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


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.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2


  1. 1.

    At the nineteenth Conference of the Parties of the UNFCCC, COP19, these unilaterally determined pledges were first called “intended nationally determined contributions”, or INDCs (UNFCCC 2013, 1/CP.19, para 2). In the context of the Paris Agreement (UNFCCC 2015a), the “intended” was dropped for countries that have ratified the Agreement, resulting in NDCs. Currently, the majority of UNFCCC Parties have ratified the Agreement, causing NDCs to dominate over INDCs. Thus, even though this article chiefly reports on a review exercise of the INDCs submitted prior to the Paris Agreement’s adoption, we will use the term “NDC” (or “pledge”) in this article regardless of its legal status as NDC or INDC, except when to specifically refer to the original submissions of the INDCs.

  2. 2.

    The analysis and exposition of GDRs was typically presented in terms of one particular choice of equity settings, which were made a priori by the authors and then explained and justified based on a particular set of ethical arguments and value judgements. CERF is a generalization in the sense that it is based on the same framework with the same structure as GDRs, but allows for a limitless range of user-specified choices of all the available equity variables. In other words, the difference essentially is one of its flexibility, its user interface, and its pedagogic purpose. It is used as an analytical and educational platform, designed to clarify the different moral choices to be made and to calculate their impact on national fair share results. A detailed exposition of these impacts has been done elsewhere (Athanasiou et al. 2014).

  3. 3.

    In the most general terms, “burden-sharing” approaches can be categorized into two broad classes: “resource-sharing” and “effort-sharing” approaches, where the former “are aimed at applying ethical principles to establish a basis for sharing the agreed global ‘carbon budget’”, while the latter “are aimed at sharing the costs of the global climate response” (IPCC 2014, p. 319).

  4. 4.

    Even though countries are the typical unit of analysis, its generalizability allows the CERF to be applied to different levels of analysis, such as sub-national entities (for example, Canadian provinces, Holz 2014) or socio-economic strata. For simplicity, when describing the general framework and methodologies we will refer to “countries” as this is the unit of analysis here.

  5. 5.

    This analysis uses a custom disaggregation of the “CAT 1.5 °C Median Pathway”. See Supplementary Text 1 for a pathway description and reference to the pathway data.

  6. 6.

    This quantification is done with the online “Climate Equity Reference Calculator” (Kemp-Benedict et al. 2017), available at https://calculator.climateequityreference.org.

  7. 7.

    In the practical implementation of the Climate Equity Reference Calculator (Kemp-Benedict et al. 2017), this is done by estimating income and emission distributions across a population and applying the progressivity parameters (e.g. development thresholds) to that distribution rather than to individual-level data, which is not typically available (see Kemp-Benedict et al. 2013 for technical details). Conceptually, however, responsibility and capacity are understood in individual terms and thus individual fair shares could be calculated. See, for example, the implied “tax tables” for individuals of certain income levels implied by the approach in earlier work using the GDRs framework (Kartha et al. 2008, p. 27).

  8. 8.

    The initial set of organizations that spearheaded the review is shown on the inside cover page of its report (CSO Review 2015); a full list in its appendix.

  9. 9.

    Clearly, the level where to best set a development threshold is a matter for debate. We have consistently (e.g. Baer et al. 2008) taken the position that it ought to be at least slightly higher than a global poverty line, which is about $16 per day (PPP adjusted). This figure represents the income levels where people begin to overcome the typical manifestations of poverty (low educational attainment, high relative food expenditures, malnutrition, high infant mortality), according to empirical analysis (Pritchett 2003, 2006). According to Pritchett, “if the poverty line were defined as the level of income at which people typically achieve acceptable levels of the Millennium Development Goal indicators (such as universal primary school completion), it would be set at about [$16] a day” (Pritchett 2006, p. 13) which “is justifiable, more consistent with international fairness, and is a better foundation for […] poverty reduction” (Pritchett 2003, p. 3).

  10. 10.

    It is important to recall, and the IPCC authors themselves recognized this, that this categorization is incomplete and by no means an authoritative, ethically robust catalogue of equity approaches. This is because it was based on an opportunistic ensemble of burden-sharing approaches previously quantified in the literature that were selected according to certain modelling criteria and “only covers a small proportion of the possible allocation approaches” (Höhne et al. 2014, p. 122). Note also that the IPCC, in that same chapter and elsewhere, explicitly acknowledges the ethical importance of other approaches, principles, and indices that are examined elsewhere in the literature, including “the relative moral relevance of consumption-based emissions as opposed to production-based emissions, survival emissions as opposed to luxury emissions, progressive as opposed to regressive allocation of mitigation costs, prioritarianism as opposed to egalitarianism, and—not least—the right to development and the critical ethical importance of the eradication of poverty” (Kartha et al. 2017).

  11. 11.

    All emissions or mitigation figures in this article include emissions and removals from land use, land use change, and forestry, as well as emissions of non-CO2 greenhouse gases.

  12. 12.

    Due to the large inequality among EU countries (especially when comparing “new” member states and the EU15), the same can be observed for the EU28, albeit much less pronounced. When investigating the EU15 separately, this effect disappears.

  13. 13.

    Some of the difference between these studies and ours can be explained by different treatment of emissions from international aviation and shipping (which only UNEP (2016) and UNFCCC (2016) include), emissions from land use, land use change and forestry (which Robiou du Pont et al. (2016) exclude), and the use of different metrics for calculating the global warming potential (GWP) of non-CO2 greenhouse gases (UNEP (2016) and UNFCCC (2016) use GWP values from the IPCC’s Fourth Assessment Report, Robiou du Pont et al. (2016), and this study utilize Second Assessment Report values). Other gap estimates (for example, UNEP 2015; UNFCCC 2015c) only assess mitigation shortfalls relative to 2 °C-compliant pathways and are therefore not suited for comparison here.

  14. 14.

    While not ideal, these labels have been chosen over the more common “developed” and “developing” in particular to indicate that these groups, and their membership, are both conceptually and in practical terms distinct from the use of developed/developing country in the UNFCCC and the Paris Agreement and do not match the Annexes of the 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


  1. Anderson, K. (2015). Duality in climate science. Nature Geoscience. doi:10.1038/ngeo2559.

    Google Scholar 

  2. Athanasiou, T., Baer, P., & Kartha, S. (2006). Greenhouse development rights: An approach to the global climate regime that takes climate protection seriously while also preserving the right to human development. Berkeley; London: EcoEquity; Christian Aid. http://gdrights.org/wp-content/uploads/2009/03/gdrs_nairobi.pdf.

  3. Athanasiou, T., Kartha, S., & Baer, P. (2014). National fair shares: The mitigation gapDomestic action and international support. Berkeley and Somerville: EcoEquity and Stockholm Environment Institute. http://www.ecoequity.org/wp-content/uploads/2014/11/National-fair-shares.pdf.

  4. Baer, P., Athanasiou, T., Kartha, S., & Kemp-Benedict, E. (2008). The greenhouse development rights framework. The right to development in a climate constrained world, second edition. Berlin: Heinrich Böll Foundation, Christian Aid, EcoEquity and the Stockholm Environment Institute. http://www.ecoequity.org/docs/TheGDRsFramework.pdf.

  5. Caney, S. (2009). Justice and the distribution of greenhouse gas emissions. Journal of Global Ethics. doi:10.1080/17449620903110300.

    Google Scholar 

  6. CAT. (2016). Global temperatures. Climate Action Tracker. http://climateactiontracker.org/global.html.

  7. Chung, R. K. (2007). A CER discounting scheme could save climate change regime after 2012. Climate Policy. doi:10.1080/14693062.2007.9685647.

    Google Scholar 

  8. CSO Review. (2015). Fair shares: A civil society equity review of INDCs. Manilla, London, Cape Town, Washington, et al.: CSO Equity Review Coalition. civilsocietyreview.org/report.

  9. CSO Review. (2016). Setting the path towards 1.5 °C: A civil society equity review of pre-2020 ambition. Manilla, London, Cape Town, Washington, et al.: CSO Equity Review Coalition. civilsocietyreview.org/report2016.

  10. Faran, T. S., & Olsson, L. (2017). Geoengineering of climate change: Neither ethical, nor economical. Risk-reward nexus analysis of geoengineering. International environmental agreements: Politics, law and economics, special issue: Achieving 1.5 °C and climate justice.

  11. Gupta, J., & Arts, K. (2017). Achieving the 1.5 °C objective: Just implementation through a right to (sustainable) development approach. International environmental agreements: Politics, law and economics, special issue: Achieving 1.5 °C and climate justice.

  12. Höhne, N., den Elzen, M., & Escalante, D. (2014). Regional GHG reduction targets based on effort sharing: A comparison of studies. Climate Policy. doi:10.1080/14693062.2014.849452.

    Google Scholar 

  13. Höhne, N., den Elzen, M., & Weiss, M. (2006). Common but differentiated convergence (CDC): A new conceptual approach to long-term climate policy. Climate Policy, 6(2), 181–199. doi:10.1080/14693062.2006.9685594.

    Article  Google Scholar 

  14. Holz, C. (2014). How can Canada’s contribution to climate action be shared fairly among provinces? Presented at the International Political Economy Network and Centre for International Policy Studies Speaker Series, Ottawa, September 13. http://cips.uottawa.ca/event/equity-in-the-greenhouse-fairly-sharing-canadas-climate-change-mitigation-effort-among-provinces-and-territories.

  15. Holz, C., Athanasiou, T., & Kartha, S. (2017). Estimates of emissions levels associated with the intended nationally determined contributions (INDCs). Harvard Dataverse. doi:10.7910/DVN/RIBJXF.

    Google Scholar 

  16. IPCC. (2013). Climate change 2013: The physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change. In T. F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, et al. (Eds.). Cambridge, New York: Cambridge University Press. www.climatechange2013.org/images/report/WG1AR5_SPM_FINAL.pdf.

  17. IPCC. (2014). Climate change 2014: Mitigation of climate change. Contribution of working group III to the fifth assessment report of the intergovernmental panel on climate change. Cambridge: Cambridge University Press. http://mitigation2014.org/report/final-draft.

  18. Kartha, S., Athanasiou, T., & Baer, P. (2012). The north–south divide, equity and development—The need for trust-building for emergency mobilisation. In N. Hällström (Ed.), What next volume III: Climate, development and equity (pp. 47–71). Uppsala: The Dag Hammarskjöld Foundation. http://www.dhf.uu.se/publications/development-dialogue/dd61/.

  19. Kartha, S., Athanasiou, T., Baer, P., & Kemp-Benedict, E. (2008). A call for leadership. A greenhouse development rights analysis of the EU’s proposed 2020 targets. Somerville and Berkeley: EcoEquity and Stockholm Environment Institute. http://gdrights.org/wp-content/uploads/2009/10/a_call_for_leadership.pdf.

  20. Kartha, S., Athanasiou, T., Caney, S., Cripps, E., Dooley, K., Dubash, N. K., et al. (2017). Response to Robiou du Pont et al on climate equity. Nature Climate Change . https://ssrn.com/abstract=3022357.

  21. Kemp-Benedict, E., Athanasiou, T., Baer, P., & Kartha, S. (2013). Calculations for the greenhouse development rights calculator. Stockholm Environmental Institute; EcoEquity.

  22. Kemp-Benedict, E., Holz, C., Baer, P., Athanaisou, T., & Kartha, S. (2017). The climate equity reference calculator. Berkeley and Somerville: Climate Equity Reference Project (EcoEquity and Stockholm Environment Institute). https://calculator.climateequityreference.org.

  23. Lahn, B. (2017). In the light of equity and science: Scientific expertise and climate justice after Paris. International environmental agreements: Politics, law and economics, special issue: Achieving 1.5 °C and climate justice.

  24. Meinshausen, M., & Alexander, R. (2016). NDC & INDC factsheets. Version November 4, 2016, Metric GWP SAR. Melbourne: Australian-German Climate and Energy College. http://climate-energy-college.org/ndc-indc-factsheets.

  25. Meyer, A. (2004). Briefing: Contraction and convergence. Proceedings of the Institution of Civil EngineersEngineering Sustainability, 157(4). https://doi.org/10.1680/ensu.2004.157.4.189.

  26. Pritchett, L. (2003). Who is not poor? Proposing a higher international standard for poverty (No. CBD Working Paper Number 33). Center for global development. https://www.cgdev.org/publication/who-not-poor-proposing-higher-international-standard-poverty-working-paper-33.

  27. Pritchett, L. (2006). Who is not poor? Dreaming of a world truly free of poverty. The World Bank Research Observer. doi:10.1093/wbro/lkj002.

    Google Scholar 

  28. Rao, N. D. (2014). International and intranational equity in sharing climate change mitigation burdens. International Environmental Agreements: Politics, Law and Economics. doi:10.1007/s10784-013-9212-7.

    Google Scholar 

  29. Robiou du Pont, Y., Jeffery, M. L., Gütschow, J., Rogelj, J., Christoff, P., & Meinshausen, M. (2016). Equitable mitigation to achieve the paris agreement goals. Nature Climate Change. doi:10.1038/nclimate3186.

    Google Scholar 

  30. Rogelj, J., Luderer, G., Pietzcker, R. C., Kriegler, E., Schaeffer, M., Krey, V., et al. (2015). Energy system transformations for limiting end-of-century warming to below 1.5 °C. Nature Climate Change. doi:10.1038/nclimate2572.

    Google Scholar 

  31. Shue, H. (2015). Historical responsibility, harm prohibition, and preservation requirement: Core practical convergence on climate change. Moral Philosophy and Politics. doi:10.1515/mopp-2013-0009.

    Google Scholar 

  32. Shue, H. (2017). Climate dreaming: Negative emissions, risk transfer, and irreversibility. Journal of Human Rights and Environment. doi:10.2139/ssrn.2940987.

    Google Scholar 

  33. Stern, T. (2013). Chapter 13: Environment and other transnational scientific issues. In Digest of United States Practice in International Law (Vol. 2013, pp. 383–387). Washington, D.C.: Office of the Legal Adviser, United States Department of State. https://www.state.gov/s/l/2013/index.htm.

  34. Swingle, C. (2016). Ambition and fairness: Understanding equity through intended nationally determined contributions (Senior Capstone Project for Environmental Studies). Williams College, Williamstown.

  35. UNEP. (2015). The emissions gap report 2015. Nairobi: United Nations Environment Programme. http://uneplive.unep.org/media/docs/theme/13/EGR_2015_Technical_Report_final_version.pdf.

  36. UNEP. (2016). The emissions gap report 2016. A UNEP synthesis report. Nairobi: United Nations Environment Programme. http://uneplive.unep.org/media/docs/theme/13/Emissions_Gap_Report_2016.pdf.

  37. UNFCCC. (1992). United nations framework convention on climate change. Bonn: UNFCCC. http://unfccc.int/resource/docs/convkp/conveng.pdf.

  38. UNFCCC. (2013). Report of the conference of the parties on its nineteenth session, held in Warsaw from 11 to 23 November 2013. Geneva: United Nations Office. http://unfccc.int/resource/docs/2013/cop19/eng/10a01.pdf.

  39. UNFCCC. (2015a). Paris agreement. Geneva: United Nations Office. http://unfccc.int/files/meetings/paris_nov_2015/application/pdf/paris_agreement_english_.pdf.

  40. UNFCCC. (2015b). Report of the conference of the parties on its twentieth session, held in Lima from 1 to 14 December 2014. Geneva: United Nations Office. http://unfccc.int/resource/docs/2014/cop20/eng/10a01.pdf.

  41. UNFCCC. (2015c). Synthesis report on the aggregate effect of the intended nationally determined contributions. Bonn: UNFCCC. http://unfccc.int/resource/docs/2015/cop21/eng/07.pdf.

  42. UNFCCC. (2016). Aggregate effect of the intended nationally determined contributions: An update. Synthesis report by the secretariat. Bonn: UNFCCC. http://unfccc.int/resource/docs/2016/cop22/eng/02.pdf.

  43. USA. (2015). Intended nationally determined contribution. Washington, DC: U.S. Department of State. http://www4.unfccc.int/Submissions/INDC/Published%20Documents/United%20States%20of%20America/1/U.S.%20Cover%20Note%20INDC%20and%20Accompanying%20Information.pdf.

  44. Winkler, H., Baumert, K., Blanchard, O., Burch, S., & Robinson, J. (2007). What factors influence mitigative capacity? Energy Policy. doi:10.1016/j.enpol.2006.01.009.

    Google Scholar 

  45. Winkler, H., Höhne, N., Cunliffe, G., Kuramochi, T., April, A., & de Villafrance Casas, M. J. (2017). Countries start to explain how their climate contributions are fair—More rigour needed. International environmental agreements: Politics, law and economics, special issue: Achieving 1.5 °C and climate justice. (forthcoming).

  46. Winkler, H., & Rajamani, L. (2014). CBDR&RC in a regime applicable to all. Climate Policy. doi:10.1080/14693062.2013.791184.

    Google Scholar 

Download references


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.

Author information



Corresponding author

Correspondence to Christian Holz.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary material 1 (PDF 356 kb)

Supplementary material 2 (XLSX 129 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Holz, C., Kartha, S. & Athanasiou, T. Fairly sharing 1.5: national fair shares of a 1.5 °C-compliant global mitigation effort. Int Environ Agreements 18, 117–134 (2018). https://doi.org/10.1007/s10784-017-9371-z

Download citation


  • Effort-sharing
  • Fair shares
  • Climate justice
  • Equity
  • Mitigation
  • NDCs