EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Greenhouse gas metrics for net zero targets in science and policy

Alexander Nauels1,2, Carl-Friedrich Schleussner1,3,4, and Joeri Rogelj5,6,7
Alexander Nauels et al.
  • 1Climate Analytics, Berlin, Germany
  • 2Australian-German Climate & Energy College, The University of Melbourne, Parkville, VIC 3010, Australia
  • 3Potsdam Institute for Climate Impact Research, D-14412 Potsdam, Germany
  • 4Integrative Research Institute on Transformations of Human–Environment Systems (IRI THESys), Humboldt-Universität zu Berlin, 10099 Berlin, Germany
  • 5Grantham Institute for Climate Change and the Environment, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
  • 6International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
  • 7Institute for Atmospheric and Climate Science, ETH Zurich, Universitätstrasse 16, 8006 Zurich, Switzerland

The treatment of non-CO2 greenhouse gases is central for scientific assessments of effective climate change mitigation and climate policy. Radiative forcing of a unit of emitted short-lived gases decays quickly; on the order of a decade for methane, as opposed to centuries for CO2. Metric selection for comparing the climate effect of these emissions with CO2 thereby comes with choices regarding short- vs. long-term priorities to achieve mitigation. The global nature of the well-mixed atmosphere also has implications for the transferability of concepts such as global warming potentials from the global to the national scale.

Here we present the implications of metric choice on global emissions balance and net zero, with a particular emphasis on the consistency with the wider context of the Paris Agreement, both on the global as well as the national level. Stylized scenarios show that interpreting the Paris Agreement emissions goals with metrics different from the IPCC AR5 can lead to inconsistencies with the Agreement’s temperature goal. Furthermore, we illustrate that introducing metrics that depend on historical emissions in a national context raises profound questions of equity and fairness, thereby questioning the applicability of non-constant global warming potentials at any but the global level. We provide suggestions to adequately approach these issues in the context of the Paris Agreement and national policy making.

How to cite: Nauels, A., Schleussner, C.-F., and Rogelj, J.: Greenhouse gas metrics for net zero targets in science and policy, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10816,, 2021.


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