Glossary

Acknowledgements

The Climate Equity Reference Calculator is a general equity reference tool, designed to allow the user to specify their own preferred equity benchmarks (largely based on indicators of capability and responsibility) which they can then use to evalute national pledges of action, relative to national fair share implied by those benchmarks.  

The Calculator was developed by Tom Athanasiou & Paul Baer of EcoEquity and Sivan Kartha & Eric Kemp-Benedict of the Stockholm Environment Institute, who also developed a specific effort-sharing approach, the Greenhouse Development Rights framework (since been generalized into the Climate Equity Reference framework). Most of the initial Calculator programming was also done by Eric, with the assistance of Douglas Wang. Tyler Kemp-Benedict did most of the user-interface design and implementation. More recently, Christian Holz has joined the CERP team, and among much else, has become a key team programmer. The core funding for these effort has been provided by the Stockholm Environment Institute, the Rockefeller Brothers Fund and Christian Aid. 

The core of the Climate Equity Reference framework is still the dynamic Responsibility and Capability Index approach.  However, the CERP approach has been substantively generalized, and much more generalization and extension is planned for the future.  

We'd also like to thank Kirk Smith, who as far as we can tell invented the Responsibility and Capability Index, or at least the approach that it embodies. (We thought that we had done so, but in fact Kirk beat us by over a decade!) See Kirk R. Smith, Joel Swisher, and Dilip R. Ahuja, "Who pays (to solve the problem and how much)?," in Peter Hayes and Kirk Smith (eds.), The global greenhouse regime: Who pays?, United Nations University Press/Earthscan, London, 1993.

Adaptation cost as a % of GWP

Estimates of the cost of a adaptation vary widely, and depend on a wide range of assumptions. The Climate Equity Reference Calculator does not assume any particular cost, but rather permits the user to specify an estimate of the cost.  The cost specified by the user is an annual cost, as a percentage of Gross World Product, that is assumed for simplicity to be constant over the entire time period.

This hypothetical cost estimate -- added to the mitigation cost estimate -- is used (in the Country Report and the "Fair Share" table view) to estimate fair shares of total costs.  

Adaptation Need

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.)

Business as Usual

Any effort-sharing framework (as opposed to resource-sharing frameworks that divides up a fixed emissions budget) requires baselines. This is because “effort” must be measured against a baseline, and – by definition – it should be a “no effort” or “no policies” baseline.  

The construction of such baselines is challenging, but plausible projections can be made. 

In this system, we have approached this problem in a straightforward manner.  Our baselines are derived from an existing set of standard sources: UN Population Division, IMF, US EPA, McKinsey and Company. We update and calibrate these to be consistent with the most current available annual emissions data, based on fossil fuel CO2 from numerous other sources.

For a much more detailed discussion, see Definition, sourcing, and updating of the emissions baselines.

Capability

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.

Climate Equity Reference Framework

The Climate Equity Reference Calculator is a general purpose climate equity reference tool, designed to allow the user to specify their own preferred interpretation of national responsibility and capability for climate action, which in turn is used to determine each country’s fair share of the global climate effort.

The core of the Climate Equity Reference framework is the dynamic Responsibility and Capability Index approach. For more information about this approach, and the Climate Equity Reference Project more generally, see About the Climate Equity Reference Project.

Development Threshold

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.

Domestic emissions

The equity reference calculator assigns each country a mitigation fair share (and, indirectly, an emissions allocation). It does not specify what portion of that fair share should be discharged domestically versus internationally (by way of financial and technological support). A country's actual domestic emissions trajectory will thus depend on the cost of domestic mitigation opportunities relative to other countries, and the participation in international mechanisms for providing or receiving financial and technological support for mitigation.

Here, as an indicative guide to thought, the country emission graphs include a (dotted green) line that shows the path a country's domestic emissions would follow they fell below the national BAU at the same rate as global emissions fell below the global BAU.

Domestic mitigation

Mitigation funded by a country or region and carried out within its own borders. 

Domestically-funded mitigation

Mitigation funded by a country or region and carried out within its own borders.

Critically, national fair shares of the global mitigation requirement are not seen in domestic terms. The Climate Equity Reference Calculator rather 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 best to do 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.

Emissions elasticity

Emissions elasticity expresses how rapidly emissions increase as income increases. With each percent increase in income, emissions increase by some percent. The elasticity is defined as the ratio of these numbers:

emissions elasticity = %difference in emissions/%difference in income

By default, emissions elasticity is set to 1.0. That is, within countries, individual emissions are taken to be proportional to individual income, which is generally consistent with empirical research. However, the user may want to examine the implications of emissions elasticity being somewhat less than or somewhat greater than 1.0:

  • emissions elasticity < 1.0: Emissions grow more slowly than income
  • emissions elasticity = 1.0: Emissions are proportional to income
  • emissions elasticity > 1.0: Emissions grow faster than income

This control allows for different values for the emissions elasticity. It can be used for sensitivity analysis, or if there is good reason to think that the emissions elasticity is different from the default.

Elasticity is a standard concept in economics, and discussions can be found in standard textbooks.

Emissions embodied in trade

Embodied emissions are emissions generated during production and transport of a good. National emissions inventories typically assign embodied emissions to the producing country: for example, if China produces a widget that it exports to the US, the emissions generated in the manufacture of the widget would be assigned to China. However, many have argued for assigning at least some of the emissions embodied in the widget to the consuming country. The calculator's standard setting follows standard practice and assign all emissions to the producing country. If however you select Include emissions embodied in trade, all the emissions embodied in traded goods are assigned to the consuming country.

Emissions Intensity

Emissions Intensity is a measure of the efficiency of a country’s economic activity, in terms of greenhouse gas emitted per unit of economic output. It is defined as greenhouse-gas emissions divided by Gross Domestic Product, and can be calculated in CO2-only terms or it can include non-CO2 gases.

Equity Settings - What they are and how to use them

The Climate Equity Reference Calculator does not produce one, single, "correct" result.  Rather, it offers a set of controls, and when you click past this Equity Settings page you'll have the opportunity to change them at will.  This page, on the other hand, contains only the key equity parameters, the ones which you use to specify how ambitious a climate transition you'd like to model, and how you want to interpret the core parameters defining responsibility and capability.

Choose your preferences. You can always change them later.  

Level of Global Ambition

First, chose a mitigation pathway. You have three options, which are carefully defined to represent three politically distinct storylines. You can read more about them here.

Common but Differentiated Responsibilities and Capabilities

The core of the Equity Reference Calculator is the Responsibility and Capability Index. The controls in the center of the Equity Settings page determine how national RCIs are calculated.  The key thing to note here is that while the the Calculator's fair share model is defined in terms of a country’s responsibility and capability, both the responsibility and the capability calculations can be done in stronger or weaker terms.  For a detailed discussion of the issues and choices here, see . . . 

Relative Weight for Historical Responsibility vs Economic Capability Act

The user has the flexibility to select the relative weighting of each. If one considers the two to be equally foundational, one can weight them equally (50% capability: 50% responsibility). If one considers capability to be of primary importance and responsibility to not require separate consideration, one can select a weighting of 100% capability and 0% responsibility) (or vice versa). Or, one can choose anywhere in between. 

For a much longer discussion of these topics, see The Climate Equity Reference Project approach to Equity Benchmarking.

Fair Share

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.

Global Mitigation Pathways / Level of Global Ambition

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.

Global Mitigation Requirement

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.

Greenhouse Development Rights (GDRs)

Greenhouse Development Rights was a ground-breaking equity reference framework based upon national responsibility and capability for climate action, and national (development and adaptation) need.  It has been generalized into and superceded by the Climate Equity Reference framework.  The core of the Climate Equity Reference framework is still the dynamic Responsibility and Capability Index approach.  However, the CERP approach has been substantively generalized, and much more generalization and extension is planned for the future.  

Historical Responsibility Start Date

Here the user specifies the initial year in the calculation of cumulative emissions for the purposes of assessing a country's Responsibility, which is defined as cumulative emissions (arising from consumption above the user-specified development threshold).

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

Incremental Costs

Estimating the incremental costs of climate action may be the most difficult challenge in all of climate economics. All estimates, without exception, are thick with assumptions both explicit and hidden. This Calculator makes no attempt to sort out the many issues here. Rather it provides users with the controls below, by which they can themselves estimate the global incremental mitigation and adaptation costs associated with the mitigation pathway that they have themselves chosen.

The one decision we have allowed ourselves to make is how to default the estimated incremental costs. We have chosen to default both to incremental global mitigation costs and incremental global adaptation costs to 1% of Gross World Product. In so doing, we have ignored the many obvious links between greater mitigation ambition and greater mitigation cost, and the many reciprocal links between greater mitigation ambition and lower adaptation (and loss & damage) costs.

The cost estimates given here affect only a few Calculator readouts. Just below, the mitigation cost estimate is combined with the Global Mitigation Requirement associated with the selected Global Mitigation Pathway to calculate a global average incremental mitigation cost, per tonne of CO2e. Later, in the Country Report and the "Fair share" table, it will be used to express the per capital fair share in financial terms. All other calculations in the Calculator are done in tons, not dollars.

Kyoto Obligation

The Kyoto Protocol is an agreement under which the world’s industrialized countries commited to limits on greenhouse gas emissions. Some countries complied with the Kyoto protocol emission limits, but some did not ratify, and some withdrew from the agreement. Views differ on how this should affect fair shares going forward, and thus, the Equity Reference Calculator allows the user to select whether "Kyoto obligations" are to be included or excluded when calculating national fair shares and evaluating national pledges.

If they are included,  then countries like Canada which not met their Kyoto target must reduce their emissions from their actual level in 2012 to their Kyoto target before any further reductions are counted towards their global (Responsibility and Capability Index-based) fair shares. The effect is that Kyoto non-compliers have fair shares going forward that are larger by an amount equal to the amount by which they exceeded their targets. All other countries have somewhat smaller fair shares, because the shared global climate-related need (which is divided among countries on the basis of responsibility and capability) becomes smaller by an amount equal to the aggregate amount by which Kyoto non-compliers exceed their Kyoto targets. 

There are three different ways in which Kyoto obligations can be treated.

  • They can be included for all countries. Thus, the US and Canada are treated as if they were still parties to the Kyoto protocol.  This allows the calculator to take account of the moral, if not legal, obligations that were implied by the original signature (the US) or ratification (Canada) of the Kyoto Protocol. More generally, it highlights the significance of non-compliance as a form a “free riding” – an issue that goes far beyond Kyoto. 
  • They can be excluded for all countries, which means that Kyoto non-compliance is ignored.  The Kyoto Protocol thus has no bearing on future fair share.  This option, importantly, is the default. 
  • They can be included for all countries except the US and Canada, which are not or are no longer parties to the Kyoto protocol, regardless of their previous intent to comply.  

Land-use emissions

Emissions from land use and land cover change are net releases of greenhouse gases that result from the management of land. These can include deforestation (which typically releases CO2), afforestation and reforestation (which typically store CO2), different agricultural or forestry practices that affect carbon stored in plants or soils, and other sources. To include land-use emissions, check this control. For more information about land-use emissions, see the IPCC Special Report on Land Use, Land-Use Change, and Forestry. And see Kate Dooley and Sivan Kartha, The risks of relying on tomorrow’s ‘negative emissions’ to guide today’s mitigation action, SEI Working Paper No 2016-08.  

Luxury Multiplier

The luxury multiplier provides an additional parameter for controlling the progressivity of the calculation of capability.  It applies a multiplier to income above the luxury threshold in the calculation of national capability. (E.g., a luxury multiplier of 2 causes income above the luxury threshold to count for twice as much as income below the threshold. It is analogous to setting a highest tax bracket in an income tax schedule.) The affect of such weighting is to shift obligation to the individuals at the very top of the global income distribution.  (Note, the luxury multiplier is enabled only when the "Progressive between thresholds" box is ticked.)

Luxury threshold

The luxury threshold is disabled by default, and when enabled it defaults to a figure ($100,000) that approximates the annual income (in MER or market-exchange rate dollars) of the top 1% of the global population -- the "global one percent."

When enabled (by checking the "Progressive between thresholds" box), once income rises above the development threshold, a linearly increasing percentage of that income (and the associated emissions) are counted towards national capability (and responsibility), until, when the luxury threshold is reached, it is fully counted toward national capability. The effect is to shift obligation up the global income scale. This is a simple analog to a progressive income tax, with a zero tax bracket up to the Development Threshold, and a maximum tax bracket starting at the Luxury Threshold. (See also luxury multiplier, which allows the user to apply a multiplier to income about the luxury threshold in the calculation of capability.)

Note that, while this has been provided in the Climate Equity Reference Calculator as a simple and defensible implementation of a progressive way to calculate national capability, it is by no means the only possibility. The options for a globally progressive allocation of fair shares are under-researched, but further study and better data collection can will presumably yield other sensible alternatives. 

Mitigation cost as % of GWP

Estimates of the cost of a mitigation vary widely, and depend on a wide range of assumptions. The Equity Reference Calculator does not assume a particular cost, but rather permits the user to specify an estimate of the cost.  The cost specified by the user is an annual cost, as a % of GWP, that is assumed for simplicity to be constant over the entire time period. The specified cost also determines a global average (not marginal) per-ton carbon-dioxide mitigation cost.

This hypothetical cost estimate -- added to the adaptation cost estimate -- is used (in the Country Report and the "Fair share" table view) to estimate fair shares (national and per capita) of total costs.  (The specified cost is not used in calculating fair shares of the mitigation effort, which are expressed in terms of tons.)

Mitigation Fair Share

A country's mitigation fair share is its fair share of the global mitigation requirement.  It is proportional to both the stringency of the mitigation pathway and the country's Responsibility and Capability Index

A developed country, with relatively large fractions of total global responsibility and capability, typically has a mitigation fair share that is larger than it’s domestic mitigation potential.  That is, a mitigation fair share that is larger than any that it can efficiently discharge within its own borders. 

A developing country, with relatively small fractions of total global responsibility and capability, typically has a mitigation fair share that is smaller than its domestic mitigation potential.  That is, it contains mitigation potential that must be used in order to realize a high-ambition global transition.  In practice, this means that it must be "matched" with support provided by developed countries that need it in order to discharge their mitigation fair shares. 

Mitigation funded by other countries

Mitigation funded by one country or region, but carried out within the borders of another. This mitigation is considered to count as (at least in part) an action of the country providing the support, though of course the terms of the mitigation would be as negotiated with the host country.

Mitigation funded in other countries

Mitigation supported by one country or region through finance and technology, but carried out within other countries by any of a number of possible means – tech transfer, supporting the Green Climate Fund, and so on. 

The fraction of a country's mitigation fair share that is discharged through international support is not specified by the Equity Reference Calculator, but rather would depend on the cost of domestic mitigation opportunities relative to other countries' mitigation opportunities, and the participation in international mechanisms for providing and receiving financial and technological support for mitigation.

Mitigation Smoothing

The Equity Reference Calculator offers two ways to calculate a country's fair share in a given year from its Responsibility and Capability Index (RCI).

The first way is simply to multiply the global mitigation requirement in a given year by the country's RCI in that same year.

The second way recognizes that meeting a given year's mitigation fair share will require investments to be planned and made over a period of time. In fact, incremental investment costs may occur years before the mitigation benefits are reaped. So, the second method -- termed “mitigation smoothing” -- is to multiply the global mitigation requirement in a given year by the average of the country's RCI over the preceding years.

"Mitigation smoothing" is selected by checking this box.  When it is active (and it is by default) the RCI is not taken to be the RCI in the year that is being reported (e.g. 2020). Rather, it is taken to be the average of the RCIs between the present year (e.g. 2014) and the year being reported (e.g. 2020).  This average better expresses that national RCI as it will be during the relevant investment period.  

Note: Only mitigation investments (denominated in tons) are smoothed.  When expressed in financial terms, estimated fair shares are not smoothed.  

Non-CO2 gases

The most important of the greenhouse gases (GHGs) is carbon dioxide (CO2), because it makes the largest single contribution to planetary warming (see this figure on radiative forcing in the IPCC Fourth Assessment Report). However, non-CO2 gases are also important drivers of climate change, notably methane (CH4) and nitrous oxide (N2O). The default case here includes all gases. To exclude the non-CO2 gases, un-check this control.

Pledged Effort

The Equity Reference Calculator assesses the national pledges that countries have submitted to UNFCCC Secretariat. (The official Annex 1 submissions and non-Annex 1 submissions are available on the UNFCCC website, and helpful compilations are available from the Climate Action Tracker and Climate Interactive websites. We rely upon these roll-ups and do not attempt to collect additional information about pledges. In a few cases, we adjust our pledge database to take account of important, but not yet widely reported, changes in national pledges.

To this point, almost all mitigation pledges are given for the year 2020. Some countries have submitted both an “unconditional” pledge, which they intend to meet unilaterally, and a more ambitious “conditional” pledge, which is contingent on other countries raising their own mitigation ambition and/or providing financial and technological support.

While this Equity Reference Calculator views national fair shares as the sum of domestic mitigation and financial support for international mitigation, only the mitigation pledges can currently be assessed.  This is because explicit pledges tend to be announced only for domestic mitigation alone, and not for financial support for international mitigation (not to mention adaptation). Some wealthy (high capability) countries do provide some support for international action of various kinds, but they do not generally do so in a manner that is explicitly reported and accounted in a coherent manner.  Because of this lack of explicit and credible information, it is not possible to consider financial support for international mitigation in the assessment of a country's pledge. 

Progressivity

When describing a tax, “progressivity” refers to how tax burden, as a share of income, changes with income. Under a progressive tax, higher incomes are taxed at a higher rate than lower incomes. In this calculator, progressivity can be varied in a number of ways; the most important is that individual income (and associated emissions) below the development threshold can be excluded from the calculation of national capability and responsibility. To explore alternative, more progressive, schemes, the calculator also allows for an upper luxury threshold. When it is enabled, the marginal tax rate, if you will, increases linearly from zero to its maximum value between the development and luxury thresholds.

Income distributions are used for each country to calculate individual-level responsibility and capability as a step towards the calculation of national responsibility and capability, and in turn national fair shares. Each country will of course decide for itself how its share of the global climate burden will be divided among its citizens. However, it is instructive to consider the fair shares (in financial terms) that derive from the responsibility and capability of individuals at different income levels in different countries. (See the indicative estimate of the per capital fair share, as expressed in financial terms.  It is given in the Country Report, and in the "Fair share" table view.)

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

Responsibility

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.

Responsibility and Capability Index (RCI)

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.

Responsibility weight

The Responsibly and Capability Index is a combined indicator of responsibility and capability, which are weighted equally -- 50/50 --  in the default case (i.e., they are averaged). This setting allows the user to select an alternative weighting for responsibility. (The capability weighting will automatically set at 1 minus the responsibility weighting.)

Note that, for most countries, the weighting it matters little, because responsibility and capability tend to be (but are not always) highly correlated. 

Type of Pledge

Many countries have expressed their national emissions mitigation pledges in the form of an unconditional pledge and a conditional pledge. The unconditional pledge is weaker (lower in ambition), but will be met unilaterally. The conditional pledge is stronger (higher in ambition) but becomes active only if other countries satisfy certain requirements relating to increasing their own ambition with respect to mitigation pledges and/or the provision of finance and technology.

Note that some countries have offered only a single pledge, and sometimes an ambiguous definition of it as well.  In rare cases -- to illustrate the implications of high- and low-ambition interpretations of such pledges -- we have denoted the weaker interpretation to be 'unconditional' and the stronger interpretation to be 'conditional'.