Year: 2020
Type: article
Abstract: The radiative forcing from aerosols (particularly through their interaction with clouds) remains one of the most uncertain components of the human forcing of the climate. Observation-based studies have typically found a smaller aerosol effective radiative forcing than in model simulations and were given preferential weighting in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). With their own sources of uncertainty, it is not clear that observation-based estimates are more reliable. Understanding the source of the model and observational differences is thus vital to reduce uncertainty in the impact of aerosols on the climate. These reported discrepancies arise from the different methods of separating the components of aerosol forcing used in model and observational studies. Applying the observational decomposition to global climate model (GCM) output, the two different lines of evidence are surprisingly similar, with a much better agreement on the magnitude of aerosol impacts on cloud properties. Cloud adjustments remain a significant source of uncertainty, particularly for ice clouds. However, they are consistent with the uncertainty from observation-based methods, with the liquid water path adjustment usually enhancing the Twomey effect by less than 50%. Depending on different sets of assumptions, this work suggests that model and observation-based estimates could be more equally weighted in future synthesis studies.
Institutions: Imperial College London, Pacific Northwest National Laboratory, Leipzig University, NSF National Center for Atmospheric Research, Met Office, University of Exeter, ETH Zurich, Institute for Atmospheric and Climate Science, University of Oxford, Kyushu University, Jiangsu Collaborative Innovation Center for Climate Change, Nanjing University
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $1,725
Funders: U.S. Department of Energy, National Aeronautics and Space Administration, Battelle, Deutsches Klimarechenzentrum, Imperial College London, University of Oxford, European Commission, Deutsche Forschungsgemeinschaft, Eidgenössische Technische Hochschule Zürich, Forschungszentrum Jülich, National Institute for Environmental Studies, Centro Svizzero di Calcolo Scientifico, National Supercomputing Centre Singapore, Office of Science, Natural Environment Research Council, Japan Society for the Promotion of Science, Biological and Environmental Research, H2020 European Research Council, Pacific Northwest National Laboratory
Awards: G1242655424, G135623947, G1756126698, Sophistication of climate change prediction of the numerical model by aerosol terrestrial remote sensing observation network, Global Aerosol Synthesis and Science Project (GASSP) to reduce the uncertainty in aerosol radiative forcing, G2423612313, Assessment on climate impacts of short-lived climate forcers by composition and region with hierarchical numerical models, G2988778103, G300640497, G3269889816, The Aerosol-Cloud Uncertainty REduction project (A-CURE), G3933667097, G434337789, G538270251, G5726405315, South American Biomass Burning Analysis (SAMBBA), CLouds and Aerosol Radiative Impacts and Forcing: Year 2016 (CLARIFY-2016), G7578079922, G7776018454, G8175880974, SWAAMI (South West Asian Aerosol Monsoon Interactions), G84288863
OpenAlex ID: W2953530608