About the Climate Equity Reference Project

The Climate Equity Reference Project (CERP) is a long-term initiative designed to provide scholarship, tools, and analysis to advance global climate equity – as a value in itself and as a realist path towards an ambitious global climate regime. The CERP is strongly rooted in current climate science, in particular the IPCC’s estimates of the remaining global carbon budget. It is also consistent with the UN Framework Convention’s core equity principles, which can be concisely stated as “a precautionary approach to adequacy,” “common but differentiated responsibilities and respective capabilities,” and “equitable access to sustainable development.”

This site offers explanations of the CERP effort-sharing framework, as well as an online Climate Equity Reference Calculator that allows users to interactively explore user-defined implementations of that framework. Importantly, it also offers a set of INDC assessments that is based upon the outputs of that calculator. While these assessments are made relative to an indicative “equity band” that is bounded by two pre-defined “equity settings” (“High Equity” and “Low Equity”), the online Calculator allows, and indeed encourages, users to choose their own preferred equity settings.

A few key points

The CERP approach is designed to be general, to encompass a wide set of equity approaches, to express these approaches by way of straightforward and objective indicators, and to clearly present their implications with respect to national fair shares of a common global effort. At the same time, it is precise enough to quantitatively evaluate and compare national contributions to the common effort, as they are being tabled in the international climate negotiations.

In all this, there are a small number of key points to keep in mind:

  • The CERP approach is a dynamic one. For each nation in each year, indicators of and , together with a variety of macro-economic data that together define national development need (estimated by way of a ) are used to calculate a , or RCI. The exact definitions of responsibility, capacity, and development need, and the relative weighting given to responsibility and capacity, are chosen by the user.
  • The national RCI is then used to determine the national of the , which is also based on a global “no policy baseline” and on the user’s choice of a . The following figure illustrates the method here, by showing a global mitigation requirement that is partitioned into national fair shares, which are assigned to individual countries on the basis of their dynamically shifting responsibility and capacity.
    Global-Mitigation-Wedge-Strong-2C RCI-Fair-Share-Wedges-Strong-2C
    Globally required mitigation (blue area) divided among countries in proportion to their share of global responsibility and capacity.  (The example here, and it is only an example, features the “Strong 2°C” global mitigation pathway and the “medium equity” settings.  See the National Fair Shares report for an overview set of illustrative cases.)
  • The Responsibility and Capacity Index can also quite properly be used to estimate national fair shares in a global adaptation effort.  Not that it can help us to estimate the global , or the adaptation need of any given country, but it does offer a way to think about national fair shares of any monetized, global, climate-related effort.  (Global adaptation need is properly estimated as a function of projected temperature change and national vulnerability.  At the moment, in the Calculator, all we offer is a user-defined parameter that is specified as a percentage of projected Gross World Product.)
  • Critically, national fair shares of the global mitigation requirement are not seen in domestic terms. The CERP views climate as a global commons problem that can only be solved within a high-cooperation international regime. Such a regime can only be established if each Party sees others to be doing their fair shares in the face of the common challenge.  In practice, of course, each country will decide, on the basis of its own specific considerations (e.g. it’s own view of costs, co-benefits and political-economic tradeoffs) what fraction of its fair share of the global mitigation effort it will attempt domestically, and what fraction it will make off shore” by supporting mitigation action in other countries.

Key Links

The Climate Equity Reference Calculator

The Climate Equity Reference Calculator is a interactive online equity reference tool that systematically applies CERP’s Effort-sharing Approach, with the goal of allowing users to quantitatively examine the problem of national fair shares in a global effort to rapidly reduce greenhouse gas emissions. This approach can be applied using a range of mitigation pathways, “Equity Settings,” and other assumptions. Whichever are chosen, they are applied to all countries, in a dynamic fashion that reflects the changing global economy.

National Fair Shares: The Mitigation Gap – Domestic Actions & International Support

The National Fair Shares report is a systematic attempt to apply CERP’s Effort-sharing Approach to a set set of twelve representative countries and a  selected set of illustrative “cases.”  These cases are bounded by a “high equity” case and a “low equity” case, which together define an illustrative equity band.

Assessment of National INDCs

The Climate Equity Reference Framework is designed to support the meaningful analysis of national climate action pledges, relative to the global challenge and relative to other national pledges.  Our initial assessment of the national INDCs illustrates some of the possibilities of applying equity reference frameworks to national pledges.  In this assessment, importantly, the equity and ambition of individual INDCs are examined within the CERP’s Resource-sharing Approach, as well as within its Effort-sharing Approach.

Historical Note

This project is an evolution beyond our earlier Greenhouse Development Rights project. It provides a more general approach to a dynamic equity reference framework, and is focused on highlighting those results and conclusions that are common across a wide range of perspectives.

In the calculations here, responsibility – contribution to the climate problem – is defined as the sum of all emissions corresponding to consumption above the user-specified development threshold (as is the case with capability).  Emissions corresponding to consumption below that threshold are not included in the calculation of responsibility, as they are exempted on the grounds of, say, being associated with basic or survival consumption.

Responsibility is measured cumulatively since some user-specified start date. (To the extent that emissions before the start date contributed to current capability, they are accounted for implicitly in the capability measure.) In calculating national fair shares, responsibility and capability (a simple average, in the default case, though the weighting can be changed) are combined to compute a Responsibility and Capability Index.

This calculator defines capability in income terms. It allows the user use a progressive definition, in that it is possible to define a level of income (a development threshold) below which income does not count toward capability, similar to the way typical income tax schedules do not tax income below a certain exemption level. In this calculator, national capability is calculated as the sum of all individual incomes, excluding income below the development threshold.

Capability is measured in market exchange rate (MER) terms, while the development threshold is expressed in Purchasing power parity (PPP) terms and then converted to country-specific values using the ratio of MER and PPP exchange rates appropriate to each country.

This capability is combined with responsibility to calculate a Responsibility and Capability Index, which is taken as a measure overall obligation to act.

For more information, see The Climate Equity Reference Project approach to Equity Benchmarking.

The development threshold defines an income threshold below which an individual's income, whatever country they may reside in, is taken to be exempt from the calculation of national fair shares.  Which is to say that income below the development threshold is not taken to contribute to national capability, nor are emissions corresponding to consumption below this threshold taken to contribute to national responsibility

This threshold can be set between $0 and $20,000 per person per year (in Purchasing Power Parity terms). For reference, a development threshold of $7,500 PPP per person per year, which is a bit above a reasonably-defined global poverty line based on empirical observations, is the standard setting presented to the user.  

Lower settings can be informative, but very low settings are difficult to justify as equitable.  Countries like India, which are home to large populations of very poor people, are considered to have much more capability when the development threshold is set to $0 than when it is set to $7,500, but this is only evidence of the problematic nature of such settings. Think of income tax systems, and consider that  developed countries almost universally “exempt” extremely poor people from their tax bases.  Very low development thresholds are inconsistent with the conventional progressive approach that virtually all societies have adopted for the purpose of income taxation, and they are difficult (if not impossible) to justify in equity terms.

For more information, see The Climate Equity Reference Project approach to Equity Benchmarking.

See also Luxury Threshold.

The Responsibility and Capability Index (RCI) combines measures of responsibility and capability (using a user-specified weighting) into a combined indicator of national obligation.

The RCI is then used to straightforwardly calculate each country's fair share of the global climate effort --  a country's fair share of the global effort (say, in total tons of mitigation required) is proportional to its RCI.

A country's RCI is affected by its income distribution, because both responsibility and capability are calculated in terms of a user-specified development threshold. For any non-zero development threshold, the resulting effort-sharing allocation, if interpreted as a climate tax, is mildly progressive. in other words, a dollar of income that is just above the development threshold is “taxed” at the same rate as a dollar earned by a billionaire.

For more information, see The Climate Equity Reference Project approach to Equity Benchmarking.

A nation's overall fair share of the global climate effort is calculated as a percentage of that global effort -- whether mitigation or adapation related -- and is based on the country's share of the global responsibility for causing climate change and capability for addressing it. These are expressed in a Responsibility and Capability Index, which is calculated based on user's own preferred interpretation of national responsibility and capability. These preferences are set in the panel to the left labeled Calculator Settings, and a core subset of them are also accessible in the Equity Settings panel. 

Critically, a nation's fair share is not seen in domestic terms, though its mitigation potential of course is. The CERP views climate as a global commons problem that can only be solved within a high-cooperation international regime. Such a regime can only be established if each Party sees others to be doing their fair shares in the face of the common challenge.  In practice, of course, each country will decide, on the basis of its own specific considerations (e.g. it’s own view of costs, co-benefits and political-economic tradeoffs) what fraction of its fair share of the global effort it will attempt domestically, and what fraction it will make off shore” by supporting action in other countries.

The global mitigation requirement is the “mitigation gap” between emissions under a global Business-as-Usual pathway and emissions under the specified global mitigation pathway. In any given year, for any given BAU and mitigation pathway pair, this gap can be expressed as a number of Gigatonnes of CO2 or CO2equivalent. This is the number of tons to be mitigated in that year. This global mitigation requirement can be allocated to individual countries, in proportion to their Responsibility and Capability Index, to determine their fair share of the global mitigation effort.

A mitigation pathway is a global emissions trajectory that is designed to, over time, keep the climate system within a given carbon budget, or to keep temperature increases below a certain limit. The more stringent the budgetary or temperature limit, the higher the level of global ambition.

The Climate Equity Reference Calculator supports three mitigation pathways. They range from the 1.5ºC standard pathway, which is an emergency mitigation pathway by any definition, to the G8 pathway, which is based on the (politically influential) targets specified in the G8’s 2009 Declaration in the Italian town of L’Aquila.

  • The 1.5ºC standard pathway is based on the 1.5ºC pathway published by Climate Action Tracker, and is estimated to have a greater than or equal to 50% probability of staying below 1.5ºC in 2100. The pathway is based on the median of the scenarios reported in the IPCC’s Fifth Assessment Report (WGIII) that have at least a 50% probability of staying below 1.5ºC. CAT reports a single all-gas median pathway; we disaggregate it into Fossil CO2, LULUCF and non-CO2 pathways using the non-CO2 pathway from RCP 2.6.
  • The 2°C standard pathway is based on the 2ºC pathway published by Climate Action Tracker, and is estimated to have a greater than 66% probability of staying below 2ºC in 2100. The pathway is based on the median of the scenarios reported in the IPCC’s Fifth Assessment Report (WGIII) that have at least a 66% probability of staying below 2ºC. CAT reports a single all-gas median pathway; we disaggregate it into Fossil CO2, LULUCF and non-CO2 pathways using the non-CO2 pathway from RCP 2.6.
  • The G8 pathway, for its part, is not calibrated to a specific temperature threshold, but is based on the politically influential targets specified in the G8’s 2009 Declaration in the Italian town of L’Aquila.  The L’Aquila text specifies only that the peak must be “as soon as possible” and omits the reference year against which goal the 50% global reductions by 2050 is to be calculated. In our rendering, its peak year is 2020, and the maximum annual rate of post-peak emissions decline is 6.0%. (The late peak requires very rapid reductions in order to reach its 50% in 2050 specification, and this despite its relatively larger budget.)  The pathway's 2012 to 2100 CO2 budget is ~1600 GtCO2, which is well above the largest of the IPCC's budgets, the one that is given a 33% chance of staying below 2ºC.  One can safely say that it is “very likely” to exceed 2ºC by 2100. 

For much more information on all of this, including a comparison of these pathways to the IPCC's emissions budgets, see the Mitigation Pathway Overview.

In these calculations, a country or region’s share of the Global Mitigation Requirement is proportional to its Responsibility and Capability Index.  The Responsibility and Capability Index can also quite properly be used to estimate national fair shares in a global adaptation effort.  Not that it can help us to estimate the global adaptation need, or the adaptation need of any given country, but it does offer a way to think about national fair shares of any monetized, global, climate-related effort.  

(Global adaptation need is properly estimated as a function of projected temperature change and national vulnerability.  At the moment, in the Calculator, all we offer is a user-defined parameter that is specified as a percentage of projected Gross World Product.)