Ethics and Climate

Donald Brown

Ethics and Climate - Donald Brown

At the UN Climate Talks, Thinking About Equity May Require Understanding the Conditions of Mutual Trust

Editor’s Note: The following entry is by guest blogger, Dr. Idil Boran, from  York University in Toronto, Canada. Dr. Boran has previously reported on equity and justice issues that arose in the recently concluded Bonn intercessional meetings of climate negotiations under the UNFCCC. This latest report was made at the conclusion of these negotiations during which almost no progress was made in defining equity under UNFCCC by the Ad Hoc Working Group on Durban Platform For  Enhanced Action (ADP), a mechanism under the UNFCCC that seeks to achieve a adequate global climate agreement, despite a growing consensus among most observers of the UNFCCC negotiations that nations need to align their emissions reductions commitments to levels required of them by equity and justice if the world is going to prevent extremely dangerous climate change.

climate justicenow

At the UN Climate Talks, Thinking About Equity May Require Understanding the Conditions of Mutual Trust

The UN Climate Conference held in Bonn, Germany, June 4-15, 2014, concluded in a generally positive tone. Much work has been done before COP 20 in Lima, where negotiators are expected to produce a fully written draft of the new agreement.

International talks on climate change have taken many twists and turns since the UNFCCC came into effect. In the current round of negotiations important shifts are occurring. As explained in a previous post, the new platform of negotiations favors the concept of global participation, where every nation is expected to do its part in some capacity. This is to replace the idea of common but differentiated responsibilities, which was the guiding principle of the negotiations in the Kyoto era. This principle was specially opted to capture a sense of equity within a binding global treaty. The current focus on global participation is to facilitate agreement and induce greater participation. But does this shift imply that the new agreement will have to make a compromise on the issue of equity?

Moral and political philosophers tend to think about equity in substantive terms, as claims about how to apportion the burdens and the benefits as part of a collective venture. The thinking is usually that of identifying an appropriate criterion of equity (a guiding principle) and then articulating an allocation of responsibilities from this criterion.

This way of thinking can be applied to many topics arising within the Framework Convention. Take, for example, the new issue at the heart of the multilateral negotiations: the Warsaw Mechanism on Loss and Damage associated with climate impacts in developing countries that are particularly vulnerable to the adverse effects of climate change. When the issue of loss and damage is raised, a standard approach that comes to mind is that of prescribing an allocation of the costs associated with loss and damage (human, economic, as well as non-economic costs) by a criterion of equity.

For example, historical accountability provides a morally powerful criterion. This is the idea that those who are historically responsible for the problem of climate change should provide the resources to deal with loss and damage. Ability to pay provides another criterion. Here the idea is that developed countries should take up the costs, simply because they are more wealthy. These arguments have been made for mitigation efforts, and they can also be made as new issues arise, such as the issue of an international mechanism on loss and damage.

But the reality is far more complex. However neat these substantive arguments are, they do not capture the layers of discussions that actually take place. In fact, most of the discussions regarding the Warsaw Mechanism, at this point in time, are not over substantive questions. They are focused on deciding on the rules and procedures, and the composition of the Executive Committee, whose mandate will be to develop the details of the mechanism. But the questions that arise at this procedural level are no less interesting. As discussions continue, developing countries who feel threatened by the effects of climate change will press for greater representation within the Committee, and developed countries, such as the United States and the E.U. will press more on the importance of securing the right team of experts regardless of country representation.

But why are developing countries vulnerable to the effects of climate change are pressing for more seats on the Committee? Clearly, when it comes to decisions made by the Executive Committee, they worry that their interests will not be taken into account, unless they secure greater representation.

So, it looks like there is a problem of trust that needs to be addressed at the heart of the deliberations. Within rightful conditions of collective decision-making, equitable terms of cooperation can be captured and agreed upon. And this is exactly what the new round of negotiations aims to achieve by 2015, with more flexibility conferred to countries in making their contributions to the climate effort. What remains to be done, then, is to work on the conditions that will promote trust between parties.

More than neat arguments from first principles, this may require specially talented people, with strong diplomatic skills working on the ground, who can foster a sense of building bridges, and a feel for working together on a global problem. This will also require the building of strong international institutions that put greater emphasis than ever on transparency, accountability, and governance.

At this juncture then, if equity is the concern, there are reasons to invest in understanding what, if at all, can generate more trust between parties at the UNFCCC. Figuring out what it takes to secure mutual trust is more an art than strict rational argumentation. It has something to do with creating a welcoming and inclusive atmosphere, as opposed to a hostile one where all hold their cards close to their chests. It therefore makes sense for academic researchers interested in the ethical, political, and legal aspects of climate talks to tune in to these dynamics.

As for the institutional structure of the UNFCCC, adopting the right institutional rules and procedures can help in fostering mutual trust. That’s why the new multilateral assessment and review processes under development are of special significance. So is the effort to agree on a common metric on emissions reduction, so to allow all parties to pitch in their contributions in a coherent way, and work together toward ratcheting them up in the future. This may not be a magic solution to the climate problem, but it can set the foundations of cooperation that’s not only equitable but durable too. If successful, it can set an important precedent.

That’s why all eyes will be on Lima in December 2014…


Dr. Idil Boran. Associate Professor &

Director of the Certificate Program in Practical Ethics

Department of Philosophy, Faculty of Liberal Arts and Professional Studies

Core Faculty Member

Institute for Research and Innovation in Sustainability (IRIS)

York University, Toronto Ontario


10 Reasons Why “Contraction and Convergence” Is Still The Most Preferable Equity Framework for Allocating National GHG Targets .


(The Contraction and Convergence Equity Framework)

I. Introduction

Perhaps the most challenging policy issue raised by climate change is how to fairly allocate responsibility among nations, regions, states, organizations, and individuals to reduce global greenhouse gas (ghg) emissions to non-dangerous levels. This problem is generally referred to as the problem of “equity” in the climate change regime. It a central issue in climate change policy formation because each government policy on reducing the threat of  climate change is implicitly a position on that government’s fair share of safe global emissions. In addition, climate change will continue to get worse unless each country reduces its emissions to its fair share of safe global emissions.  Therefore, “equity” is not only a challenging issue in forming climate policies, it is perhaps the most critical policy question facing the international community.

This article identifies 10 reasons why the equity framework known as “contraction and convergence” (C&C) is the most preferable of all the equity frameworks under serious discussion around the world.  The end of this paper will acknowledge some alleged limitations of C&C yet explain why these limitations should be dealt with in one of several possible ways while adopting the C&C framework internationally.

C&C was first proposed in 1990 by the London-based non-governmental Global new book description for website-1_01Commons Institute. (Meyer, 2000) ( GCI, 2009) Basically, C&C is not a prescription per se, but rather a way of demonstrating how a global prescription could be negotiated and organized. (Meyer, 1999:305) Implementing C&C requires two main steps. As a first step, countries must to agree on a long-term global stabilization level for atmospheric ghg concentrations. Although a warming limit of 2 degrees C has been preliminarily agreed to in international negotiations, subject to the acknowledged need to examine whether the limit should be reduced to 1.5 degrees C in studies that are underway, once a warming limit is finalized it must be translated into a ghg atmospheric concentration goal and then a global ghg emissions budget can be calculated. As a second step, countries need to negotiate a convergence date, that is a date at which time the emissions allocated to each country should converge on equal per-capita entitlements (“convergence”) while staying within the carbon budget. During the transition period, a yearly global limitation is devised which contracts over time as the per-capita entitlements of developed countries decrease while those of most developing countries increase. C&C would allow nations to achieve their per capita based targets through trading from countries that have excess allotments.

And so the heart of C&C is the idea that justice requires that rights to use the atmosphere as a carbon sink must be based upon the idea that all human beings have an equal right to use the global commons, the Earth’s atmosphere. Because it would be impossible to achieve equal per capita emissions allocations in the short-term, C&C allows higher emitting nations to converge on a equal per capita target at some future date thus giving these nations some time to achieve an equal per capita target goal.

II. 10 Reasons To Support C&C

C&C is the most preferable equity framework  for the following reasons:

1.  Climate change is a classic problem of distributive justice. Distributive justice holds that all people should be treated as equals in any allocation of public goods unless some other distribution can be justified on morally supportable grounds. And so distributive justice entails the idea that at all allocations of public goods should start with a with a presumption of equal rights to public goods. Yet, distributive justice does not require that all shares of public goods be equal but put puts the burden on those who want to move away from equal shares to demonstrate that their justification for their requested entitlement to non-equal shares is based upon morally relevant grounds. Therefore someone cannot justify his or her desire to use a greater share of public resources on the fact that he or she has blue eyes or that he or she will maximize his or her economic self-interest through greater shares of public goods because such justifications fail to pass the test of morally supportable justifications for being treated differently. Because C&C ends up at some time in the future with equal rights for all individuals to use the atmosphere as a sink, it is strongly consistent with theories of distributive justice. Although distributive justice would also allow for other morally relevant considerations to be considered in allocating ghg emissions that diverge from strict equality, including such considerations as historical ghg emissions levels, these other considerations can be built into a C&C framework either by negotiating the convergence dates in a C&C regime or in side-agreements on such issues as financing technologies for low-emitting nations at levels that would allow them to achieve per capita emissions limitations.  C&C therefore is strongly consistent with theories of distributive justice because equal per capita emissions is the ultimate outcome of C&C even if that outcome is modified to take into account other legitimate equitable issues in negotiations by changing the convergence date or in side-agreements that finance compliance for poor nations that need assistance in achieving equal per capita emissions limitations.

2.  Allocating ghg emissions on an equal per capita emissions basis is consistent with the virtually universally recognized ethical idea that all people should treat others as they wish to be treated. And so basing allocations on equal rights is  the least contentious of all ethical theories of how to allocate public goods. Although there are are other ethically relevant facts that arguably should be considered in an allocation of ghg emissions such as economic capability to reduce emissions  or historical emissions levels, these considerations are more controversial ethically particularly in  regard to how they are operationalized in setting a numeric targets and therefore are more amenable to negotiated settlements on issues such as when convergence on equal per capita levels will  be achieved rather than in setting basic allocation target levels.

3. Equal per capita emissions levels are also consistent with human rights theories about the duty to prevent climate change. That is, human rights are based upon the uncontroversial ethical theory that humans should treat each other as they would like to be treated because all people, regardless of where they are,  should be treated with respect. Since the outcome of C&C is equal per capita rights, it is completely consistent with the idea of treating all people with equal respect, the foundation of human rights obligations. Because climate change undeniably violates several non-controversial human rights including the right to life, security, and food among other rights, climate change is widely acknowledged as a human rights problem. If climate change allocations are considered to be in fulfillment of human rights duties, then arguments based upon economic self-interest in setting ghg emissions targets are not an acceptable justification for avoiding human rights obligations. This is so because human rights obligations are viewed to ethically trump other values such as economic self interest or utility maximization as has been explained in significant detail in recent entries on this website. If human rights are violated by climate change, costs to those causing climate change entailed by policies to reduce the threat of climate change are not relevant for policy. That is if a person is violating human rights, he or she should desist even if it is costly to them. Therefore because a C&C framework has the strongest obvious link to human rights, if it were agreed to by the international community it would provide a strong argument against those who refuse to limit their emissions to an equal per capita level on the bases of cost to them.

4. Setting a ghg emissions target based upon distributive justice requires consideration of facts determined by looking backward, such as levels of historical ghg emissions, and issues determined by looking forward, such as what amount of the global commons should each individual be entitled to for personal use. Only equal per capita entitlements to the use a global commons satisfies future focused allocations issues without ethical controversy.  And so an allocation that converges on equal per capita emissions allocations sometime in the future is more than any other allocation framework likely to be seen as universally just as far as future entitlements issues are concerned. And so, the C&C should be supported because it is most consistent with equal entitlements to use global commons resources.

5, The C&C framework is the simplest of the dozen or so equity allocation frameworks which have been seriously considered in international climate change negotiations. Because it is simpler, it will likely be easier to negotiate than the other equity frameworks which have received serious consideration. Its simplicity is derived from the fact that its focus is narrowly on climate change justice issues. Thus it is not complicated by other global injustice issues which are not climate change related yet which are considerations in some other equity frameworks . For instance, other proposed ghg allocation formula try and remedy economic injustice among nations, issues which are worthy of international attention yet greatly complicate the ethical issues which need to be considered in setting ghg targets. Because C&C is simple, it is very pragmatic.

6. Objections to equal per capita allocations have sometimes been made by representatives from high emitting nations such as the United States because of the enormous ghg emissions reductions which would be required of it to reach equal per capita emissions levels of diminishing allowable safe global emissions.  Yet emissions reductions that would be required of high emitting nations under other proposed equity frameworks would be even steeper because they take into considerations issues such as, for example, historical emissions, economic wealth of nations, and ability of nations to pay. For this reason C&C holds the best chance of being accepted by the international community compared to other equity frameworks provided other issues that raise legitimate equity concerns including historical emissions levels are taken into account in some way in climate negotiations. These other justice concerns should be understood to be refinements of C&C rather than replacements of C&C because the C&C framework was always flexible enough to take into account additional issues relevant to distributive justice.

7. Many observers of international global efforts to achieve a solution to climate change argue that there has been too much emphasis on the obligations of nations while obligations of individuals and regional governments have largely been ignored. These observers argue that this focus on nations has helped high-emitting individuals and regional governments to largely escape public scrutiny. Because C&C obligations are premised on determining the obligations of nations based upon equal per capita shares, C&C can be seamlessly applied to state and regional governments and individuals around the world. If, for instance, a C&C framework determines that the world should converge on a per capita emissions target of 2 tons per person by 2025, it is therefore a straightforward deduction to argue that all individuals around the world  should limit their emissions to be below 2 tons per person by 2025 at a minimum.

8. Some of the issues that proponents of other equity frameworks have argued  should be considered in allocating national emissions targets such as historical emissions or the level of economic development in poor countries are already in serious consideration in international climate change negotiation agenda focused  on such matters as: (a) financial responsibility for adaptation, (b) responsibility for loses and damages for climate change, and (c) financing of climate friendly technologies for developing countries. Because of this the ethical issues raised by historical emissions or economic ability of nations to achieve a per capita allocation could be relegated to other issues already being negotiated in international climate change negotiations while emissions allocations targets are allocated on the basis of C&C.

9. Establishing a norm that each person is only entitled to emit ghgs on an equal per capita basis would also help to draw lines about other contentious ethical issues raised by climate change such as how to count responsibility for historical emissions. Determining how to translate historical emissions into legal obligations raises a host of contentious issues including when to start counting historical emissions. This question could be simplified by first determining reasonable per capita emissions at various moments in history. In addition, determining  liability for future excess emissions could be simplified if there was an agreement on acceptable per capita emissions. And so looking at the problem of climate change through a per capita lens helps draw lines about other climate change policy matters which will need to be faced. Therefore the  establishment of a C&C framework would help with other policy questions that must be faced in the future.

10. Many have argued that responsibility for reducing ghg emissions should not only be based upon production of ghgs within a nation, the current presumption of international negotiations, but on products consumed  in a nation but produced in another nations in processes which emitted ghgs.  Although this shift from production ghg to consumption related ghg as a way of establishing national responsibility to achieve ghg emissions reduction targets is not likely to happen in the short-term, those who desire to assign liability on the basis of consumption could also use the C&C framework more easier than other proposed equity frameworks.

III. Limitations of C&C

Other proposed equity frameworks were developed to deal with a few alleged  limitations of C&C. (As we have explained, C&C was always flexible enough to deal with additional issues relevant to distributive justice and therefore these alleged criticisms did not take into considerations the inherent flexibility of C&C.)

For instance, a second allocation formula which has received serious attention by the international community is the Greenhouse Development Rights Framework ( GDR) (Baer et al., 2008). GDR was developed, according to its proponents, because C&C does not leave adequate ghg emissions to allow developing nations to develop to levels that would allow them to escape grinding poverty. And so, proponents of GDR argue that any targets developed under a C&C framework will not be fair to poor nations and therefore will not be accepted by developing nations. We agree that several additional equitable issues  including the justice dimensions of historical emissions levels must be dealt with for a C&C approach to be fair to low-emitting poor countries because emissions targets simply based upon equal per capita emissions to allocate the extraordinarily small carbon budget that is left to avoid dangerous climate change will leave almost nothing for low emitting nations to grow economically. The questions is not whether these issues need to be considered in setting targets, but rather how they are considered while maintaining the moral force of equal per capita rights to use the atmosphere as a carbon sink.

The Brazilian government has also developed a proposed equity framework based upon the need to take historical emissions levels seriously. Both the proposed GDR framework and the proposed Brazilian framework more directly deal with legitimate justice issues which are not expressly initially dealt with under C&C.  Yet C&C can be adopted in combination with other agreements and adjustments to C&C assumptions that deal directly with the equitable issues more directly considered by the other proposed equity frameworks. For instance, the convergence dates in the C&C framework can be modified to take into consideration s0me historical emissions issues. In addition, separate agreements on such matters  as financing carbon friendly technologies in poor, low emitting nations can deal with issues of need to assist developing nations achieve otherwise just ghg emissions targets.

In summary, some of the alleged limitations of  C&C can be dealt in other agreements while retaining the basic structure of C&C.  And so, for the 10 reasons above, the C&C should be adopted by the international community not withstanding the legitimate need to consider other issues relevant to distributive justice in setting ghg emissions reduction targets including levels of historical emissions and financial ability of poor nations to comply with per capita emissions limitations. For this reason, C&C is the most preferable and practical equitable framework for allocating climate change obligations among governments.


Baer, P., Athanasiou, T., Kartha, S., and Kemp-Benedict, E., (2008). The Greenhouse Development Rights Framework, Second Edition, November 2008.

Global Commons Institute, (GCI), ) 2010.

Meyer, A., (2000, Contraction and Convergence, The Global Solution to Climate Change, Ttones, UK: Green Books,


Donald A. Brown

Scholar in Residence and Professor, Sustainability Ethics and Law and Professor, Widener University School of LawPart-time Professor, Nanjing University of Science Information and Technology, Nanjing, China



On the Extraordinary Urgency of Nations Responding To Climate Change on the Basis of Equity.


This  article seeks to explain in understandable terms why nations must not only aggressively respond to climate change but respond at levels required of them by equity if the world is going to have any hope of avoiding dangerous climate change. And so, this article seeks to help citizens around the world understand why their nations must create climate change policies consistent with their equitable obligations and that if their nations fail to respond on the basis of equity, there is vey little hope of an adequate global solution emerging that has any potential of avoiding catastrophic climate change.

Once again there has been some renewed interest in responding to climate change this week in response to the announcement by the National Oceanic and Atmospheric Administration (NOAA) that carbon dioxide (CO2) atmospheric concentrations have reached 400 ppm (parts per million). This concentration of CO2 is not only higher than experienced in the last 3 million years of Earth’s history  (Kunzig, 2013), it is additional evidence that the world is rapidly running out of time to prevent dangerous climate change.  NOAA posted on its website Wednesday night, May 9, that the daily average for CO2 was 400.03 ppm. (Kunzig, 2013)   The last time the concentration of the CO2 reached this mark, horses and camels lived in the high Arctic and seas were at least 30 feet higher. (Kunzig, 2013) This sea level  rise would  inundate major cities around the world and cause harm to hundreds of millions around the world when temperatures finally responded to these elevated greenhouse gas (ghg) atmospheric concentrations.

Although this story made it to the front page of the New York Times, (see Schuetze 2013), the US press continues to fail to educate American citizens fully about the seriousness of the problem that the world is facing particularly in regard to the urgent need of nations to take immediate steps to reduce their emissions to their fair share of safe global ghg emissions. has previously examined the failure of the US press to communicate to American people the importance of the equity issue in formulating US policy. (See, The US Media’s Grave Failure To Communicate The Significance of Understanding Climate Change as A Civilization Challenging Ethical Issue.Yet, as we will explain, in light of the rapidly decreasing amount of time remaining for the world to prevent dangerous climate change, there is now more than ever a need to increase political support at the national level around the world for the adoption of policies on climate change that reflect each nation’s fair share of safe global emissions.

rich countriesWhen almost all nations around the world agreed to the 1992 United Nations Framework Convention on Climate Change (UNFCCC), they promised  to adopt policies and measures to limit warming based upon “equity” to prevent dangerous anthropogenic interference with the climate system. (UNFCCC, Art. 3) Up until very recently it was possible for nations to ignore that they had a responsibility to reduce their ghg emissions to levels based upon “equity.” And so many, if not most, nations have been entering international climate negotiations as if they need only look to their national economic interest to determine what ghg emissions reductions commitments they need to make under the UNFCCC. However, now that the world is running out of time to prevent dangerous climate change, the urgent need of nations to reduce their emissions to levels required of them on the basis of equity and basic fairness is now obvious and undeniable. This was not the case only a few years ago.  For instance, just three years ago it was possible for the United States to ignore what was required of it as a matter of basic fairness because nations were happy when the United States made any commitment to reduce its ghg emissions having refused to do so from the early 1990s through 2010. Any US commitment was viewed as a positive step. And so, when President Obama made a voluntary commitment in 2010 in Copenhagen to reduce US emissions by 17% below 2005 levels by 2020, it was widely celebrated throughout the international community even though most observers knew this commitment was far short of what justice required of the United States. Yet just two years later in Qatar, the same US commitment was almost universally condemned on justice grounds. (See: Qatar: Bumping Up Against Climate Change Limitations On Human Activities Makes Ethical and Justice Issues Unavoidable) 

The importance of each government entity’s responsibility to limit their emissions to their fair share of safe global emissions has become undeniably obvious to most observers of international climate negotiations now that it has become clear to all that there is precious little time for the global community to avoid dangerous climate change. The central importance of the need to get nations to respond to climate change on the basis of “equity” becomes very obvious once a number of scientific aspects of climate change are fully understood. However, too few people understand these scientific aspects of climate change and the press is failing to educate citizens about these issues.













To fully understand the importance of national responses on the basis of “equity” it is necessary to understand some features of climate change that make it unlike any other environmental problem facing the world. The atmosphere is like a bathtub, it has limited volume. Nations have been filling up the atmospheric bathtub since the beginning of the industrial revolution in the late 1790s. Because CO2 is long-lived in the atmosphere, the bathtub continues to fill up with CO2 even if rates of CO2 emissions slow down somewhat unless all ghg emissions are reduced to the rate at which the Earth’s natural carbon cycle can remove CO2, an amount which is less than 20% of existing emissions levels. Decreasing ghg emissions does not prevent global atmospheric concentrations from increasing unless they are cut back globally by huge amounts. And so to prevent dangerous climate change nations have to do much more than cut back on the ghg emissions levels that they are entering the atmosphere, they have to cooperate to prevent the level in the bath tub from reaching levels that will cause dangerous climate change. As we shall see, this is a level that the world is fast approaching. Furthermore because CO2 is well mixed in the atmosphere it makes no difference where on Earth the ghgs come from, the atmospheric concentrations of ghg continue to rise without regard to location of the source of emissions.

What makes the current climate change threat so ominous is that the levels of CO2 that have been building up for over 200 years are quickly approaching levels that could trigger dangerous climate change as emissions are increasing in many parts of the world.

In our experience, most Americans don’t understand the scale of the climate change facing the world. In Copenhagen in 2010 the international community agreed to set as a goal warming limit of 2°C not withstanding there are some scientific evidence to believe that the warming limit should be lower at 1.5 °C. The 2°C warming limit was chosen because there is strong scientific evidence that warming above 2°C could trigger rapid nonlinear climate change thereby threatening hundreds of millions of people around the world and the ecological systems on which they depend. Even if 2°C warming doesn’t trigger nonlinear warming, this amount of warming will cause great harm around the world to people and places that have done little to cause climate change.

The following graph describes the staggering challenge facing the world if the international community desires to limit warming to 2°C.  The graph depicts three different emissions reductions pathways where the steepness of ghg emissions reductions needed to limit 2°C depend upon when global emissions levels peak, that is in 2015, 2020, or 2025. Despite over twenty years since the international community agreed in 1992 to adopt policies and measures based upon equity to prevent dangerous climate change, global ghg emissions levels continue to rise despite a global economic turn down in 2008. Global CO2 emissions grew 3 percent in 2011 and were estimated to rise 2.6 in 2012. (Morello, 2012).  Since the international community began to negotiate a climate change solution, rather then emissions levels diminishing they have  grown to 58 percent above the 1990 emissions level in 2012 (Morello, 2012). And so, the world is facing the urgent need to reduce ghg emissions at hard to imagine rates as seen in the following graph where the different colored lines on this chart represent different assumptions about climate sensitivity. This graph shows that if the world waits to act together to prevent ghg emissions from rising until 2020 or 2025, the world will need to reduce ghg emissions at staggering reduction levels after the peak years.

three reductions pathways





(Anderson, K.. 2012)

On the basis of the magnitude of the ghg emissions reductions challenge facing the world, mainstream scientists around the world are now emphatically trying to get the world’s attention about the urgency of the need to act dramatically to prevent dangerous climate change. Yet there has been little discussion in the media about the importance of equity in national responses to this global emergency coupled with the fact that one needs to understand other aspects of the climate change problem to fully understand the importance of requiring nations to reduce their emissions based upon “equity.”

Once one identifies an atmosphere ghg concentration level that will serve as a goal for preventing dangerous warming it is a relatively straightforward calculation to identify the remaining amounts of ghg emissions that can be emitted worldwide to prevent atmospheric ghg concentrations from exceeding the maximum concentration goal. This calculation is the basis for determining an emissions budget. Because there is some uncertainty about climate sensitivity, that is how much warming the Earth will experience at different atmospheric ghg concentrations, different atmospheric ghg concentration goals create different levels of probability of limiting warming to 2°C.  The following chart identifies the quantity of ghg emissions in gigatons of CO2 equivalent that the world may emit to achieve different levels of probability that the 2° C warming limit will not be exceeded. Therefore we see from this chart that if the entire world is assumed to be allowed to emit no more than 886 gigatons (Gt) of CO2 equivalent, this budgetary limit creates between a 8% and 37%, with a best estimate of 20%, probability that temperatures will exceed the warming limit of  2°C.   At the upper end of this chart, a 1437 Gt CO2 budgetary limit creates a probability of between 29 to 70 probability, with a best estimate of 50%, that the  2°C warming limit will be exceeded.

The chart also shows that if the world emits ghgs at levels projected at 56 Gt per year, then, assuming that the world chooses to live with a budget of 886 Gt CO2 which gives the world an 80% probability that future warming will be limited to 2°C, then after12 years there will be zero emissions left in the budget.  The chart also demonstrates that even if the world chooses to run the risk of accepting a 50% probability that the 2°C warming will be exceeded then world can only emit greenhouse gases at projected levels for 22 years.

As gloomy as this picture in regard to the remaining global ghg emissions budget, we have not yet explained why getting nations to commit to reduce their emissions to levels required of them by equity is so important and indispensable for thinking clearly about how the world must respond to the threat of climate change. And so, now, for the first time, we can explain the importance of “equity” in guiding international responses to climate change.















Returning to the use of a bathtub as a metaphor for the atmosphere, we note that there is already elevated levels of ghg (metaphorically water) in the bathtub that have risen to current levels from over 200 years of human activities. That is CO2 has increased in the atmosphere from 280 ppm to 400 ppm since the beginning of the industrial revolution. If we assume that atmospheric concentrations of CO2 equivalent should be limited to 450 ppm to give the world a 50% chance of keeping warming from exceeding the 2°C warming limit, atmospheric concentrations have increased already by120 ppm from pre-industrial levels and only 50 ppm of atmospheric space are  left to allocate to the entire world.  The 120 ppm increase in atmospheric CO2 concentrations that has already been put into the bathtub by human activities has overwhelmingly been caused by activities in some rich, developed countries much more than poor developing countries.  The following chart shows which countries have contributed the most elevated concentrations of CO2 in the atmosphere.
cummualative over time

(EPA, 2002)

And so some countries more than others have contributed far more than others to elevated ghg concentrations. Given that there’s only 50 ppm of atmospheric space left to allocate (assuming and atmospheric goal of 450ppm giving approximately a 50 % chance of exceeding  the 2°C) and some developing countries desperately need to use the remaining atmospheric space to escape grinding poverty, it is obviously unfair or inequitable to require all countries to reduce emissions by the same amount.

Percapita nationaFurthermore, the above chart demonstrates that some countries including the United States, Canada,  and Australia, for instance, far exceed others in per capita levels of emissions from their citizens compared to other countries such as India.

If it is determined that the entire world must reduce its emissions by 80% below 1990 levels to prevent dangerous climate change, high-emitting nations or governments around the world, including the US, Canada, and Australia, will need to reduce their emissions to even greater levels on the basis of equity and fairness. To require each nation or government to reduce emissions by the same percentage amount would freeze into place unjust emission levels for high-emitting governments and very low emissions rates for poor developing countries.  For this reason, almost all the nations of the world, including the United States in 1992 when it ratified the UNFCCC, agreed that each nation must reduce its emissions on the basis of “equity” to prevent dangerous climate change. (UNFCCC, 1992: Art 3, Para 1) If all nations need only reduce their emissions by equal percentage amounts, then a high-emitting nation like the United States that emits ghg at rate of 17.3 tons per capita would be allowed to emit at a level 10 times more per capita than a country like Vietnam that emits 1.7 tons of ghg per capita. (World Bank, 2012b) As a result, all nations have agreed that national targets must be based upon fairness or equity.

Given that the entire world has only 50 ppm of atmospheric space left to allocate to give the world a reasonable expectation of preventing dangerous climate change, the equitable and fairness dimensions of national ghg emissions reductions commitments become obvious and crucial to increasing the ambition of nations to reduce their ghg emissions. Yet most citizens seem completely unaware of the equity issues entailed by climate change and many high-emitting nations are ignoring their equitable responsibilities.

However, the ability of nations to ignore what equity requires of them will become more and more difficult as the world wakes up to the hard-to-imagine stringent carbon budget that the world must face to avoid catastrophe warming. In addition the longer nations wait to respond to climate change on the basis of equity, the more difficult it will be in the future to do so because the steepness of their emissions reductions pathways needed to comply with what equity requires increases the longer nations wait to respond appropriately.


Anderson, Ken, (2012) , Climate Change Going Beyond Dangerous, Brutal Numbers, Tenous Hope,

EPA, (2002), CO2 emissions by country (

Kunzig, Robert, (2013) National Geographic News,  Climate Milestone: CO2 Level Passes 400 ppm,  National Geographic,

Morello, (2012), Global CO2 Emissions from Fossil-Fuel Burning Rise into High-Risk Zone, Scientific American,

Open Source, (2013)

 World Bank, (2012), CO2 Emissions (Metric Tons Per Capita),

United Nations Framework Convention on Climate Change  (UNFCCC), (1992),



Donald A. Brown

Scholar In Residence,

Sustainable Development Ethics and Law

Widener University School of Law

dabrown57@gmail. com