title: Disentangling the effects of CO2 and short-lived climate forcer mitigation.
abstract: Anthropogenic global warming is driven by emissions of a wide variety of radiative forcers ranging from very short-lived climate forcers (SLCFs), like black carbon, to very long-lived, like CO2. These species are often released from common sources and are therefore intricately linked. However, for reasons of simplification, this CO2-SLCF linkage was often disregarded in long-term projections of earlier studies. Here we explicitly account for CO2-SLCF linkages and show that the short- and long-term climate effects of many SLCF measures consistently become smaller in scenarios that keep warming to below 2 °C relative to preindustrial levels. Although long-term mitigation of methane and hydrofluorocarbons are integral parts of 2 °C scenarios, early action on these species mainly influences near-term temperatures and brings small benefits for limiting maximum warming relative to comparable reductions taking place later. Furthermore, we find that maximum 21st-century warming in 2 °C-consistent scenarios is largely unaffected by additional black-carbon-related measures because key emission sources are already phased-out through CO2 mitigation. Our study demonstrates the importance of coherently considering CO2-SLCF coevolutions. Failing to do so leads to strongly and consistently overestimating the effect of SLCF measures in climate stabilization scenarios. Our results reinforce that SLCF measures are to be considered complementary rather than a substitute for early and stringent CO2 mitigation. Near-term SLCF measures do not allow for more time for CO2 mitigation. We disentangle and resolve the distinct benefits across different species and therewith facilitate an integrated strategy for mitigating both short and long-term climate change.
authors.affiliation: Institute for Atmospheric and Climate Science, ETH Zurich, 8092 Zürich, Switzerland; Energy Program and Mitigation of Air Pollution & Greenhouse Gases Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria; john@pik-potsdam.de rogelj@iiasa.ac.at.
authors.forename: Joeri
authors.initials: J
authors.lastname: Rogelj
authors.affiliation: Climate Analytics gGmbH, 10969 Berlin, Germany; Environmental Systems Analysis Group, Wageningen University and Research Centre, 6700 AA Wageningen, The Netherlands;
authors.forename: Michiel
authors.initials: M
authors.lastname: Schaeffer
authors.affiliation: School of Earth Sciences, The University of Melbourne, 3010 Melbourne, VIC, Australia; Potsdam Institute for Climate Impact Research, 14412 Potsdam, Germany;
authors.forename: Malte
authors.initials: M
authors.lastname: Meinshausen
authors.affiliation: Nicholas School of the Environment, Duke University, Durham, NC 27708;
authors.forename: Drew T
authors.initials: DT
authors.lastname: Shindell
authors.affiliation: Climate Analytics gGmbH, 10969 Berlin, Germany; Potsdam Institute for Climate Impact Research, 14412 Potsdam, Germany;
authors.forename: William
authors.initials: W
authors.lastname: Hare
authors.affiliation: Energy Program and Mitigation of Air Pollution & Greenhouse Gases Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria;
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Klimont
authors.affiliation: National Institute for Public Health and the Environment (RIVM), 3720 BA Bilthoven, The Netherlands; and.
authors.forename: Guus J M
authors.identifier: http://orcid.org/0000-0002-6597-7088
authors.initials: GJ
authors.lastname: Velders
authors.affiliation: Energy Program and Mitigation of Air Pollution & Greenhouse Gases Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria;
authors.forename: Markus
authors.initials: M
authors.lastname: Amann
authors.affiliation: Potsdam Institute for Climate Impact Research, 14412 Potsdam, Germany; Santa Fe Institute, Santa Fe, NM 87501 john@pik-potsdam.de rogelj@iiasa.ac.at.
authors.forename: Hans Joachim
authors.initials: HJ
authors.lastname: Schellnhuber
keywords: air pollution; black carbon; carbon dioxide; climate change mitigation; short-lived climate forcers