National post-2020 greenhouse gas targets and diversity-aware leadership

Authors: Malte Meinshausen, Louise Jeffery, Johannes Guetschow, Yann Robiou du Pont, Joeri Rogelj, Michiel Schaeffer, Niklas Höhne, Michel den Elzen, Sebastian Oberthür, and Nicolai Meinshausen

Abstract: Achieving the collective goal of limiting warming to below 2C or 1.5C compared to pre-industrial levels requires a transition towards a fully decarbonized world. Annual greenhouse gas emissions on such a path in 2025 or 2030 can be allocated to individual countries using a variety of allocation schemes. We reanalyse the IPCC literature allocation database and provide country-level details for three approaches. At this stage, however, it seems utopian to assume that the international community will agree on a single allocation scheme. Here, we investigate an approach that involves a major-economy country taking the lead. In a bottom-up manner, other countries then determine what they consider a fair comparable target, for example, either a ‘per-capita convergence’ or ‘equal cumulative per-capita’ approach. For example, we find that a 2030 target of 67% below 1990 for the EU28, a 2025 target of 54% below 2005 for the USA or a 2030 target of 32% below 2010 for China could secure a likely chance of meeting the 2C target in our illustrative default case. Comparing those targets to post-2020 mitigation targets reveals a large gap. No major emitter can at present claim to show the necessary leadership in the concerted effort of avoiding warming of 2C in a diverse global context.

Citation: Meinshausen, M., L. Jeffery, J. Guetschow, Y. Robiou du Pont, J. Rogelj, M. Schaeffer, N. Hohne, M. den Elzen, S. Oberthur and N. Meinshausen (2015). "National post-2020 greenhouse gas targets and diversity-aware leadership." Nature Clim. Change advance online publication.

Link to main article: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2826.html

Supplementary available here: http://www.nature.com/nclimate/journal/vaop/ncurrent/extref/nclimate2826-s1.pdf

Interactive data appendix: www.mitigation-contributions.org

Slidestack with slideshow: http://www.climate-energy-college.net/files/site1/docs/11/SlideStack_Post-2020GHGreductions.ppt

Briefing paper on main findings: http://sustainable.unimelb.edu.au/climate-leadership