The science

About the Paris Equity Check assessment

Several websites provide equity assessments of the mitigation commitments or policies of major emitting countries. The assessment of www.Paris-equity-check.org has specific characteristics:

  • Multi-dimensional. The website shows equitable national contributions according to each of the five categories of equity introduced by the IPCC. Each country's Nationally Determined Contribution (NDC) - a climate action plan - can be compared with each of the five equity categories. The equity assessment can also be compared with countries’ statements on the fairness of their contribution (available at: http://cait.wri.org/indc/).

  • Scientific and peer-reviewed. This website is the only multi-dimensional assessment whose methodology and results are completely published and peer-reviewed. The methods, available in an open access journal, are transparent and the results are reproducible using the equity formula.

  • Paris Agreement consistent. The national emissions allocations are specifically consistent with the Paris Agreement goals of: net-zero emissions before 2100, peaking of global emissions as soon as possible, and a warming of either 1.5 °C or well below 2 °C.

  • Cost-optimal. The emissions of all countries add up to cost-optimal global mitigation scenarios selected from the IPCC database or a peer-reviewed study1 that match the Paris Agreement goals.

  • Comprehensive. The results are available for 171 parties(1) to the UNFCCC.

  • Long-term assessment. Countries are allocated equitable emissions scenarios that stretch until 2100. Equitable mitigation targets are therefore available for any year until 2100.

  • Multi-gas assessment. Burden sharing is usually represented by CO2 allocations (often ‘carbon budgets’), while other greenhouse gases (GHG) have a significant impact on global warming. This website presents allocations of GHG emissions (see box below).

(1) The derivation of equitable emissions allocation requires data projection of GDP, business-as-usual emissions. The PRIMAP database does not contain such projections for all countries due to a lack of available data. More details are available in the Methods section of the publication.

Emissions scenarios vs. carbon budgets

Carbon (CO2) budgets are often associated with climate objectives. Because CO2 has a long lifetime in the atmosphere, the temperature at the end of the century depends on the cumulative CO2 emissions rather than on the timing of those CO2 emissions. A linear relationship links the cumulative CO2 emissions to the maximal temperature over the century2, under assumptions regarding non-CO2 gases.

Using carbon budgets allows us to understand how national budgets change according to temperature goals. However, using carbon budgets do not provide information on the least-cost measures and their timing to achieve the CO2 mitigation. By contrast, greenhouse-gases (GHG) emissions scenarios from Integrated Assessment Models are associated with specific policies and technology deployment, which minimize the emissions mitigation costs. An additional advantage of using multi-gas emissions scenarios to derive national allocations is that this allows us to assess countries' mitigation measures on not just CO2, but all of the main greenhouse-gases (as defined in the Kyoto-Protocol: methane, nitrous oxide…).


Temperature goals in the Paris Agreement

The choice of a limit to global warming itself represents a choice on equity. Indeed, the climate impacts are unevenly distributed around the globe and affect vulnerable countries the most. A 2 °C warming represents major risks, sometimes existential, for many countries3. As a result, in 2008 a group of 101 countries called for a 1.5 °C warming limit.

In 2013, the UNFCCC initiated a ‘Structured Expert Dialogue’ with over 70 experts to assess the adequacy of the long-term global goal with its ultimate objective. The report on this two-year long review highlighted that:

“The ‘guardrail’ concept, in which up to 2 °C of warming is considered safe, is inadequate and would therefore be better seen as an upper limit, a defence line that needs to be stringently defended, while less warming would be preferable.”

and

“While science on the 1.5 °C warming limit is less robust, efforts should be made to push the defence line as low as possible.”

As a consequence, the Paris Agreement states an aim of:

Holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change”

A more detailed analyses of the Paris Agreement temperature goal is available here.


Methodology

INDC assessment

In 1992, under the UNFCCC treaty, countries agreed to pursue mitigation efforts following to their “Common but Differentiated Responsibilities and Respective Capabilities” (CBDR-RC). With the Paris Agreement, all ratifying Parties must communicate successive Nationally Determined Contributions (NDCs) that represent a progression in ambition and reflect the “highest possible ambition” with respect to their CBDR-RC. In particular, the Paris Agreement invites developed countries, without naming them4, to take the lead in mitigating economy-wide emissions and in mobilizing climate finance. Historically, few countries have indicated which equity principle5–7 or formula8 they used to derive their mitigation contributions and justify the consistency of these contributions with the principle of CBDR-RC. Instead, many countries simply declared their INDCs to be “fair and ambitious”, either explicitly (e.g. India and the USA9, see national statements on this website) or implicitly by the lack of further explanation.

The quantitative assessment of the (Intended) Nationally Determined Contributions – or (I)NDCs – used here is detailed in ‘Factsheets’ for all countries under high or low ambition estimates. The current national commitments for 2030 add up to a global level of 52.5 GtCO2eq (the average of the ‘high-ambition’ and ‘low-ambition’ estimates10 49.4 GtCO2eq and 55.6 GtCO2eq respectively).

What is an (I)NDC?

(I)NDCs – (Intended) Nationally Determined Contributions - are climate action plans that were submitted to the UNFCCC during the lead-up to the Paris Agreement in 2015.

All climate action plans are ‘nationally determined’ and so take many different forms. Most contain a plan to limit the growth of GHG emissions, many also contain adaptation plans, an outline of national circumstances, and a description of the funds needed to carry out their plans.

When countries ratify the Paris Agreement, they have to submit an NDC. Most ratifying countries’ NDCs are the same as their INDC. The UNFCCC website hosts all of the INDCs and NDCs submitted so far.

Global cost-optimal emissions scenarios

Unlike most earlier studies, the method used here ensures that emissions are allocated to countries such that the global aggregate of these national allocations is compatible with the global cost-optimal emissions scenario.

The global cost-optimal emissions scenarios used here were specifically selected to match the goals of the Paris Agreement, namely: net-zero emissions before 2100, peaking of global emissions as soon as possible, and maximum warming of either 1.5 °C or well below 2 °C.

The selected global emissions scenarios (from the IPCC database and a peer-reviewed study1), include land-use and international aviation and shipping emissions, and have the following features:

  • global emissions peaking by 2020,

  • global net-zero emission by 2100,

  • at least a likely (>66%) chance of limiting global warming to below 2 °C for the rest the century,

  • a subset of 1.5 °C scenarios with a more likely than not (>50%) chance of returning to below 1.5 °C of warming in 2100.

In 2030, the average emissions level of the selected 2 °C scenarios is 39.7 GtCO2eq, which is almost equal to the indicative goal of 40 GtCO2eq of the Paris Decision, and the 1.5 °C scenarios have average 2030 emissions of 32.6 GtCO2eq. Following 2 °C scenarios results in net-zero emissions as early as 2080, while 1.5 °C scenarios become negative between 2059 and 2087.

The maximum annual mitigation rates of the 2 °C scenarios over the 21st century is 2.1%/y in 2025 (and 1.6%/y on average over the 2030-2050 period). The annual mitigation rate of the 1.5 °C scenarios reaches 2.3%/y in 2039 (and 2.2%/y on average over the period 2030-2050).

Range and average of global cost-optimal emissions scenarios consistent with the Paris Agreement goals.

Range and average of global cost-optimal emissions scenarios, including land-use and bunker emissions, consistent with the Paris Agreement goals.

Equity allocation

National emissions allocations are quantified following the five equity categories presented in the IPCC-AR5 WGIII Ch. 6 (Table 6.5). The methodology is detailed in this study, and the formula and parameterization available here. Each of these allocation approaches allocates the emissions of the cost-optimal scenarios presented in the “Temperature goal” section, but exclude emissions from the land-use sector and from international aviation and shipping. The national equitable emissions allocations presented in this website can be met with a combination of domestic mitigation, internationally traded emissions mitigation11 and support towards global mitigation.

Allocation name

Code

IPCC category

Allocation characteristics

Capability

CAP

Capability

Countries with high GDP per capita have low emissions allocations.

Equal cumulative per capita

CPC

Equal cumulative per capita

Populations with high historical emissions have low emissions allocations.

This approach allocates to each country total cumulative emissions proportional to its cumulative population over the 1990-2100 period.

Greenhouse Development Rights

GDR

Responsibility-capability-need

Countries with high GDP per capita and high historical emissions per capita have low emissions allocation.

This approach preserves a ‘right to development’ through the allocation of mitigation requirements12–14.

Equal per capita

EPC

Equality

Convergence towards equal annual emissions per person in 2040.

Constant emissions ratio

CER

Staged approaches

Maintains current emissions ratios, preserves status quo.

This approach, often referred to as ‘grandfathering’, is generally not considered as an equitable option in climate justice15 and is not supported as such by any Party.


References

  1. Rogelj, J. et al. Energy system transformations for limiting end-of-century warming to below 1.5 °C. Nat. Clim. Chang. 5, 519–527 (2015).

  2. IPCC. in Climate Change 2014, Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (ed. Edenhofer O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Z. and J. C. M.) 1–33 (Cambridge University Press, 2014).

  3. Schleussner, C.-F. et al. Differential climate impacts for policy-relevant limits to global warming: the case of 1.5 °C and 2 °C. Earth Syst. Dyn. Discuss. 6, 2447–2505 (2016).

  4. Voigt, C. & Ferreira, F. Differentiation in the Paris Agreement. Clim. Law 6, 58–74 (2016).

  5. Commission of the European Communities. Impact Assessment: Document accompanying the Package of Implementation measures for the EU’s objectives on climate change and renewable energy for 2020 Proposals. (2008).

  6. Japan. Submission by Japan - Information, views and proposals on matters related to the work of Ad Hoc Working Group on the Durban Platform for Enhanced Action (ADP) Workstream 1. (2014).

  7. Nepal on Behalf of the Least Developed Countries Group. Submission by the Nepal on behalf of the Least Developed Countries Group : Views and proposals on the work of the Ad Hoc Working Group on the Durban Platform for Enhanced Action ( ADP ). (2014).

  8. BASIC experts. Equitable access to sustainable development: Contribution to the body of scientific knowledge. BASIC expert group: Beijing, Brasilia, Cape Town and Mumbai (2011).

  9. UNFCCC. Submitted INDCs. (2016). Available at: http://www4.unfccc.int/submissions/indc/. (Accessed: 5th February 2016)

  10. Meinshausen, M. Climate College - INDC Factsheets. (2015). Available at: http://climatecollege.unimelb.edu.au/indc-factsheets/.

  11. UNFCCC. Paris Agreement. (2015).

  12. Baer, P., Fieldman, G., Athanasiou, T. & Kartha, S. Greenhouse Development Rights: towards an equitable framework for global climate policy. Cambridge Rev. Int. Aff. 21, 649–669 (2008).

  13. Kemp-Benedict, E. Calculations for the Greenhouse Development Rights Calculator. (2010).

  14. Meinshausen, M. et al. National post-2020 greenhouse gas targets and diversity-aware leadership. Nat. Clim. Chang. 1–10 (2015). doi:10.1038/nclimate2826

  15. Caney, S. Justice and the distribution of greenhouse gas emissions. J. Glob. Ethics 5, 125–146 (2009).