Climate Change

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Climate Change
Summary and Keywords
Understanding the complex set of processes collected under the heading of climate change
represents a considerable scientific challenge. But it also raises important challenges for our
best moral theories. For instance, in assessing the risks that climate change poses, we face
profound questions about how we ought to weigh the respective harms it may inflict on
current and on future generations, and on humans and other species. We face, in addition,
difficult questions about how to act in conditions of uncertainty, in which at least some of the
consequences of climate change – and of various human interventions to adapt to or mitigate
it – are difficult to predict fully (Gardiner, 2006). Even if we agree that mitigating climate
change is morally required, furthermore, there is room for disagreement about the precise
extent to which it ought to be mitigated (insofar as there is room for underlying disagreement
about the level of temperature rises which are morally permissible). Finally, once we
determine which actions we ought to take to reduce or avoid climate change, we face the
normative question of who ought to bear the costs of those actions, as well as the costs
associated with any climate change which nevertheless comes to pass. The primary focus of
this article will be upon this final issue. On the assumption that limiting climate change is
morally required, our mitigation efforts are likely to prove costly for some if not all of us.
Moreover, even if we mitigate now, some people will incur losses as a result of greenhouse
gas emissions to date. We therefore require guidance on exactly how, from the point of view
of justice, the associated burdens ought to be shared.
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Keywords: Climate change; mitigation; adaptation; compensation; global justice;
intergenerational justice
Introduction
Processes of climatic change have been a constant throughout the world’s history. In many
cases humans have adapted well to localised changes in climate, and even flourished in their
wake. In other cases they have failed to do so, and the communities concerned have faced a
choice between migration and extinction. Climatic change and desertification probably drove
the exodus of humans from Africa around 100,000 years ago, after which they successfully
colonised the Asian and then European continents – and in that sense most of the world’s
population are ultimately descended from ‘climate refugees.’ History is replete with examples
of communities perishing, or moving, because of the failure of crops, the extinction of prey,
or the collapse of water supplies attendant on various climatic changes.
The contemporary challenge of climate change might be thought to be distinctive in
several ways, however. First, the effects of the climate change we now face will not be
localised, but rather will be global in scope. People and wider ecosystems everywhere in the
world will be affected. Second, the consequences of global climate change, if unabated, will
occur on an unprecedented scale. Mass extinctions and loss of habitat are among the likely
consequences. Human communities in many parts of the world will find it difficult or costly
to adapt to the threats which the changing climate generates. Millions of people who are
already among the world’s worst-off will find their very livelihoods threatened (IPCC, 2014).
But though they will be hardest hit, the impact of climate change will not only be felt by the
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world’s poor. Among the consequences could be surges in mass migration, in political
instability, and in epidemics of infectious diseases, the impact of which would in turn be felt
by the more privileged. Third – by contrast to many of the climatic changes which our
ancestors faced, which were often experienced as though they were acts of God – our
understanding of, and even control over, the climatic challenges we face appears to be rather
good. Our own actions will exert a significant influence upon the degree and kind of climate
change that is likely to occur. Catastrophic climate change would be to a large extent a
human-made disaster – in the dual sense that humans both caused, and could have prevented
it.
These facts make questions about the mitigation of climate change highly salient
politically. Climate change is a complex phenomenon, but its principal mechanism involves
increases in the ‘radiative forcing’ of the world’s atmosphere. As concentrations of so-called
‘greenhouse gases’ in the atmosphere increase, its tendency to trap energy from the sun
increases in turn, paving the way for rises in global average temperature. Mitigation, by
contrast, refers to actions taken to reduce any such increases in the atmosphere’s radiative
forcing. Various mitigation measures are available to us. The lion’s share of public attention
has been garnered by proposals to constrain the combustion of fossil fuels, since that
combustion releases very large quantities of greenhouse gases into the atmosphere. But
additional mitigation measures may be available besides reductions in fossil fuel use.
Practices of deforestation or forest degradation, for instance, are also associated with the
release of substantial quantities of greenhouse gases, and as such measures to reduce
deforestation – or indeed to reforest land – could play an important role in global mitigation
efforts. What is important here is that forests act as ‘carbon sinks,’ removing carbon from the
atmosphere and storing it safely. Indeed scientists have investigated several other methods of
sequestering greenhouse gases besides reforestation. Various proposals for ‘carbon capture
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and storage’ have been made, including plans to store carbon dioxide under the seabed. Such
proposals are probably some way from fruition, however. Likewise scientists have
investigated many proposals – some of them quite outlandish – to increase the reflectiveness
or ‘albedo’ of our planet, in order that less energy is absorbed from the sun. The likely
effectiveness, and risks associated with, these and other ‘geoengineering’ schemes are the
subject of controversy (Gardiner, 2010). Indeed it is also a subject of controversy whether all
such schemes qualify as mitigation measures - although insofar as they aim to reduce or
avoid increases to the radiative forcing of the world’s atmosphere, they certainly bear
comparison with measures to reforest or to cut back greenhouse gas emissions.
The mitigation of climate change is, importantly, a matter of degree. Some measure of
climate change is an ever-present feature of our world, and may not be objectionable. The
continued presence of humans on the planet is after all evidence of our adaptability, and some
changes in climate may even be perceived as positive. But climatic change can be so severe,
and so rapid, that the ability of humans and ecosystems to safely adapt to it is compromised.
Calls for concerted global action are driven by the fear that unabated fossil fuel consumption
and deforestation will engender temperature rises without parallel in human history. Indeed
we already appear to be committed to potentially damaging rises in global average
temperature, as a result of the emissions-intensive activities which have accompanied
industrialisation in many countries. Efforts at mitigation, therefore, are not efforts to avoid
any climatic change, but rather to prevent temperature rises exceeding some level which
would impose what we consider to be unacceptable costs on human beings or on wider
ecosystems. Quite where that level falls will depend upon the impacts we are prepared to
tolerate. For instance, some advocacy groups have argued that average temperature rises
exceeding 1.5°C ought to be avoided. Others have suggested that our target ought to be a
warming limit of 2°C (for discussion see Moellendorf, 2014: 23-4).
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The precise temperature target which is chosen will in turn influence the costliness of
overall mitigation efforts: restricting temperature rises to 1.5°C will be more costly, other
things being equal, than restricting it to 2°C. Notably, the available ‘carbon budget’ – and
hence the proportion of the world’s fossil fuel reserves which can still safely be burned – will
be smaller if we are working towards a lower temperature target. The nature of the mitigation
policies we choose will also influence overall costs. It might be the case, for instance, that
forest protection and enhancement is more expensive than actions to make transport and
housing more energy-efficient. Or the reverse could be true. The timing of mitigation may
also influence its costliness. Conceivably, it might be cheaper overall to pursue mitigation
policies now, and more expensive to pursue them later. Or, again conceivably, the reverse
could be true. That is an empirical question. Other things being equal, it makes moral sense to
pursue mitigation efforts when it is least costly to do so. But note that in principle questions
about the timing of mitigation and about the allocation of mitigation burdens can be
separated. Some believe that future generations will be better off than us, and hence better
able to bear mitigation burdens. It might be, therefore, that whereas we ought to mitigate
now, we can permissibly pass the costs of our action on to future generations (see below).
If we fail to mitigate – and if dangerous climate change comes to pass – then various
harms will ensue. We would then face the question of who ought to bear the associated
losses. For instance, if we believe that many of those who fall victim to the gravest impacts
could not be held responsible for their own losses, some other principled basis must be found
for allocating costs. This is the issue of the fair allocation of the burdens of compensation. At
the same time, there are questions about who ought to foot the bill when people are required
to adjust their lives to a changed environment. Here we face the issue of the proper allocation
of the burdens of adaptation. The most extreme forms of adaptation will involve people –
such as the inhabitants of small island states – losing their homes entirely and relocating to
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other places in the world. Indeed we likely face these two questions about the costs of
compensation and adaptation already. Even if the world's states committed now to doing their
utmost to mitigating climate change, some losses are already with us, and some have already
been forced to move. Our focus in this article will be upon the question of who ought to bear
these burdens. I will use the term ‘climate burdens’ as a shorthand for the costs of mitigation,
adaptation and compensation.
Climate Change and Intergenerational Justice
If dangerous climate change comes to pass, many people alive now will be hard-hit. But the
most significant harms will likely be felt by future generations. Once in the atmosphere, some
greenhouse gases will continue to influence global temperatures for many generations to
come (and perhaps hundreds of generations). Likewise, major extinctions or the widespread
destruction of arable land would affect the prospects for wellbeing of future people as well as
those currently living. If so, we might believe that one reason – and perhaps the most
important reason – why we ought to mitigate climate change arises from a proper concern
with the rights or interests of people who are not yet born.
But the deference we ought to show for the rights of future people is a matter of
controversy within political philosophy. For one thing, on some theories of justice future
people do not (yet) have rights, and therefore cannot have rights against us regarding our
actions. If injustice is a matter of rights-violations, it might then be thought that there can be
no question of us treating future people justly or unjustly (Steiner, 1994). For another thing, it
is controversial in what way the actions of current generations can be said to harm people
living in future generations when the specific identities of those people may not yet be fixed.
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A person’s specific identity (that is, which person they will become) is not determined until
they are conceived, and a variety of actions might influence the timing of conception, and
hence the identity of the resulting people. But if the decisions of current generations – to
build power stations, to drive energy-inefficient cars, and so on – can be expected to affect
which future people come to live, we face a quandary. For it may be that a future person
cannot claim to have been harmed by our actions if it is also the case that they would not
have existed but for those actions (Parfit, 1984). If it is compelling, the so-called Non-
Identity Problem could have serious implications for theorising about climate justice. Many
people believe that our impacts upon the global climate constitute an injustice, given that they
will predictably lead future people to become worse off than they would otherwise have been,
or worse off than we are. But if our non-performance of those actions would have the
consequence that the supposed victims of the harm in question would not have existed at all,
it is not obvious that we should consider them to have been harmed by those actions. One
way or another, those convinced that we do have stringent duties of justice towards future
people must find some way of reconciling their positions with the Non-Identity Problem (see
e.g. Meyer, 2003). Alternatively, they might attempt to motivate environmental restraint
without making any claims about our obligations to future people – for instance, by arguing
that we owe it to currently-existing generations to reduce our contributions to environmental
degradation or to climate change (Mazor, 2010; Gheaus, 2016).
Even if we determine that principles of justice do constrain our impacts upon future
generations, it remains to be seen what the character of those principles should be. We might,
for instance, embrace sufficientarian or minimalist views which claim that the concerns of
justice are exhausted once everyone’s basic needs or basic rights are met, or alternatively
egalitarian views which show a concern for people's comparative wellbeing (Armstrong,
2012). On one sufficientarian (or minimalist) view, we ought to leave future people with the
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ability to maintain minimally effective social and political institutions capable of delivering
on the rights of members, and this might imply some constraint on our environmental
practices. But such a constraint would stop short of demanding that we leave our descendants
with a standard of living equally as good as ours (Rawls, 1999). Some scholars have
suggested that a sufficientarian view of intergenerational justice enjoys the best prospects of
navigating the Non-Identity Problem, precisely because it specifies a threshold of wellbeing
against which harms can be judged (Meyer and Roser, 2009). On an egalitarian view, by
contrast, just as it would be unjust for someone’s life to go worse simply because of the
country in which they were born, so too would it be unjust for someone to face worse
prospects simply because they were born later than us (Lippert-Rasmussen, 2016: 156-61).
People's prospects for wellbeing ought not to hinge on where in time they live. Such a view
would likely impose significantly stronger constraints upon our environmental practices.
Though egalitarian views are in one respect more demanding, both sufficientarian and
egalitarian views on intergenerational justice have potentially revisionist implications when it
comes to our current practices. They would likely have us condemn, for instance, some of the
most influential ways of assessing the intergenerational burdens of climate change.
Economists have typically operated under a utilitarian moral framework, according to which
the goal of public policy is to maximise utility or wellbeing. But when applied to questions of
intergenerational justice, utilitarianism can generate unpalatable or puzzling consequences. It
might imply, for instance, that each generation ought to save as much as possible – even at
the risk of penury – if it appeared likely that an indefinite number of future generations might
thereby benefit. In order to avoid such a conclusion, economists have often argued that we
ought to be able to ‘discount’ the wellbeing of future people when engaging in the cost-
benefit analysis of different policies (such as mitigation policies). Indeed economists’
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(discounted) calculations of the likely costs of mitigation or of the failure to mitigate have
often resonated with policy-makers.
Egalitarians and minimalists will find reasons for suspicion about the utilitarian
assumption that we ought to maximise wellbeing even at the costs of leaving some
generations disadvantaged, or in poverty, and in that sense the purported solution – of
discounting the interests of future generations – does not in any case hold the initial appeal
that it does for utilitarians. Nevertheless, they have also expressed concern about some of the
forms of intergenerational discounting which economists have defended. Whilst it is not clear
that all forms of discounting are indefensible from an egalitarian point of view, for instance,
some of them do appear highly problematic from an egalitarian perspective, and perhaps even
from the perspective of views which aim merely to safeguard the most basic rights of future
people. So-called ‘pure time preference,’ in particular, discounts wellbeing simply insofar as
it occurs at a later point in time, with the result that it becomes permissible to avoid smaller
losses to those currently living even at the cost of causing greater losses to those who will
come later. If the gulf in time between us and the future people in question becomes great
enough, the rate at which we can discount the interests of the latter can then be very
substantial indeed, potentially rendering actions which would jeopardise even the most basic
interests of future people permissible. For some political philosophers, however, pure time
discounting is ‘arbitrary and even discriminatory’ (Moellendorf, 2015: 175). If there is ‘no
reason to attribute fundamental moral importance to someone’s location in time’ (Caney,
2014: 4), such forms of discounting ought to be rejected. The egalitarian suspicion is that
such forms of discounting are an unattractive fix for a utilitarian moral view which itself
ought to be rejected (Rawls 1999: 262).
Theories of intergenerational justice are relevant not only to the question of the harms we
can permissibly impose on future people, but also to the question of how any mitigation,
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adaptation and compensation burdens ought to be allocated between the generations. Now, it
might be thought obvious that, since dangerous climate change is an imminent and potentially
irreversible threat, the burden of preventing it, in particular, must be borne by those now
living – lest the opportunity to mitigate be lost. But we have already noted that the duty to
mitigate, and the duty to bear the costs of mitigation, could potentially be allocated
separately. Some have argued that, whilst current generations ought to engage in mitigation,
they need not necessarily bear the burdens of doing so. If there are ways in which we can
pass the burdens on to future generations, ‘deferring the costs’ might be possible even if
‘deferring action’ is not (Caney, 2014: 332-8). By way of illustration, current generations
might mitigate now, but recoup the costs of doing so by cutting back their spending on long-
term transport infrastructure, or by building less durable houses. If they did so, future
generations – though they did not pay for mitigation in any literal sense – would end up
bearing an equivalent cost.
Parallel points might be made, in principle, with regards to adaptation and compensation
burdens. Though adaptions must be made by those affected by climate change, for instance, it
is conceivable that the costs of such adaptations could be passed along to future generations.
One view here is that passing costs along to future generations might be unfair from the point
of view of intergenerational justice, but defensible all things considered given that tackling
climate change is such an urgent priority. In particular, whilst sharing the costs of mitigation
fairly between generations would be preferable, it might be ‘politically more effective’ to
separate the aims of mitigation and of promoting intergenerational justice more broadly
(Broome, 2012: 155). Alternatively, we might argue that passing climate burdens down to our
descendants need not involve any injustice in the first place, if our descendants are otherwise
likely to be much better off than us (Rendall, 2011; Caney, 2014).
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Climate Change and Global Justice
Climate change is a global problem, and the arguments we discuss in this article have been
made by scholars who believe we can have grounds of justice for objecting to the impacts
unmitigated climate change might have upon distant others. As such these approaches are at
least weakly ‘cosmopolitan.’ They assume, that is, that concerns about distributive justice and
injustice do not stop short at national borders. They claim, rather, that talk of global justice
and injustice is intelligible, and that our actions should be constrained by at least some
principles of global justice (though they may disagree on the character of the relevant
principles). For this reason, our question about how climate burdens ought to be distributed
globally is agreed to be an intelligible one.
Nevertheless, the relationship between concerns of climate justice and broader
concerns of global justice is contested. A key question is whether our preferred ‘solution’ to
our question about mitigation, adaptation and compensation costs should advance global
justice more generally. For instance, if our conception of global justice is egalitarian in
nature, how far should our position on the allocation of climate burdens be influenced by a
concern to reduce inequality in general? We can imagine at least three positions in response
to this question. A first view would hold that we should seize the opportunity offered by
climate change to ease global injustices in general (Gosseries, 2014: 101; see also Caney,
2012). A second view would hold that our allocation of climate burdens should not make
global injustice worse. For instance, it might be argued that whatever allocation of climate
burdens we choose, we should not make it harder for the very poor to escape from their
poverty (Miller, 2008; Moellendorf, 2014). A third view would be that the allocation of
burdens should not be influenced by wider concerns about global injustice. Miller (2008:
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150), for instance, has argued that we should not turn climate policy into an occasion for
general egalitarian redistribution (though, as we have just observed, he also argues that our
division of burdens should not exacerbate global poverty). A similar view is defended by
Posner and Weisbach (2010) on the basis of a concern for feasibility. Specifically, they argue
that any politically feasible climate agreement will necessarily be one which brackets
questions about wider economic injustice, and disdains proposals for redistribution. It is
contentious, however, whether a concern for feasibility speaks in favour of bracketing wider
distributive questions. On some rival views, it might be that eliciting the cooperation of
developing countries in a global climate agreement will demand that we address background
injustices (Moellendorf, 2014; Caney, 2012).
Allocating Climate Burdens
In what follows I will inspect three well-known principles which might inform the allocation
of climate burdens. Before we begin, however, it will be useful to bear two points in mind.
First, we face a question about who the relevant bearers of climate burdens are. Some
discussions of climate justice assume that our task is to properly share the burdens carried by
particular nation-states. But ‘cosmopolitan’ views on justice hold that it is the wellbeing of
individuals that fundamentally matters from the point of view of justice. If so, then our
concern should be that burdens are properly shared between individuals. It might be, to be
sure, that states (rather than individuals) are the entities with the power to make and enforce
any deal to stabilise the global climate. And perhaps the nature of international law, and of
negotiations between states, ensures that a global climate agreement would allocate specific
burdens to states in the first instance. But even if it did, for the cosmopolitan we would then
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need to find some way of making sure that the individuals who ought to bear the greatest
burdens ended up shouldering them. For instance, if we believed that the rich ought to bear
the greatest climate burdens, ensuring that richer countries bore greater burdens would not be
enough. We would also have to ensure that richer individuals in rich countries – and,
potentially, richer individuals in developing countries too – bore greater burdens than their
poorer compatriots. Similarly, if we believed that duties to bear climate burdens should in
some way track emission levels, government policies that placed greater burdens on the
shoulders of high-emitters within a particular country, rather than low-emitters, would be
required. If so, we ought not to be content with a situation in which the distribution of
burdens within countries was left entirely at the discretion of their governments (cf Miller,
2008: 121-2).
Second, we should be clear about what qualifies as a climate burden. In the case of
mitigation burdens, we should resist the temptation to simply equate those burdens with cuts
in greenhouse gas emissions. Discussions of mitigation are sometimes dominated by the
question of who ought to cut their emissions by how much – or, to put it the other way
around, who has the right to use up what proportion of the remaining carbon budget. But our
question about mitigation burdens does not reduce to this narrower question about emissions
rights. Whilst it is true that globally speaking mitigation will almost certainly require cuts in
total emissions (that is, unless scientists are very wrong about the limited prospects for
carbon capture and storage or various geoengineering schemes, for instance), it is not
necessarily the case that each individual can only contribute to mitigation by cutting her
emissions. There could be a variety of ways in which any given individual can advance the
goal of mitigation (and carry burdens in the process). For instance, it might be that the best
way any given individual can contribute to the collective mitigation effort is by working to
develop a new clean technology, by securing greater investment in public transport, by
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protecting or enhancing a forest, or by lobbying politicians to make serious commitments to
binding emissions cuts. Aïsha, a hugely persuasive activist, might make a significant overall
contribution speaking at public events even if this means she must drive, or fly, to those
events.
But if there are a variety of ways in which individuals can bear the burdens of mitigation,
there need not be any tight connection between the allocation of mitigation burdens and the
allocation of emissions rights. Neither need it be the case that our hypothetical individual can
only contribute to mitigation by making changes to her own consumption behaviour more
broadly. An individual in one country might in principle bear her proper share of the
mitigation burden by helping to fund the roll-out of clean technology in another country.
Alternatively she might do so by protecting or extending – or funding the protection or
extension of - forests on the other side of the world. Unless we have some special reason for
believing that we ought to each cut our emissions regardless of the other impacts we have on
the climate, all of these activities might potentially count as carrying one’s fair share of the
burden (see Caney, 2012). Likewise, it is perfectly conceivable that one individual might bear
costs by paying another individual to restrict her emissions. This, in essence, is what carbon-
trading schemes allow, unless we have some decisive reason for rejecting such schemes
(Gosseries 2015; Caney 2010b). Indeed this separability of emissions cuts and mitigation
burdens should not come as a surprise. After all, we have already established that in principle
future generations might bear the costs of mitigation efforts (including emissions cuts) made
by current generations. In that case future generations would, in a sense, be paying us to cut
our emissions. Mitigation burdens cannot be reduced, then, to duties to cut one’s emissions.
The same goes a fortiori for adaptation and compensation burdens, which in principle might
be discharged in a variety of ways. Indeed, though I have concentrated on mitigation in this
section, there is no obvious reason why mitigation burdens ought to be allocated separately
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from adaptation or compensation burdens. If not, an individual might discharge her fair share
of climate burdens by helping others to adapt, or by reducing losses attendant on climate
change, even if she does not contribute to the goal of mitigation at all.
Contribution
At its broadest, the so-called contributor pays principle stipulates that those who are
responsible for bringing some harm (or threat thereof) into being should carry any costs that
it generates. If it was applied to the burdens of mitigation, adaptation and compensation, the
principle would place greater burdens on the shoulders of those whose actions have caused
greater quantities of greenhouse gases to be emitted. It is not, to be sure, the case that we can
trace any particular instance of harm back to any specific individuals’ (or even state’s)
emissions (Page, 2011: 416). When we emit, we simply add to the global concentration of
greenhouse gases, and increase the risks of harms coming to pass at some point. Still, the
quantity of harms which ensue will presumably track emissions, and individuals, we might
stipulate, are responsible for those emissions, and hence for contributions to the net sum of
harms.
The idea that we ought to bear the costs of making good any harms we have engendered
enjoys considerable intuitive appeal. The suggestion that farmers who allow pesticides to leak
into rivers ought to pay for the rectification of the environmental damage that ensues, for
instance, exerts an immediate pull on our moral sentiments. In common parlance, the thought
runs something along the lines of ‘you broke it, you fix it.’ In the words of one defender, the
contributor pays principle ‘acknowledges that we are agents who make an impact on our
surroundings, and who should be held responsible for that impact’ (Miller, 2008: 126).
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It is not clear, though, that the principle can govern the allocation of all climate burdens.
Climate change is not caused solely by the greenhouse gases which are being emitted now,
but by gases building up in the atmosphere across several generations. Some of these
emissions will not have been caused by humans at all. And some will have been caused by
people who are now dead. Obliging past generations to bear any additional climate burdens
is, however, impossible (though we might still believe that, if we could do so, we should).
Some have, to be sure, thought that the contemporary descendants of high-emitters ought to
bear a greater share of climate burdens (e.g. Shue, 2014: 186; Miller, 2008: 129). But if there
are good arguments to that effect, they cannot be grounded upon the contribution that current
generations have made to bringing those historical emissions about. Rather they must rest on
some other idea, such as the claim that those who have benefited from past generations’
emissions ought to bear greater burdens. Such an argument would, in that case, rest not on the
contributor pays principle, but on the ‘beneficiary pays principle’ (see below).
Even when it is the currently-living who have caused specific emissions, moreover, it is
not beyond dispute that they ought to bear greater climate burdens as a result. Some theorists
have certainly defended a ‘strict liability’ view, according to which a causal contribution to
emissions is sufficient to justify greater burdens. But a strict liability view might be resisted
on several grounds. One concerns an agent’s knowledge of the likely consequences of her
actions. It may be that in some cases those who emitted were excusably ignorant of the
contribution they were making to climate change. For instance, some emissions may have
occurred at a time when processes of climate change were not well understood. Even if we
believe that the risks of climate change have been familiar for, say, the past thirty years or so,
it is not obvious why those who emitted before that time ought to bear greater burdens
(Miller, 2008; Singer, 2002).
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A second ground for scepticism about the strict liability view concerns the presence or
absence of alternatives. Perhaps in some cases people who engaged in activities which
generated emissions did not possess alternative options at all. Or perhaps the alternatives they
possessed would have been unduly costly to pursue. In such cases, it might be remiss to
require agents to bear greater burdens. Imagine, for instance, that for some people emitting
substantial quantities of greenhouse gases is the only available means of escaping severe
poverty. Saddling those people with the task of reducing their emissions might only serve to
keep them in poverty. To the contrary, on some views the very poor should not be required to
cut their emissions, at least until the wealthy have made available to them affordable
alternative sources of energy (Shue, 2014). But if the poor ought to be allowed to emit in the
meantime, lest they remain in poverty, then requiring them to bear climate burdens as a result
of their emissions seems to be ruled out too.
Indeed we can imagine still other ways in which the conclusion of strict liability could be
resisted. Some people might have caused emissions in the pursuit of morally valuable
endeavours – some of which may even have been morally required, on balance, even though
they generated those emissions. An aid agency which drove trucks full of aid to the poor of
the world, for instance, will have generated emissions in the process. But we might believe
that those emissions ought to be ‘forgiven,’ given the urgency of the need to which the
agency was responding (indeed we might reach the same conclusion in the case of Aïsha, our
imaginary climate activist from earlier in the article). In principle, then, some of the
emissions made by the well-off in our world might have been made in pursuit of activities
which were morally valuable all-things-considered; and if so perhaps they should not lead to
greater climate burdens falling on their shoulders either. Now, for the rich to claim that a
substantial portion of their emissions were incurred in the process of delivering benefits to the
worst-off in the world would almost certainly stretch credulity (Shue, 2014: 184). But in
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some cases the claim could be true, and in those cases causal (even knowing) contributions to
climate change might not justify greater climate burdens. Whilst the contributor pays
principle enjoys considerable appeal, it also appears to have limited scope.
Ability
The ability to pay principle also enjoys substantial intuitive appeal. Such a principle would
require individuals to make sacrifices in line with their underlying levels of advantage, so that
the better-off made greater contributions than the worse-off. In the case of climate change, we
might argue for instance that wealthy people can more easily carry climate burdens than very
poor people, whilst still being able to lead lives of comparative luxury. Whereas the
contributor pays principle is backward-looking, in the sense that it requires burdens to track
(some) emissions to date, the ability to pay principle allocates burdens on the basis of the
present or future capacity of agents to absorb those burdens.
As it stands, the principle requires further specification. Notably, adherents of the
principle need to specify a metric for the capacity to bear burdens. For instance, individuals
might be thought to stand in line to bear greater burdens because of their greater income, or
their possession of greater resources in general, because of their higher functioning as
measured for instance by the Human Development Index, or because of their greater overall
welfare. Adherents also need to specify in more detail what it means for burdens to track
ability to pay. For example, we might embrace a simple linear rate of contribution, according
to which those who are better off are required to sacrifice more, and absolute sacrifices rise in
strict relation to rising levels of advantage. Or we might favour a progressive rate of
contribution, according to which the proportion of their advantage which agents are required
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to sacrifice rises in line with their overall level of advantage (Shue, 2014: 187). In addition,
the ability to pay principle might be modified in various ways. One variant is defended by
Simon Caney (2010a). On his view, those with greater ability ought to bear greater mitigation
burdens, other things being equal. But those whose resources have arisen from the unjust past
emissions of previous generations also ought, other things being equal, to bear greater
burdens, on the basis that their claim to those resources is weaker. One question here is why
we would not generalise such a principle so that those who possess resources derived from
all kinds of injustice ought to pay more, rather than those whose resources are derived from
climate injustices alone. Another is whether there is anything morally distinctive about
possessing resources derived from past injustice as opposed to, say, one's own good brute
luck. But in principle we could construct a hybrid principle which tracked not ability
simpliciter, but some combination of both pure capacity and the ‘taintedness’ (Butt 2007) or
otherwise of particular advantages.
The ability to pay principle has been considered particularly attractive by egalitarians,
who want to ensure that the distribution of climate burdens either does not exacerbate, or
indeed actually reduces, broader global inequalities. But we can also envisage limited
variants of the principle, which might appeal to those who hold sufficientarian views on
justice. For instance, some accounts stipulate that the worst-off ought not to bear any of the
costs of dealing with climate burdens. Some other principle or set of principle would then
need to be introduced to determine sacrifices above the relevant threshold of wellbeing. Such
an account would not allocate burdens strictly on the basis of ability to pay, but it would
exempt some actors from bearing burdens on the basis of their inability to pay. The rationale
for such a proposal would presumably be that, even if mitigation, adaptation and
compensation are urgent priorities, the poor of the world have a still more pressing priority:
escaping from poverty. It would therefore be unfair to ask the global poor to divert their
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efforts, or their resources, to tackling a problem which the rich of the world could easily solve
on their own (Moellendorf, 2015; Shue, 2014: 193).
On what basis, though, might we then allocate burdens above the relevant threshold? One
proposal is that whilst countries with endemic poverty should be excused from making any
sacrifices, above that threshold burdens ought to be shared equally. On David Miller’s
account, the ‘principle of equal sacrifice’ holds that (here, mitigation) burdens ought to be
‘allocated on an equal per capita basis among the members of the better-off societies’ (Miller,
2008: 146). Miller considers this principle a version of the idea ‘from each according to his
ability.’ But from the point of view of ability to pay, this proposal actually looks somewhat
counter-intuitive. For in requiring the same sacrifice (construed in terms of a reduction in per
capita income) from each person who sits above the poverty baseline, it is insensitive to the
comparative position of everyone above that baseline. It would require exactly equal
sacrifices from someone very considerably above the poverty line and someone living only
just above it. Indeed it would also require the same (that is, no) sacrifices from those just
below the threshold and those very far below it. Though it does track ability in one way (by
exempting those below the threshold from any sacrifice), the overall effect would depart
considerably from proposals based on ability to pay proper.
Still, some have found the ability to pay principle in itself unpersuasive, at least if it is
intended to serve as a comprehensive principle for regulating the allocation of climate
burdens. According to Page (2008, 2011), for instance, a deficiency of the ability to pay
principle is that it would require wealthy but low-emitting countries to bear precisely the
same burdens as countries which are equally wealthy but have become so only by emitting
large quantities of greenhouse gases. To provide a concrete example, an (income-linked)
ability to pay principle would place slightly higher burdens on the shoulders of contemporary
Australians vis-à-vis contemporary Germans. But the cumulative emissions attributable to
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many generations of Germans are more than three times greater than those attributable to
Australians (Page, 2011: 419). Requiring smaller sacrifices from contemporary Germans
compared to contemporary Australians would be an implausible conclusion, on Page’s view,
because the former are as well-off as they are in significant part because of the excessive
emissions of their ancestors. If we gave proper consideration to the ways in which currently
levels of advantage were derived, we might instead endorse the idea that the present-day
beneficiaries of disproportionately large past emissions ought to bear greater burdens. We
would be led to endorse, that is, the beneficiary pays principle.
Benefits
The so-called beneficiary pays principle requires people who have benefited from the
activities which have generated the problem of climate change to bear a greater share of the
burdens of dealing with it. Unlike the ability to pay principle (which, at least unmodified,
requires sacrifices to track capacity to bear burdens, regardless of how that capacity has
emerged), the beneficiary pays principle suggests burdens ought to track the ways in which
agents’ wealth or wellbeing has come about. It places normative weight, specifically, on
causal connections between the past emission of greenhouse gases and current levels of
advantage. Even among individuals with strictly equal capacity to bear burdens, an individual
whose wealth or wellbeing has derived (more) from excessive historical emissions stands in
line to bear (greater) burdens.
The beneficiary pays principle offers guidance potentially at odds with each of the
principles we have considered thus far. For instance, its implications might depart quite
radically from those of the ability to pay principle. An individual who becomes a billionaire
21

today as a result of inventing some new green technology, for instance, might be said to have
derived those financial benefits in a ‘clean’ fashion – and if so, would not stand in line to bear
any climate burdens as a result. The ability to pay principle, on the other hand, would
presumably require greater sacrifices of him simply because he is now very well-off.
The principle will also offer guidance contrary to that provided by the contributor pays
principle. Notably, those liable to bear burdens under the beneficiary pays principle need not
be considered morally responsible in any way for the emissions from which they have
benefited (Page, 2011: 421). The principle is therefore sometimes thought to have a wider
scope than the contributor pays principle. In another respect, however, its scope appears to be
narrower. For it seems that the contributor pays principle would require greater burdens to be
borne by people who are responsible for emissions even if they did not benefit from them; the
beneficiary pays principle, by contrast, would not (Page, 2011) – with the apparent
implication that those who (or whose ancestors) simply emit greenhouse gases to no good end
do not thereby incur greater climate burdens.
The beneficiary pays principle is perhaps the most controversial of the three principles we
have considered. Whereas contribution and ability are commonly taken to be relevant to the
allocation of climate burdens, some scholars deny that the beneficiary pays principle has any
relevance – or indeed any moral force - at all. A major strength of the principle, according to
its adherents, is that it needs to lean on no, or perhaps at best leans on only modest, claims
about causal responsibility for emissions. In order to justify placing greater burdens on her
shoulders, is enough to establish that an agent has benefited from past emissions, whether she
played any hand in generating them or not. But for its critics, this purported strength is in fact
a weakness. For why should those who benefit from others’ carbon-intensive activities stand
in line to bear greater burdens? The claim typically made by defenders of the principle is that
if our ancestors’ emissions were disproportionately large, then the economic growth which
22

resulted from them constitutes an unjust form of enrichment. If the benefits arising from that
growth now pass down to us, we may be morally obliged to relinquish them (Page, 2011;
Butt, 2007). It need not be the case, here, that we played any part in the perpetration of the
relevant injustices. Even if we did not, we may be strictly liable to give up the benefits arising
from those injustices (Page, 2008: 562).
But the key question is why the causal connection between perpetrators of injustice and
present beneficiaries is morally significant at all, if there is no causal responsibility on the
part of current generations (Huseby, 2015). Some would simply deny the claim that equally
well-off individuals ought to bear unequal burdens merely because one of them possesses
benefits which were initially generated (by others) through the perpetration of some injustice,
whereas the other does not. Indeed it might be argued that the beneficiary pays principle
offers guidance which is arbitrary. For instance, we might ask: why should it be those who
have (innocently) benefited from others’ unjust emissions who should bear greater climate
burdens, as opposed to those who have (innocently) benefited from other forms of injustice?
We might also ask: why should beneficiaries of unjust emissions disgorge resources so that
climate change can be dealt with, as opposed to other valuable goals, such as the alleviation
of poverty? It might be that the benefits which innocent beneficiaries of wrongdoing are
obliged to give up should be made available for advancing justice goals in general (see
Goodin 2014). If good answers cannot be provided to those questions, it may feed the
suspicion that the beneficiary pays principle has no intrinsic moral force, and that it appears
to provide reliable guidance in some cases only insofar as it leans on some other underlying
normative principle (Huseby, 2015; Lippert-Rasmussen, 2017).
23

Conclusion
In this article I have attempted to clarify the moral problem of the fair allocation of climate
burdens. When it comes to the moral principles to which we should turn in allocating those
burdens, we have considered three leading contenders. It might be thought, however, that the
latter discussion has been needlessly esoteric, especially in the face of such a huge and
pressing political problem. For is it not the case that arguments from contribution, ability to
pay, and benefits, all point in largely the same direction when it comes to allocating climate
burdens? In the real world the richest countries also tend to be high-emitters, after all; and
they also tend to have emitted (and benefited from emitting) disproportionate shares of
greenhouse gases in the past (Shue, 2014: 205; Singer, 2002: 26-7; see also Shue 2015).
Even if that is generally true, cases in which it is not true are easy to imagine, and we
need to know how to deal with them. It is far from inconceivable that a low-emitting state
could nevertheless become rich, for instance by selling natural resources. It is also perfectly
conceivable that, among two states with similar present standards of living, one may have
benefited from substantial historical emissions, whereas the other may have begun to emit
large quantities of greenhouse gases only relatively recently (this is precisely what the
Germany / Australia contrast appears to show). In such cases contribution, ability and
benefits may pull in different directions when it comes to assigning burdens. Indeed even if
they did not, it might be philosophically important to understand precisely on which basis
climate burdens ought to be allocated. Even if all three arguments seem to point in the right
direction, that is, it might turn out that one or two of them are false. If so, we should want to
know which argument is sound, and therefore doing the normative work in sustaining our
conclusions about climate burdens.
24

The arguments of the previous section appear to suggest that no one principle is
equipped to provide a comprehensive guide to the allocation of burdens. Insofar as people
have knowingly and avoidably emitted disproportionate quantities of greenhouse gases, it
will often make sense to require them to bear greater climate burdens. But some emissions
are non-anthropogenic, and others will have been generated in conditions under which, on
some plausible views, agents cannot or should not be held responsible. In such cases some
other principled basis must be found upon which to allocate burdens. A leading suggestion
here is that the ability to pay principle can step in when the contribution principle ceases to
apply (Caney, 2010a). Alternatively we might compose a framework by way of which
burdens tracked some weighted combination of both ability to pay and past emissions (Baer
et al, 2009). A further possibility would be to adopt a division of labour whereby, for instance,
some version of ability to pay governed the allocation of mitigation costs, and contribution
governed the allocation of adaptation costs (Miller, 2008: 151). But for such a solution to be
compelling, we would need some reason to think that mitigation and adaptation costs ought
to be allocated according to different criteria, and it is not immediately clear what such a
reason would be. Finally, some have thought that patterns of benefits arising from the
activities which have generated climate change possess independent moral significance –
significance, that is, which does not reduce to facts about either contribution or ability to bear
burdens. But it remains contested whether such facts about benefits possess such significance
in their own right. None of this dissensus suggests that climate change is anything other than
an urgent problem, which if left unmitigated would impose unacceptable harms on an
enormous scale. Neither should we downplay the important fact that the most plausible
principles for distributing climate burdens do point to a large extent in the same direction:
that inhabitants of wealthy countries ought to bear the lion’s share of climate burdens. But it
25

does suggest that philosophical debate about the precise reasons for that judgement is lively
and ongoing.
Acknowledgements
Thanks to Dominic Roser, Kasper Lippert-Rasmussen and two anonymous referees for their
helpful comments on an earlier draft of this article.
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