2019/10/15 by Steve Denison, Piers Forster, Chris Smith · 2 citations
Economics, Econometrics and Finance · Environmental Science · Earth and Planetary Sciences · #Climate Change Policy and Economics #Atmospheric and Environmental Gas Dynamics #Atmospheric chemistry and aerosols
paper · pdf · doi:10.1088/1748-9326/ab4df4
openalex publication_date 2019/10/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Abstract Many nationally determined contributions (NDCs) under the Paris Agreement follow the established practice of specifying emissions levels in tonnes of CO 2 equivalent emissions. The Global Warming Potential (GWP) is the emissions metric used most often to aggregate contributions from different greenhouse gases (GHGs). However, the climate impact of pathways expressed in this way is known to be ambiguous. For this reason, alternatives have been proposed but the ambiguity has not been quantified in the context of the Paris Agreement. Here we assess the variation in temperature using pathways consistent with the ambition of limiting temperature increases to well below 2 °C. These are taken from the IPCC Special Report on Global Warming of 1.5 °C (SR15). The CO 2 emission levels are adjusted so that the pathways all have the same total CO 2 equivalent emissions for a given emissions metric but have different proportions of short-lived and long-lived pollutants. We show that this difference affects projections by up to 0.17 °C when GWP 100 is used. Options of reducing this ambiguity include using a different emissions metric or adding supplementary information in NDCs about the emissions levels of individual GHGs. We suggest the latter on the grounds of simplicity and because it does not require agreement on the use of a different emissions metric.