Fairly sharing 1.5: national fair shares of a 1.5 °C-compliant global mitigation effort

  • Christian HolzEmail author
  • Sivan Kartha
  • Tom Athanasiou
Original Paper


The problem of fairly distributing the global mitigation effort is particularly important for the 1.5 °C temperature limitation objective, due to its rapidly depleting global carbon budget. Here, we present methodology and results of the first study examining national mitigation pledges presented at the 2015 Paris climate summit, relative to equity benchmarks and 1.5 °C-compliant global mitigation. Uniquely, pertinent ethical choices were made via deliberative processes of civil society organizations, resulting in an agreed range of effort-sharing parameters. Based on this, we quantified each country’s range of fair shares of 1.5 °C-compliant mitigation, using the Climate Equity Reference Project’s allocation framework. Contrasting this with national 2025/2030 mitigation pledges reveals a large global mitigation gap, within which wealthier countries’ mitigation pledges fall far short, while poorer countries’ pledges, collectively, meet their fair share. We also present results for individual countries (e.g. China exceeding; India meeting; EU, USA, Japan, and Brazil falling short). We outline ethical considerations and choices arising when deliberating fair effort sharing and discuss the importance of separating this choice making from the scholarly work of quantitative “equity modelling” itself. Second, we elaborate our approach for quantifying countries’ fair shares of a global mitigation effort, the Climate Equity Reference Framework. Third, we present and discuss the results of this analysis with emphasis on the role of mitigation support. In concluding, we identify twofold obligations for all countries in a justice-centred implementation of 1.5 °C-compliant mitigation: (1) unsupported domestic reductions and (2) engagement in deep international mitigation cooperation, through provision of international financial and other support, or through undertaking additional supported mitigation activities. Consequently, an equitable pathway to 1.5 °C can only be imagined with such large-scale international cooperation and support; otherwise, 1.5 °C-compliant mitigation will remain out of reach, impose undue suffering on the world’s poorest, or both.


Effort-sharing Fair shares Climate justice Equity Mitigation NDCs UNFCCC 



Climate Action Tracker


Common but differentiated responsibilities and respective capabilities


Climate Equity Reference Project


Climate Equity Reference Framework


Conference of the Parties (to the UNFCCC)


Civil society organization(s)


European Union


European Union, in its 15-member-state configuration from 1995 to 2004


European Union, in its 28-member-state configuration since 2013


Greenhouse Development Rights


Gross domestic product


Global warming potential


Intended nationally determined contribution(s)


Intergovernmental Panel on Climate Change


Nationally determined contribution(s)


Non-governmental organization


Organisation for Economic Co-operation and Development


Organization of the Petroleum Exporting Countries


Purchasing power parity




United Nations Framework Convention on Climate Change


United States of America



The authors are grateful for the immensely fruitful discussions among the members of the Civil Society Equity Review coalition that are too many to name here. The Climate Equity Reference Project’s work on NDC review has been supported by grants from the Rockefeller Brothers’ Fund, Christian Aid, WWF International, and Oxfam International. The authors also gratefully acknowledge the comments received from an anonymous reviewer and the editors of this special issue. Any remaining errors of fact and opinion are, of course, ours alone.

Supplementary material

10784_2017_9371_MOESM1_ESM.pdf (357 kb)
Supplementary material 1 (PDF 356 kb)
10784_2017_9371_MOESM2_ESM.xlsx (130 kb)
Supplementary material 2 (XLSX 129 kb)


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Copyright information

© Springer Science+Business Media B.V. 2017

Authors and Affiliations

  1. 1.Climate Equity Reference ProjectBerkeleyUSA
  2. 2.Stockholm Environment InstituteSomervilleUSA
  3. 3.EcoEquityBerkeleyUSA

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