Historical (1850–2014) Aerosol Evolution and Role on Climate Forcing Using the GISS ModelE2.1 Contribution to CMIP6

Bauer, Susanne E.; Tsigaridis, Kostas; Faluvegi, G.; Kelley, M. E.; Lo, K.; Miller, Ron; Nazarenko, Larissa; Schmidt, Gavin A.; Wu, Jingbo

doi:10.1029/2019ms001978

Cited by 91 publications

(97 citation statements)

References 119 publications

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“…A large diversity in the historical change in surface O 3 was simulated by CMIP6 models across South Asia and other Northern Hemisphere regions. CMIP6 models predicted larger historical changes in surface O 3 than those from an emissiononly-driven parameterisation, indicating a potential climate change impact (Wu et al, 2008;Bloomer et al, 2009;Weaver et al, 2009;Rasmussen et al, 2013;Colette et al, 2015) on surface O 3 over the historical period. Small global increases in surface PM 2.5 are simulated over the historical period by CMIP6 models, with larger regional changes of up to 12 µg m −3 on an annual mean basis and up to 18 µg m −3 in DJF across East and South Asia.…”

Section: Discussionmentioning

confidence: 95%

Historical and future changes in air pollutants from CMIP6 models

et al. 2020

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Abstract. Poor air quality is currently responsible for large impacts on human health across the world. In addition, the air pollutants ozone (O3) and particulate matter less than 2.5 µm in diameter (PM2.5) are also radiatively active in the atmosphere and can influence Earth's climate. It is important to understand the effect of air quality and climate mitigation measures over the historical period and in different future scenarios to ascertain any impacts from air pollutants on both climate and human health. The Coupled Model Intercomparison Project Phase 6 (CMIP6) presents an opportunity to analyse the change in air pollutants simulated by the current generation of climate and Earth system models that include a representation of chemistry and aerosols (particulate matter). The shared socio-economic pathways (SSPs) used within CMIP6 encompass a wide range of trajectories in precursor emissions and climate change, allowing for an improved analysis of future changes to air pollutants. Firstly, we conduct an evaluation of the available CMIP6 models against surface observations of O3 and PM2.5. CMIP6 models consistently overestimate observed surface O3 concentrations across most regions and in most seasons by up to 16 ppb, with a large diversity in simulated values over Northern Hemisphere continental regions. Conversely, observed surface PM2.5 concentrations are consistently underestimated in CMIP6 models by up to 10 µg m−3, particularly for the Northern Hemisphere winter months, with the largest model diversity near natural emission source regions. The biases in CMIP6 models when compared to observations of O3 and PM2.5 are similar to those found in previous studies. Over the historical period (1850–2014) large increases in both surface O3 and PM2.5 are simulated by the CMIP6 models across all regions, particularly over the mid to late 20th century, when anthropogenic emissions increase markedly. Large regional historical changes are simulated for both pollutants across East and South Asia with an annual mean increase of up to 40 ppb for O3 and 12 µg m−3 for PM2.5. In future scenarios containing strong air quality and climate mitigation measures (ssp126), annual mean concentrations of air pollutants are substantially reduced across all regions by up to 15 ppb for O3 and 12 µg m−3 for PM2.5. However, for scenarios that encompass weak action on mitigating climate and reducing air pollutant emissions (ssp370), annual mean increases in both surface O3 (up 10 ppb) and PM2.5 (up to 8 µg m−3) are simulated across most regions, although, for regions like North America and Europe small reductions in PM2.5 are simulated due to the regional reduction in precursor emissions in this scenario. A comparison of simulated regional changes in both surface O3 and PM2.5 from individual CMIP6 models highlights important regional differences due to the simulated interaction of aerosols, chemistry, climate and natural emission sources within models. The projection of regional air pollutant concentrations from the latest climate and Earth system models used within CMIP6 shows that the particular future trajectory of climate and air quality mitigation measures could have important consequences for regional air quality, human health and near-term climate. Differences between individual models emphasise the importance of understanding how future Earth system feedbacks influence natural emission sources, e.g. response of biogenic emissions under climate change.

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Section: Discussionmentioning

confidence: 95%

Historical and future changes in air pollutants from CMIP6 models

et al. 2020

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“…Carslaw et al (2010) reviewed climate feedbacks involving natural and anthropogenic aerosols. Climate change can impact both the source strength of natural aerosols such as sea salt, dust, biomass burning aerosols or their precursors (dimethyl sulfide (DMS), biogenic volatile organic compounds) and the lifetime of natural and anthropogenic aerosols through changes in transport and dry and wet deposition (Bellouin et al, 2011;Raes et al, 2010). Here, we choose to focus especially on those feedbacks that are mediated through changes in the abundances of reactive gases and aerosols, using data from CMIP6 (Coupled Model Intercomparison Project phase 6) (Eyring et al, 2016) Earth system models that conducted the AerChemMIP (Aerosols and Chemistry Model Intercomparison Project) simulations (Collins et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Climate-driven chemistry and aerosol feedbacks in CMIP6 Earth system models

et al. 2021

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Abstract. Feedbacks play a fundamental role in determining the magnitude of the response of the climate system to external forcing, such as from anthropogenic emissions. The latest generation of Earth system models includes aerosol and chemistry components that interact with each other and with the biosphere. These interactions introduce a complex web of feedbacks that is important to understand and quantify. This paper addresses multiple pathways for aerosol and chemical feedbacks in Earth system models. These focus on changes in natural emissions (dust, sea salt, dimethyl sulfide, biogenic volatile organic compounds (BVOCs) and lightning) and changes in reaction rates for methane and ozone chemistry. The feedback terms are then given by the sensitivity of a pathway to climate change multiplied by the radiative effect of the change. We find that the overall climate feedback through chemistry and aerosols is negative in the sixth Coupled Model Intercomparison Project (CMIP6) Earth system models due to increased negative forcing from aerosols in a climate with warmer surface temperatures following a quadrupling of CO2 concentrations. This is principally due to increased emissions of sea salt and BVOCs which are sensitive to climate change and cause strong negative radiative forcings. Increased chemical loss of ozone and methane also contributes to a negative feedback. However, overall methane lifetime is expected to increase in a warmer climate due to increased BVOCs. Increased emissions of methane from wetlands would also offset some of the negative feedbacks. The CMIP6 experimental design did not allow the methane lifetime or methane emission changes to affect climate, so we found a robust negative contribution from interactive aerosols and chemistry to climate sensitivity in CMIP6 Earth system models.

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“…OMA (“One‐Moment Aerosols”): a fully interactive chemistry configuration, described in Bauer et al. (2020). OMA submissions to CMIP6 were denoted as “physics version 3” on the Earth System Grid Federation.…”

Section: Methodsmentioning

confidence: 99%