Global Justice and Climate Change: How Should Responsibilities Be Distributed?
Global Justice and Climate Change: How Should Responsibilities Be Distributed?
Global Justice and Climate Change: How Should Responsibilities Be Distributed?
Delivered at
Tsinghua University, Beijing
March 2425, 2008
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David Miller is Professor of Political Theory at the University of Oxford and Official Fellow in Social and Political Theory at Nuffield College, Oxford. He graduated from Cambridge University, then went on
to receive his B.Phil. and D.Phil. in Politics at Balliol College, Oxford.
He has been a Lecturer in Politics at the University of Lancaster and the
University of East Anglia. He is a fellow at the British Academy. He is
the author of numerous publications, including Principles of Social Justice
(1999), Citizenship and National Identity (2000), Political Philosophy: A
Very Short Introduction (2003), and National Responsibility and Global
Justice (2007).
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I
What can a political philosopher contribute to the current debate about
climate change, and how to prevent its reaching catastrophic levels? One
might think that this was a matter, in the first place, for scientists, whose
job it is to study the causes of humanly induced global warming, and the
effects of different degrees of warming on the natural environment and
the human societies that depend on it; in the second place for economists,
who can work out the most efficient way for humanity as a whole to adjust its behavior so that the warming can be brought under control and
kept within acceptable levels; and finally for political leaders and statesmen, whose task it is to take the economists recommendations, turn them
into concrete policies, and then persuade ordinary citizens to do what is
required of them. The problem is both urgent and difficult to solve, politically at least. Do we need philosophers, with their fine distinctions
and their skeptical questioning of taken-for-granted assumptions, poking
their noses into it?
I believe that the answer to this question is a very definite yes. We need
political philosophers to think and talk about climate change, not as an alternative to the work of the other three groups but as an essential complement to itindeed as a bridge between the empirical researches of climate
scientists and economists and the practical work of politicians. What
philosophers are uniquely positioned to do is to spell out the reasons we
have to change our behavior to avoid damaging climate change, in other
words to ground the ethical and political obligations that we will have to
accept if a solution is to be found. Although there is now widespread acceptance that humanly induced climate change is a reality (there are still
a few pockets of climate-change denial, in the United States especially,
but their number is dwindling by the day), people can respond to that
fact in very different ways. Consider some of the most frequently heard
responses: Whats so bad about climate change? I like the warmer summers. We may have a problem now, but well soon find a technical fix
that sorts it out. Global warming may be bad, but theres nothing we can
do about itlook at the rate at which China is building power stations.
I agree theres a problem, but there are others we should tackle first
global poverty, for instance. These responses may often be self-serving,
but they are not obviously wrongthey deserve to be taken seriously and
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I want to narrow the question down still further by arguing that these
principles apply, in the first place, to nation-states as the collective agents
capable of coordinating individual behavior on a scale that can meet the
challenge of climate change. That is, we should see the problem of distributing responsibility as occurring in two stages. First, the costs of combating global warming are distributed to states in the form of required
reductions in greenhouse-gas emissions or actions they must take to offset
the effects of the warming that will nonetheless occur or both. Second,
states distribute these costs among their citizens according to guidelines
that are agreed internally (and that may be expected to vary somewhat
from one state to the next). For example, they may decide to control emissions by taxing the industries that mainly produce them, or they may
decide to give each individual citizen a carbon budget that limits their
use of emission-generating resources to a total that they can exceed only
by buying a slice of somebody elses. The reasons for this two-stage approach are partly practical: I can see no other way to tackle climate change
than through an international agreement that first of all sets an overall
target in the form of a cap on greenhouse emissions worldwide, and then
breaks that down into targets for each nation individually, so that each
country has an obligation to reduce its level of emissions to the figure and
by the date specified in the agreement.3 In other words, we must have an
improved version of the Kyoto agreement, and we must ensure that all
nations are brought under its aegis. Were we to try to move directly to the
individual level, then even if we could perform the necessary calculations
and give each person an emissions target, we would simply have created
a massive collective-action problem with no agency capable of solving it.
Each person would have an incentive to overshoot their target, and there
would be no effective constraint to stop them from doing so.
There is also a more principled reason for preferring a two-stage approach. We should want our climate-change policies to encroach as little
as possible on national self-determination. Rather than imposing policy
solutions from above, it is far better to agree upon targets for each nation,
adapt to the effects of the emissions that have already occurred. The distinction between adaptation and mitigation is highlighted in S. Caney, Cosmopolitan Justice, Responsibility, and
Climate Change, Leiden Journal of International Law 18 (2005): 74775; and S. Caney, Climate Change, Justice, and the Duties of the Advantaged, in Critical Review of International
Social and Political Philosophy (forthcoming).
3. I shall not discuss the further question whether, once emission targets have been allocated in this way, countries should be allowed to engage in emissions trading whereby those
nations that wish to exceed their targets can buy additional allowances from other societies.
This is a complex subject that deserves closer investigation than I can give it here.
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and then to allow policies for meeting those targets to be decided internally, ideally through a process of democratic debate. Practical changes of
the kind required to combat global warming have significant implications
for other areas of national policy, especially economic development and
employment. They impinge also on questions of social justice, since if individuals are going to be asked to bear certain costs when climate-change
policies are implemented, decisions have to be made about how those
costs will be distributed. If, for example, energy prices rise substantially
when new cleaner forms of energy generation such as wind power are introduced, should vulnerable groups such as pensioners be given protection in the form of subsidies? Such questions will be answered differently
in different societies, according to prevailing conceptions of social justice.
Since climate-change policies can be successfully implemented only if
there is general consent to their introduction, allowing nations to map
their own route within the constraints on emissions set internationally
not only respects their rights of self-determination but is likely to produce
a higher level of compliance in the long run.
In saying this, I am taking issue with pessimists about climate change,
who believe that the problem cannot be tackled unless a collective policy
to combat global warming can be coercively enforced, and for that you
would need something like a world government. According to this view,
societies that fail to meet their assigned targets must be punished, and that
implies an authority willing and able to impose the appropriate sanctions.
Since no such authority exists, nor is one likely to come into existence,
the climate-change problem is at present insoluble. Perhaps, if things get
sufficiently bad, and the ability of the human race to survive on earth at all
comes into question, people will be willing to sign a Hobbesian contract
to create a global Leviathan with the power to enforce its environmental
policy. Appealing to rights of self-determination, in this context, simply
misses the nature and gravity of the problem we are facing.
In my view, such pessimism is unjustified. A global Leviathan is not
necessary in order to combat global warming effectively, nor indeed is
there any reason to think it would succeed: there would be massive resistance once it began to impose conditions on hitherto independent
nation-states. What we need instead is a climate-change regime based on
voluntary cooperation between states, where the role of an international
authority is to help coordinate the actions of these states by setting emission targets and other policy goals, and then to monitor compliance with
these targets and identify defaulters. My assumption here is that so long as
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other greenhouse gases. It is well known that these levels are the cumulative effects of emissions going back for at least a century or so, the side
effects of industrialization in those countries that are now the most economically developed. The much cited polluter pays principlethe principle that those who pollute the environment should pay to clean up the
mess they have causedseems to suggest that the past should matter in
this way. But is this really so?
Next I want to examine an intuitively plausible principle for limiting
greenhouse-gas emissions, namely, the principle that each person has an
equal right to emit such gases. Applying this principle to the problem of
global warming would mean first setting a ceiling on overall emissions at
the point where no further warming (or more strictly no warming that
imposes unacceptable costs) will take place, and then dividing that total
equally among the worlds inhabitants. Every country with excess levels
of emissions per capita would then be required to reduce them until the
excess was eliminated; conversely, nations that currently fall short of their
emissions entitlement would be permitted to emit more greenhouse gases
up to that point. This, of course, would be very costly for most of the developed societies, but it might nonetheless seem fair. But is it?
I will argue that neither principle can carry the weight that it is being
asked to bear in the debate over climate change. The main burden must fall
upon another principle, which I will call the principle of equal sacrifice.
This first of all draws a line between societies in which poverty is endemic
and those that either do or could lift their members above the global poverty threshold, and then requires people in the latter group of societies to
reduce emissions to the agreed global ceiling in such a way that the per capita cost of mitigation is the same for each society. Costs, I will argue, should
be measured in terms of economic growth forgone. Having accepted its
emissions reduction target, calculated on this basis, it would then be up to
each nation-state to decide whether to share the resulting burden equally
among its members, or to ask some citizens to pay a larger per capita cost.
After defending equal sacrifice as the main principle that should guide
the distribution of responsibilities in an international agreement on climate change, I turn finally to the problem of partial compliance. Suppose
that such an agreement has been negotiated: what if some countries refuse
to sign, or some, having signed, fail to do what is required of them under
the agreement? This, only too obviously, is not just a hypothetical question. What does fairness then require of the societies that have signed the
agreement? Must they do precisely what the agreement says, or more than
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that, taking up the slack as it were, or less than that, since others are not
playing fair?
I begin, then, with the principle of historic responsibility, which not
surprisingly is popular among developing-society advocates, to whom it
seems obvious that the main burden of adjustment to climate change must
fall on those societies that have been the biggest emitters of greenhouse
gases in the past. But we need to look closely at the principle that is being
appealed to here. As I noted above, it is often said to be an application of
the polluter pays principle, which holds that if an agent does something
that is harmful to otherspollutes a river with chemicals, for example
then that same agent should bear the costs of remedying the harm, either
by removing the pollution, if that is possible, or compensating the victims.
That principle seems sound enough in its own right. It acts as a disincentive to would-be polluters, but also and perhaps more fundamentally it
acknowledges the fact that we are agents who make an impact on our surroundings, and who should be held responsible for that impact, both in
cases where the impact is a positive onewe should reap where we have
sownand in cases where it is negative, in the sense of being harmful to
others.5 This applies in the first place to individual people, but it can also
be extended, under certain conditions, to collectives. If I work hard as part
of a team that produces some collective good, then I am partly responsible
for that good and deserve to have some share in it. But equally if the team
imposes external costs on others, by damaging the common environment,
for example, then I share in responsibility for those costs and can properly
be made to pay compensation.
So far, so good. But now the first problem we face in applying the
polluter-pays principle to historic emissions of greenhouse gases is that
the people responsible for the emissions themselves have mostly left the
sceneonce we look back beyond a generation or soand it is their descendants who are being asked to pay the costs. Many people find it objectionable to hold people today responsible for what their predecessors have
done, as it seems they are here being required to. Now it is true current
people cant be blamed for what their ancestors didthat seems evident.
But perhaps they can nonetheless be held responsible for failing to make
appropriate redress. Take a very simple case. Suppose my grandfather stole
a valuable picture from your grandfather, and that picture remains hang5. For a particularly good statement of the rationale for this principle, see H. Shue,
Global Environment and International Inequality, International Affairs 75 (1999): 53145,
at 53345.
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ing in my hall today, even though I know about the circumstances of its acquisition. By failing to return the picture to its rightful owneryou, your
grandfathers only surviving heirI am responsible for perpetuating an
injustice. And this idea can be applied not only to individuals but also to
collectives. Suppose two neighboring villages have organized themselves
as farming co-operatives. Sometime in the past, members of one village
raided the other and stole a valuable piece of farm machinery that they
continue to use to this day. Even though the present-day inhabitants were
not themselves involved in the raid, by holding on to the machine, they
are perpetuating an injustice. Their responsibility now is to return the machine to the first village, and probably also provide some compensation
for the losses its inhabitants have suffered in the meantime.
Can this reasoning be applied to the case of greenhouse-gas emissions?
To reach that conclusion, a number of difficulties have to be surmounted.
The first is to identify the continuing agent who bears the responsibility. In
the two examples I have just given, continuity was provided by the family
in one case, and by the farming co-operative in the other. Individuals bear
responsibility as members of these transhistorical units. Can we point to
anything analogous where climate change is at stake? Critics point out
that in the developed societies that historically have contributed most to
emissions, the actual emitters have been individual people, independent
corporations, public companies, and so forthin other words, there is
no single agent but a whole variety of agents, many of them no longer in
existence today, who have been causally responsible for present-day levels
of atmospheric CO2 and so forth.6
Should we respond to this problem by pinning responsibility onto
states, on the grounds that states bear responsibility for whatever happens
within their borders, whether or not they directly initiated the activity
in question? If a state allows a polluting factory to send sulfur dioxide or
other harmful chemicals into the air, it then becomes responsible for that
pollution even if, as seems likely, it played no direct role in generating it.
And states typically survive over many generations, so in that sense they
are transhistorical units of the kind we are looking for. But there are some
difficulties with identifying states as the bearers of responsibility in this
way. What are we to say about cases where regimes have changed, perhaps by revolutionary means, or cases in which state boundaries have been
6.See, for example, S. Caney, Environmental Degradation, Reparations, and the Moral
Significance of History, Journal of Social Philosophy 37 (2006): 46482.
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altered so that different groups of people, and different means of production, now fall under their auspices? Should we hold the present German
state responsible for the pollution produced by heavy industry under the
German Democratic Republic, for example? If so, on what grounds? Furthermore, if we hold states responsible for rectifying the damage caused
by earlier generations occupying the same territory, ultimately the costs of
rectification have to fall on the people they govern. Taxes have to be raised,
for example, to pay for the costs of cleaning up pollution, or compensating
its victims. The state itself does not have an independent stock of resources
that can be used for this purpose. So now we have to ask questions about
the relationship between states and the nations they govern, questions that
become particularly sharp in cases where the state is not democratic, and
where its actions, therefore, cannot be attributed to the popular will. Is it
reasonable to ask people today to bear responsibility for what their states
have done, or failed to do, by way of limiting greenhouse-gas emissions if
neither they nor their predecessors have had any control over state policy?
For this reason, someone who wants to appeal to historic responsibility
as a principle of fairness when allocating the costs of combating presentday global warming would do better to look beyond states as governing
institutions to the nations they govern. Nations are transhistorical units
of the right kind if we want to assign present-day members responsibility for what their predecessors have done, and to make them liable for the
consequences. Despite the fact that their membership is undergoing continual replacement, by natural births and deaths, and by immigration and
emigration, there is continuity between the generations, both in the form
of national identitypeople think of themselves as belonging to the same
cultural group as their forebears, and take pride in the historic achievements
of their countryand in the form of practices and institutions that persist
over time and play an influential part in determining peoples life chances
today. If we were to ask what explains the very different sets of opportunities that confront people living in different parts of the world, a large part
of the answer must concern national inheritance. By virtue of being born in
a developed society, in particular, you are able to take advantage of material
conditions that result from past practices and institutions. By parity of reasoning, if you inherit the benefits of economic development, and claim the
right to enjoy these benefits, by virtue of membership then you should also
be held responsible for the associated costs, which might take the form of
damage inflicted on third parties. There is more that needs to be said here
to ward off objections to the idea of national inheritance, but I am going to
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assume that the basic idea is sound.7 So if we return now to the specific case
of greenhouse-gas emissions, a person could not exempt himself merely by
pointing out that he played no part in producing these emissions in the past
and therefore bears no special responsibility to take corrective action now.
To such a person, it would be relevant to point out that he forms part of a
national unit that did play such a part, and that he benefits from the practices and institutions that allowed the emissions to occur, not just in some
accidental way but by virtue of his membership itself.
That, however, does not settle the matter, as I shall now try to show.
The real problems with the historic responsibility principle in the context of global warming are not that we cannot find relevant transhistorical
units to serve as the bearers of responsibilityas I have just suggested, nations are, in general, communities through which historic responsibilities
can be inherited. The problems concern, rather, the particular phenomenon we are investigating, namely, global warming caused by gas emissions.
Look back for a moment to the two examples that I used to introduce
the idea of inherited responsibilityyour grandfathers painting and the
stolen item of farm machinery. In each case responsibility relates to a clear
historic wrong. The examples rely on the fact that stealing the picture in
one case and stealing the machine in the other were acts of injustice of
which the original parties were culpable. Take that fact awaysuppose
that the picture was stolen because your grandfather refused to acknowledge a debt of comparable magnitude owed to mineand the argument
falls down. So can we say that a similar wrong occurred in the case of historic greenhouse-gas emissions? What kind of injustice was involved?
Attempts are sometimes made to exonerate past emitters of greenhouse gases on the grounds that they did not know that their actions were
liable to cause global warming, nor did they have any reason to know.
There is some debate in the literature about the date after which it became no longer reasonable to deny the link between humanly produced
gas emissions and rises in average global temperature. Most commentators
believe that by the mid-1980s climate science had advanced to the point
where the existence of such a link was overwhelmingly probable (though
it is noteworthy that the first IPCC report published in 1990 still sounds
some very distinct notes of caution about this).8 Let us then say that the
7. For a fuller defense, see my National Responsibility and Global Justice (Oxford: Oxford
University Press, 2007), chap. 6.
8.See the passages cited in R. Malnes, Climate Science and the Way We Ought to Think
about Danger, Environmental Politics 17 (2008): 66072, esp. 663.
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risk that anthropogenic gas emissions would cause harmful global warming had become common knowledge by about 1985. What of nations
whose members emitted significant quantities of greenhouse gases before
this time? They cannot be held morally responsible, or blamable, for these
emissionsmoral responsibility and blame require that the agent in question either knew or was in a position where he or she should have known
that the action in question was harmful. But these nations might nonetheless be held responsible in a wider sense that carries with it responsibilities to counteract the damage caused.9 Think of a case of pollution where
initially the polluter has no reason to think that the waste he is pouring
into the river is damaging to the environment. Subsequently it is shown
that lasting damage has occurred. The polluter then becomes responsible
for rectifying the damage, or providing compensation. This might be
defeasible in certain casesfor example, if the causal connection between
the waste and the resulting damage is very indirect, or if the polluter could
show that there were large compensating benefits, not only to himself
but to the wider community, from the process that produced the waste.
But otherwise the infliction of damage is sufficient to create remedial
responsibility even if the agent could not have foreseen it at the time
of action.
The problem here, once again, is not with the idea of historic responsibility itself. It is rather, I suggest, with the analogy that is being drawn
between greenhouse-gas emissions and pollution properfor example,
the release of chemicals that reduce the fertility of the land or are damaging to human health.10 To show that historic gas emissions were wrongful
in a way that would create remedial responsibilities, we would need to
explain in what sense they were harmful to human interests. At this point
we have to make some assumptions about the cumulative effects of different levels of greenhouse-gas emission over time. Without trying to resolve
any complex scientific questions, let me suggest three possible accounts of
the relationship between gas emissions and the damage they cause to the
human environment. The first is that the relationship is linear: each quantum of carbon dioxide, say, released into the atmosphere causes the same
incremental increase in surface temperature, and each degree of warming
9. In National Responsibility and Global Justice, I call responsibility in this sense outcome
responsibility in order to distinguish it from the narrower idea of moral responsibilitysee
especially chapter 4
10. For a fuller discussion of the limitations of the polluter pays principle in discussions
of climate change, see Caney, Cosmopolitan Justice, Responsibility, and Climate Change.
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effects of climate change, and they did not know what their successors
would do once those facts became known. It would after all have been possible to cut back sharply on fossil-fuel burning, air travel, and so forth. We
chose not to do this, of course, but it would be wrong to say that we had
no alternative.
So the argument about historic responsibility, in the earlier years,
would have to be made differently. If the effects of early greenhouse-gas
emissions were not significantly damaging in themselves, then to attribute
responsibility to the emitters we need to show that they were behaving
unfairly by denying later generations the chance to emit. In other words,
were it not for them, we would not be facing the problems that we now
face from future global warming, or at least not such severe problems. The
unfairness is not to be found in anything directly harmful that the early
emitters did, but in the inequality between early emitters and later generations, who now have to choose between allowing global warming to proceed apace, with potentially devastating results, and cutting back sharply
and at considerable cost on emissions now and in the future.
The argument is indeed sometimes made in this form. It can be expressed in terms of equal opportunities. Given that the emission of greenhouse gases becomes costly above a certain level, but the activities made
possible by this emission are beneficial to the emitter, everyone should
have an equal opportunity to benefit from emissions.15 Early generations,
however, were emitting at a level that could not be extended to everybody,
so they were denying others their equal opportunities. They were using
more than their fair share of the atmospheres absorptive capacity, and so
they were incurring what is sometimes called a natural or ecological debt.
For political philosophers, this argument inevitably brings to mind
John Lockes well-known theory of property acquisition. Asking how private ownership was possible in a world originally given by God to man in
common, Locke claimed that a person in the state of nature is entitled to
its much greater historical use of (and benefit from) the bridge? Chan supposes the latter, and
argues that this provides a good model for thinking about how to allocate the costs of combating climate change. Appealing though this analogy is, it depends on the assumption that each
crossing of the tree trunk slightly weakens it, together with the assumption that the bridge is
a jointly owned asset. I have argued, however, that we should not think of earlier greenhousegas emissions in these terms. Suppose instead that the trunk would last indefinitely under its
original pattern of use; it is only when group B starts to use it for trade that it begins rapidly to
weaken. Under these circumstances, it would seem natural for groups A and B to agree to share
the costs of the new bridge, perhaps on the basis of the relative future benefit that each group
expects to derive from it.
15. This argument is made explicitly in E. Neumayer, In Defence of Historical Accountability for Greenhouse Gas Emissions, Ecological Economics 33 (2000): 18592, at 188.
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remove resources from the commons for his own use as private property,
so long as there is enough, and as good left in common for others. The
person, Locke says, who takes a parcel of land as his private property does
no injury to others, any more than a person who drinks from a stream
injures a second person who had a whole River of the same Water left
him to quench his thirst.16 The principle here seems to be that where a
resource is potentially scarce, people can make use of it on the condition
that others coming after them have an equivalent opportunity.17 This is the
principle that early emitters of greenhouse gases are said to have breached.
They did not leave their successors a whole River of the same Water to
drink from.
Locke, however, went on to qualify this argument in one important
way. Perhaps recognizing that opportunities to acquire property, in land
especially, were no longer equal, in a world in which most resources were
already privately owned, he proposed that this was acceptable provided
that those whose opportunities to acquire were smaller or nonexistent
were benefited in other ways, so that overall their position was improved.
He famously remarked that although land was still relatively plentiful in
the Americas, a King of a large fruitful Territory there feeds, lodges and
is clad worse than a day Labourer in England.18 In other words, the English day laborer has not been injured by his inability to appropriate land,
because his employment by those who have done so has led to an increase
in his overall standard of living, using the position of a native American
as a benchmark. The idea here, then, is that when evaluating the extent of
opportunity, one should not look narrowly at any specific opportunity
such as the opportunity to appropriate unowned land, but at what the opportunity is meant to lead to, namely, a certain standard of life.
Could Lockes important qualification to his original principle of acquisition be used to get early emitters of greenhouse gases off the hook?
Could it be shown that although people in the present day no longer have
the same opportunity to emit greenhouse gasesthat is, they can no longer do so without seriously damaging effects, whereas their predecessors
16. J. Locke, Two Treatises of Government, edited by P. Laslett (New York: Mentor, 1965),
329, 333.
17. Jeremy Waldron has argued that Locke did not, in fact, impose this as a necessary
condition, even though he concedes that Locke went to some lengths to point out that this
condition was indeed satisfied in the state of nature. See Enough and as Good Left for Others, Philosophical Quarterly 29 (1979): 31928. If Waldrons reading of Locke is correct, the
position I am discussing is Lockean in spirit but not quite Lockes own.
18. Locke, Two Treatises of Government, 339.
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II
My purpose in these essays is to find principles that could help us to tackle
the urgent problem of global warming by reaching an international agreement to cut the emission of greenhouse gasesan agreement, I have argued, that must be seen to be fair to all parties in order to be effective. As
the UN Framework Convention signed by 152 countries at Rio in 1992 puts
it, nations should protect the climate system for the benefit of present
and future generations of mankind, on the basis of equity and in accordance with their common but differentiated responsibilities and respective
capabilities.1 My task, then, is to decide what equity means in this context,
and how these differentiated responsibilities should be allocated.
I argued in the first essay that relying on the historic responsibility
principle, which would require the costs of mitigation to be allocated
according to each countrys historic record as an emitter of greenhouse
gases, was far more problematic than is usually supposed. Although it is
often claimed that these historic emissions constitute a harm in the same
way as, say, pollution in the form of dumping hazardous waste, in fact the
claim goes through only if one appeals to something like a principle of
equal opportunity to emit greenhouse gases. The charge would have to be,
to use language borrowed from John Locke, that these early greenhousegas emitters did not leave enough and as good for others in the form
of an atmosphere capable of absorbing humanly produced gases without
generating harmful climate change. This introduces the first issue to be
addressed here, namely, whether a claim on the part of political communities today to an equal opportunity to emit greenhouse gases might be
grounded upon their members equal human right to emit such gases. If
such a right could be established, it would presumably not necessarily be
one that each person exercised individually. Instead, the implication of
recognizing an equal per capita right to emit greenhouse gases would be
that each societys permissible level of emissions would be a direct function of its population size. By mutual consent, the internal allocation of
emission rights could proceed on a different basis. But a fair international
agreement to control global warming would be one that first set a global
cap on emissions and then allocated targets to each political community
on the basis simply of the number of people who belonged to it.
1.Cited in M. Grubb, Seeking Fair Weather: Ethics and the International Debate on
Climate Change, International Affairs 71 (1995): 46396, at 463.
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the lowest incomes, for example, or presenting all the remaining bottles as a
thank-you present to the person who organized the party. Equal division is
just a simple, nondiscriminatory way of allocating the surplus wine.
But there are other cases in which we have deeper reasons for using
equality as our distributive principle. Among them are cases in which departing from equality would involve disrespect to those who receive less,
because it would fail to recognize them as members in good standing of
some social group. A paradigm case is the allocation of voting rights to
adult citizens. Even if we had the information that would allow us to use
some other principlevotes proportional to political expertise, for exampleit would be wrong to do so. It would undermine the equal status
of the citizens, and treat those who got fewer votes with disrespect. Here,
then, what matters is not so much the value of the resource that is being allocatedhaving one vote in an electorate of many millions is after all not
of great instrumental value to the voterbut the message that is conveyed
by distributing it in one way or the other.
Another circumstance in which equality is required by more than
shallow reasons is one where people have a right to some good, and the
quantity of good available is only just sufficient to meet all of their claims.
The underlying principle here is not itself a principle of equality3the
normative work is being done by the idea of rightsbut in the special circumstance just described, and perhaps by extension in certain cases where
there are insufficient resources to meet all claims, equality in distribution
becomes mandatory. Thus, bread must be distributed equally in a famine,
in the absence of differential claims of need, and to fail to do this would be
to infringe upon the rights of those who get smaller portions.4
If we return to the case of greenhouse-gas emissions, however, it seems
that there are only shallow reasons for favoring an equality rule. Such a
rule is relatively simple to apply, setting aside for the moment the difficulties in calculating net emissions, and it seems that nobody can claim they
are being discriminated against if such a rule is employed. These are obviously important considerations when complex international negotiations
are being undertaken, and may help to explain why the rule has enjoyed
the level of popularity in the academic literature that it has. But there do
3. This is shown by the fact that if more of the good becomes available, the surplus need
not be distributed equally.
4. This is not intended as an exhaustive discussion of the circumstances in which the
equal distribution of some resource is required as a matter of justicesee my fuller treatment
in Principles of Social Justice (Cambridge: Harvard University Press, 1999), chap. 11. Here I have
taken cases that might appear relevant to the emission of greenhouse gases.
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not seem to be any deeper reasons to support it. Insofar as this question is
addressed in the literature, the rule is treated as self-evidently fair. But how
could this be shown?
One possibility is to present the emission of greenhouse gases as a
natural or human right, which, therefore, belongs equally to all human
beings. But could gas emissions have that kind of fundamental status? I
assume that human rights are justified by showing that they correspond
to basic human needs: if the rights are not respected, people will be unable to lead minimally decent lives.5 Thus, food, shelter, and access to basic
medical care would all qualify as human rights in this approach. Could
we somehow bring gas emissions into this picture? Human beings plainly
have the right to breathe, and therefore the right to emit the quantity of
carbon dioxide that breathing produces. But moving beyond this, the
greenhouse-gas emissions produced by energy generation, transport, and
so forth are at most instrumental to basic human rights; that is, depending
on the circumstances, a certain level of energy generation might be necessary to produce sufficient food, heating, and so on for a particular group
of people. But this would indeed depend on the circumstances, and therefore on previous choices that have been made about technology and human labor. Consider a very simple example. A nation with enough land to
produce food to meet the needs of all its inhabitants might decide instead
to import most of its food in exchange for manufactured items. So, contingently, it requires the greenhouse-gas emissions produced by air, sea,
or road transport in order to fulfill the human right to food. But because
this has come about as a result of a political choice, these emissions cannot
themselves be presented as matters of human rights. People have human
rights to whatever is necessary to meet their basic needs as human beings,
but they cannot claim a right to whatever means they themselves prefer
to use to meet those needs.6 Rights, it is important to remember, always
impose obligations on others, who have to limit their own behavior to
meet the demands of the right holder. So we should not inflate them without thinking about the consequences of doing so. In a situation in which
global warming has become a major problem for humanity at large, it may
be necessary for countries that currently import large quantities of food to
stop doing so and go back to being more self-sufficient. To object to such a
5. For a full statement, see my National Responsibility and Global Justice, chap. 7.
6.On this point, see also T. Hayward, Human Rights versus Emissions Rights: Climate
Justice and the Equitable Distribution of Ecological Space, Ethics and International Affairs 21
(2007): 43150.
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that are used to meet basic needs in developing countries. The problem
with a simple equality rule is that it draws no such distinction. A unit of
carbon dioxide or methane emitted counts for the same no matter what
it is being used to produce. It might, of course, turn out that a regime of
equal per capita emissions gave all countries an adequate opportunity to
provide their citizens with minimally decent lives. But given the very different background circumstances in which countries find themselves, as
noted above, that is a risky assumption to make. Some nations can reasonably claim a greater allowance on the grounds that, even if they choose the
technology for energy generation that produces the lowest level of emissions, they still cannot meet subsistence needs under an equality rule.
There is one final point about the principle of an equal right to emit
greenhouse gases that deserves to be made here. Those who favor allocating national emissions quotas on an equal per capita basis notice immediately that this rule makes the size of the quota susceptible to changes in
population size. A country whose population increases gets more emission permits as a result, and this gives it no incentive to adopt policies of
population control, which must surely form part of the broader strategy of
environmental protection, as well as that of combating global warming. To
avoid this perverse result, it is routinely proposed that the quotas be based
on population numbers in some arbitrarily chosen year1990, for example.9 But now, if we let the clock run forward, this means that at some later
time people will not in fact have an equal right to emit greenhouse gases. If
you happen to live in a country whose population has increased since the
chosen date, your entitlement will be reduced. This consequence does not
seem to disconcert advocates of the equal per capita rule. But if there were
deep reasons in favor of equality, it surely should. If there is something
fundamentally unfair about one person having less of an entitlement than
another to emit greenhouse gases, then it is wrong for individual entitlements to depend on changes in population size for which they were not
personally responsible. What this confirms is that the case for the equality
rule is almost entirely a pragmatic one; its advocates think that it could
form the basis for an agreement between sovereign countries because of its
simplicity, and from that point of view fixing quotas according to population size at some historic moment is just another aspect of simplicity. But
once we look more carefully at the rule, we see that it overlooks important
considerations of fairness between people and between nations.
9.See, for example, Jamieson, Climate Change and Global Environmental Justice, 301.
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might be higher than this if the society chose to achieve its reductions by a
different policy route, but the calculation should be based on the cheapest
way of cutting emissions. It might be argued, however, that using such an
economic measure of costs overlooks large differences between societies
in existing GDP levels: in human terms, somebody who belongs to a middle-income society faces higher costs from any given percentage reduction
in economic growth than somebody who belongs to a high-income society.12 The argument here parallels the argument often made in defense of
the progressive income tax in domestic contexts, namely, that because the
marginal utility of income diminishes, the real cost to rich people of an
income reduction via tax is smaller than the same reduction would involve
for poorer people. I am not convinced that this intrasocietal argument
transfers easily to intersociety cases when we are thinking of societies all
of whose members are comfortably above the absolute poverty line I am
assuming we can identify. Notice that we are talking here not about actual
reductions in existing per capita incomes but about quite modest cuts in
projected increases.13 So the question is whether we have any reason to
think that such cuts will be more burdensome for people in middle-income societies than for people in rich societies. Suggestive evidence to the
contrary can be found by looking at happiness studies, which show very
little relationship between a societys average per capita income and the
felt happiness of its members once the income figure rises beyond a certain
point.14 A stronger case for progressivity can be made for societies whose
GDP puts them only a short distance above the global poverty line, so we
could envisage a more complex scheme of cost distribution where costs
were zero for members of societies with endemic poverty, then rose in line
12. This seems to be the view taken in M. Traxler, Fair Chore Division for Climate
Change, Social Theory and Practice 28 (2002): 10134. Traxler supports equal burdensomeness as the fair principle for allocating the costs of preventing climate change, but argues that
burdensomeness should be measured not in monetary terms but in terms of human welfare.
Apart from the familiar problems with using welfare as the currency of justice, I am not
convinced, for the reasons given in the text, that switching from monetary costs to welfare
costs will produce the result that Traxler wants, namely, that more will be required of the rich
societies.
13. The authoritative Stern Report on climate change estimates that the overall costs of the
measures needed to mitigate global warming are about 1 percent of the GDP, within a range of
-1 to 3.5 percent. This is against a background in which economic output in OECD countries
is predicted to rise by more than 200 percent by 2050, and by 400 percent in developing countries. See Sterns Economics of Climate Change, esp. chaps. 910.
14.See, for example, R. Lane, The Loss of Happiness in Market Democracies (New Haven:
Yale University Press, 2000), esp. chap. 4; R. Layard, HappinessHas Social Science a Clue?
(London: Centre for Economic Performance, LSE, 2003); and A. Offer, The Challenge of Affluence (Oxford: Oxford University Press, 2006), esp. chap. 2.
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need and capability created by, for example, a societys physical environment. Our question is to find a fair way of allocating responsibilities that
will get us to that final position. The equal-costs principle answers that
question. It does not assume that the status quo in terms of current emission levels is somehow sacrosanctas we have seen, it may require some
societies to make significant cuts in those levels. What it says to the peoples of the world is something like this: Global warming is a problem that
is likely to have very serious effects for all of us unless we take action now.
The action that is required involves some sacrifice, and all those who can
contribute without harm to their vital interests should do so on an equal
basis. Some will need to do more than others physically, but the sacrifice,
in terms of income or consumption forgone, should be the same for all.
After all this has been said, it may still be felt that it is somehow fair for
the richest states to make the biggest contribution to combating global
warming, and some proposals follow precisely this logic by, for example,
allocating the costs of change according to per capita GDP, or more radically still, according to a measure that also takes account of the degree of
income inequality within each society, with unequal societies paying proportionately more.16 (The thought behind this more radical proposal is
that some costs should be made to fall on rich individuals in poor societies.) I believe that such proposals overshoot the mark by trying to advance
a wider egalitarian agenda under the guise of a mechanism for tackling
global warming.17 They will be resisted by societies that feel that they have
collectively earned their present levels of GDP and do not see why they
should bear more costs per capita simply on account of their relative economic success. No one can object in this way to the equal-sacrifice principle as applied to nonpoor societies, nor, unless they are indifferent to
global poverty, can they object to the companion idea that endemically
poor societies should be allowed to increase their emissions where this
is essential for their economic development. Given that the aim of the
16.See, for example, P. Baer, T. Athanasiou, and S. Kartha, The Right to Development in
a Climate Constrained World: The Greenhouse Development Rights Framework, available
online at http://www.ecoequity.org/GDRs. The authors of this document advocate an overall
approach to burden sharing that combines historic responsibility with capacity, but their definition of capacity modifies national per capita income with a domestic income-inequality
measure.
17. For the argument that redistribution through greenhouse gas cuts is most unlikely to
be the best way to help poor people or poor nations, see E. Posner and C. Sunstein, Climate
Change Justice, a working paper available at http://www.law.uchicago.edu/Lawecon/index.
html.
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mean level of compliance across all states. What does fairness require
them to do?18
Consider option 2 first. This says that in situations of partial compliance, those who are able to do so should take up the slack. Assume here
that although further cuts in greenhouse-gas emissions would be costly,
they would not have deeply damaging effects on a society whose members
are already comfortably above the poverty line. What are the arguments
against doing so? First, that it is simply unfair to ask one party to do more
than their share of what is recognized to be a common taskin this case,
cutting gas emissions to an agreed-upon overall total. Particularly if the
agreement is based on the equal sharing of costs, as I have proposed, there
is no reason for one party to bear greater costs simply because others refuse
to carry their own fair share. Second, if one or more states show a willingness to take up the slack in this way, this creates a perverse incentive for
other states, already in default, to do less still by way of compliance.
These arguments seem sufficient to me to rule out option 2, in general.
An exception might occur if it became clear that the world was rapidly
approaching a crucial tipping point such that unless further cuts in gas
emissions were made quickly, an environmental disaster would follow.
Under these circumstances, fairness across nations might be outweighed
by a simple calculation of consequences, or as it might be claimed justice
between those responsible for causing global warming and those who
would be its victims if the disaster occurred. Whether we might be in such
a situation today is deeply contested. But unless we are, option 2 is not an
acceptable way of assigning additional responsibilities.
What then about option 3, namely, that what fairness requires is only
that we should do as much as others, on average, are doing, even though
this is less than is needed to solve the problem? The argument in its favor
is obviously that it preserves horizontal equity between societies and their
members: the per capita costs of adjustment are being equalized, or at least
approximately so.19 But again there are two arguments against. The first
is that acting on this principle is liable to provoke a race to the bottom. If
18. This is a particular instance of the more general question of what fairness requires in
circumstances of partial compliance, which I tackle at greater length in Taking Up the Slack?
Responsibility and Justice in Situations of Partial Compliance, in Justice and Responsibility,
edited by C. Knight and Z. Stemplowska (Oxford: Oxford University Press, forthcoming).
See also L. Murphy, Moral Demands in Nonideal Theory (New York: Oxford University Press,
2000).
19. This would be so if most societies are doing, say, about half of what the agreement
requires them to do. The argument is less strong if compliance rates vary widely.
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change agreement has the effect of bringing other reluctant parties into
the agreement, this might be justified. So might a strategy of conditional
cooperation whereby country A cuts its emissions somewhat but not by
the full extent required, waits for country B to reciprocate, and then cuts
its emissions further. Whether such tactics are justifiable depends on the
case. The underlying point, however, is that if they fail, full compliance is
what global justice requires.
The second rider is that if we compare the stated positions of the
United States and China as I described them earlier, they are different in
one important respect. The United States, a rich developed society and a
major emitter of greenhouse gases, intends apparently to make its compliance with a new international agreement on climate change conditional
on the participation of developing countries, and this I have suggested is
indefensible unless it is simply a tactical move to bring China and India to
the negotiating table. China, by contrast, is a leading member of the group
of countries for whom some increase in greenhouse-gas emissions can be
justified in terms of tackling poverty, and whose responsibility therefore
is primarily to minimize the increase by using suitable technology wherever possible. But if China is asked to adopt less polluting but more costly
forms of energy generation as part of an overall greenhouse-gas package,
it may need to receive technology transfers and maybe other financial adjustments, in trade agreements and so forth, if the poverty target is to be
achieved. It is no part of my remit to say what it is reasonable for China
to ask for in this area and what it is not. The general implication, however,
is that although China should be willing to accept firm emission targets
as part of an international agreement, it is reasonable for the Chinese
government to make complying with those targets conditional on receiving the material assistance specified in the agreement. Conditionality of
this kind is very different from unwillingness to enter an agreement at all
unless all other countries do likewise.
My aim in these two essays has been to reflect on the normative questions
raised by climate change and our collective responsibility to combat it.
This seems to me an area in which political philosophy is still lagging far
behind both physical science and economics. That is, we have a reasonably
good understanding of both the physical causes and the consequences of
global warming; we also have some good economic models of the policies
we might use to mitigate it. If we put those two sciences together, we can
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readily reach the conclusion that the problem of global warming is soluble,
in principle. We know what needs to be done to keep atmospheric concentrations of carbon dioxide and other greenhouse gases at acceptable levels, within the range 450550 parts per million of CO2, which observers
would regard as the highest we can allow without serious damage to our
planet. We also know that this outcome can be achieved without significant sacrifice to other goals, especially the economic development needed
to overcome world poverty. But the solution requires coordination among
independent nation-states that guard their independence and sovereignty
jealously, and therein lies the real obstacle. Unless we can agree on some
fair way of dividing up the responsibility, no one will be willing to take the
necessary steps. Justice is supposed to be the special subject of moral and
political philosophers, and what I have been attempting in these essays is
to bring that idea to bear on this most important of contemporary issues.
Notes
These two essays are based on the Tanner Lectures that I gave at Tsinghua University, Beijing, on March 2425, 2008. I should like to thank my
commentators on that occasionDaniel Bell, Joseph Chan, Jiwei Ci, and
Dan Guttmanfor their helpful suggestions, some of which have been
incorporated into this revision. I am also grateful to the Hans-SigristStiftung for awarding me a visiting fellowship at the Karman Center for
Advanced Study in the Humanities, University of Bern, which allowed
me to do further work on the text, and especially to Lukas Meyer for arranging this attachment. The Bern-Zurich Working Group on the Environment subjected an earlier draft to long and searching, but very fruitful,
criticism. Finally, I should like to thank Gillian Brock, Simon Caney, and
Dominic Roser, all better informed than I am on climate change issues, for
their help.
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