Our findings suggest that future policies that aggressively target non-methane NTCF reductions will improve air quality but will lead to additional surface warming, particularly in Asia and the Arctic. Policies that address other NTCFs including methane, as well as carbon dioxide emissions, must also be adopted to meet climate mitigation goals.

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Section: Aerchemmip Modelsmentioning

confidence: 99%

Climate and air quality impacts due to mitigation of non-methane near-term climate forcers

et al. 2020

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“…Eight coupled ocean-atmosphere climate models performed the SSP3-7.0 and SSP3-7.0-lowNTCF simulations, including 110 CNRM-ESM2-1 (Séférian et al, 2019;Michou et al, 2019), MIROC6 (Takemura et al, 2005(Takemura et al, , 2009Tatebe et al, 2019), MPI-ESM1-2-HAM (Mauritsen et al, 2019;Neubauer et al, 2019;Tegen et al, 2019), BCC-ESM1 (Wu et al, 2019, submitted), In prep. ;Horowitz and et al,In prep.…”

Section: Aerchemmip Modelsmentioning

confidence: 99%

Climate and air quality impacts due to mitigation of non-methane near-term climate forcers

Allen¹,

Turnock²,

Nabat³

et al. 2020

Preprint

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Abstract. Over the next few decades, policies that optimally address both climate change and air quality are essential. Although targeting near-term climate forcers (NTCFs), defined here as aerosols, tropospheric ozone and precursor gases (but not methane), should improve air quality, NTCF reductions will also impact climate. How future policies affect the abundance of NTCFs and their impact on climate and air quality remains uncertain. Here, we quantify the 2015&#8211;2055 climate and air quality effects of non-methane NTCFs using state-of-the-art chemistry-climate model simulations conducted for the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP). Simulations are driven by two future scenarios featuring similar increases in greenhouse gases (GHGs) but with <q>weak</q> versus <q>strong</q> levels of air quality control measures. Unsurprisingly, we find significant improvements in air quality under NTCF mitigation (strong versus weak air quality controls). Surface ozone (O3) and fine particulate matter (PM2.5) decrease by &#8722;15&#8201;% and &#8722;25&#8201;%, respectively, over global land surfaces, with larger reductions in some regions including south and southeast Asia. Non-methane NTCF mitigation, however, leads to additional climate change due to the removal of aerosol which causes a net warming effect, including global mean surface temperature and precipitation increases of 0.24&#8201;K and 1.1&#8201;%, respectively, with similar increases in extreme weather indices. Regionally, the largest warming and wetting trends occur over Asia, including central and north Asia (0.56&#8201;K and 2.1&#8201;%), south Asia (0.48&#8201;K and 4.6&#8201;%) and east Asia (0.44&#8201;K and 4.7&#8201;%). Relatively large warming and wetting of the Arctic also occurs at 0.41&#8201;K and 2.1&#8201;%, respectively. Similar surface warming occurs in model simulations with aerosol-only mitigation, implying weak cooling due to ozone reductions. Our findings suggest that future policies that aggressively target non-methane NTCF reductions will improve air quality, but will lead to additional surface warming, particularly in Asia and the Arctic. Policies that address other NTCFs including methane, as well as carbon dioxide emissions, must also be adopted to meet mitigation goals.

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“…Also, Kulkarni et al (2016) analyzed the ice formation ability of diesel soot under cirrus conditions and reported a 1 % frozen fraction of the soot particles at similar ice saturation ratios. Nichman et al (2019) examined six types of BC particles considered as proxies for atmospheric BC and found onset saturation thresholds for ice nucleation between 1.1 and 1.5. Recent studies observed BC nucleation at cirrus temperatures but explained it with pore condensation and freezing rather than with deposition nucleation (Wagner et al, 2016;Marcolli, 2017;Mahrt et al, 2018;David et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Coupling aerosols to (cirrus) clouds in the global EMAC-MADE3 aerosol–climate model

Righi

Hendricks

Lohmann³

et al. 2020

Geosci. Model Dev.

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Abstract. A new cloud microphysical scheme including a detailed parameterization for aerosol-driven ice formation in cirrus clouds is implemented in the global ECHAM/MESSy Atmospheric Chemistry (EMAC) chemistry–climate model and coupled to the third generation of the Modal Aerosol Dynamics model for Europe adapted for global applications (MADE3) aerosol submodel. The new scheme is able to consistently simulate three regimes of stratiform clouds – liquid, mixed-, and ice-phase (cirrus) clouds – considering the activation of aerosol particles to form cloud droplets and the nucleation of ice crystals. In the cirrus regime, it allows for the competition between homogeneous and heterogeneous freezing for the available supersaturated water vapor, taking into account different types of ice-nucleating particles, whose specific ice-nucleating properties can be flexibly varied in the model setup. The new model configuration is tuned to find the optimal set of parameters that minimizes the model deviations with respect to observations. A detailed evaluation is also performed comparing the model results for standard cloud and radiation variables with a comprehensive set of observations from satellite retrievals and in situ measurements. The performance of EMAC-MADE3 in this new coupled configuration is in line with similar global coupled models and with other global aerosol models featuring ice cloud parameterizations. Some remaining discrepancies, namely a high positive bias in liquid water path in the Northern Hemisphere and overestimated (underestimated) cloud droplet number concentrations over the tropical oceans (in the extratropical regions), which are both a common problem in these kinds of models, need to be taken into account in future applications of the model. To further demonstrate the readiness of the new model system for application studies, an estimate of the anthropogenic aerosol effective radiative forcing (ERF) is provided, showing that EMAC-MADE3 simulates a relatively strong aerosol-induced cooling but within the range reported in the Intergovernmental Panel on Climate Change (IPCC) assessments.

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The global aerosol–climate model ECHAM6.3–HAM2.3 – Part 2: Cloud evaluation, aerosol radiative forcing, and climate sensitivity

Cited by 91 publications

References 109 publications

Climate and air quality impacts due to mitigation of non-methane near-term climate forcers

Climate and air quality impacts due to mitigation of non-methane near-term climate forcers

Climate and air quality impacts due to mitigation of non-methane near-term climate forcers

Coupling aerosols to (cirrus) clouds in the global EMAC-MADE3 aerosol–climate model

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