. 9
( 13)


to be considered in
developing climate and
Emissions scenarios related scenarios for
climate change impact,
Policy responses: adaptation and mitigation

adaptation and mitigation
Concentration projections assessment. The chapters
(WGI/Ch 3,4,5) in the IPCC 2001 Report
that deal with the various

Interactions and feedbacks
(WGI/Ch 3,4,5,7; WGII/Ch3)
components are also
Radiative forcing projections

(WGI/Ch 6) identi¬ed.

Climate projections
(WGI/Ch 8,9,10)

Sea level projections Climate scenarios
(WGI/Ch 11) (WGI/Ch 13)

Global change scenarios
(WGII/Ch 3)


(UNEP). The IPCC™s ¬rst meeting in November 1988 was timely; it was
held just as strong political interest in global climate change was be-
ginning to develop. The Panel realised the urgency of the problem and,
under the overall chairmanship of Professor Bert Bolin from Sweden,
established three working groups, one to deal with the science of climate
change, one with impacts and a third one to deal with policy responses.
The IPCC has produced three main comprehensive Reports,3 in 1990,
1995 and 2001, together with a number of special reports covering par-
ticular issues. Previous chapters have already referred widely to these
I would like to say more about the Science Assessment Working
Group (of which I was chairman from 1988 until 1992 and co-chairman
from 1992 until 2002).4 Its task has been to present in the clearest poss-
ible terms our knowledge of the science of climate change together with
our best estimate of the climate change over the twenty-¬rst century that
is likely to occur as a result of human activities. In preparing its reports
the Working Group realised from the start that if they were to be really
authoritative and taken seriously, it would be necessary to involve as
many as possible of the world scienti¬c community in their production.
220 Weighing the uncertainty

A small international organising team was set up at the Hadley Centre
of the United Kingdom Meteorological Of¬ce at Bracknell and through
meetings, workshops and a great deal of correspondence most of those
scientists in the world (both in universities and government-supported
laboratories) who are deeply engaged in research into the science of cli-
mate change were involved in the preparation and writing of the reports.
For the ¬rst report, 170 scientists from 25 countries contributed and a
further 200 scientists were involved in its peer review. For the third as-
sessment report in 2001, these numbers had grown to 123 lead authors
and 516 contributing authors involved with the various chapters, together
with 21 review editors and 420 expert reviewers involved in the review
In addition to the comprehensive, thorough and intensively reviewed
background chapters that form the basic material for each assessment,
each report includes a Summary for Policymakers (SPM), the wording of
which is approved in detail at a plenary meeting of the Working Group,
the object being to reach agreement on the science and on the best way of
presenting the science to policymakers with accuracy and clarity. The ple-
nary meeting which agreed unanimously the 2001 SPM, held in Shanghai
in January 2001,was attended by representatives of 99 countries and 45
scientists representing the lead authors of the scienti¬c chapters together
with a number of representatives from non-governmental organisations.
There has been very lively discussion at these plenary meetings, most
of which has been concerned with achieving the most informative and
accurate wording rather than fundamental dispute over scienti¬c content.
During the preparation of the reports, a considerable part of the
debate amongst the scientists has centred on just how much can be said
about the likely climate change in the twenty-¬rst century. Particularly
to begin with, some felt that the uncertainties were such that scientists
should refrain from making any estimates or predictions for the future.
However, it soon became clear that the responsibility of scientists to
convey the best possible information could not be discharged without
making estimates of the most likely magnitude of the change coupled
with clear statements of our assumptions and the level of uncertainty in
the estimates. Weather forecasters have a similar, although much more
short-term responsibility. Even though they may feel uncertain about
tomorrow™s weather, they cannot refuse to make a forecast. If they do
refuse, they withhold from the public most of the useful information they
possess. Despite the uncertainty in a weather forecast, it provides useful
guidance to a wide range of people. In a similar way the climate models,
although subject to uncertainty, provide useful guidance for policy.
I have given these details of the work of the Science Assessment
Group in order to demonstrate the degree of commitment of the scienti¬c
The IPCC assessments 221

community to the understanding of global climate change and to the
communication of the best scienti¬c information to the world™s politi-
cians and policymakers. After all, the problem of global environmental
change is one of the largest problems facing the world scienti¬c com-
munity. No previous scienti¬c assessments on this or any other subject
have involved so many scientists so widely distributed both as regards
their countries and their scienti¬c disciplines. The IPCC Reports can
therefore be considered as authoritative statements of the contemporary
views of the international scienti¬c community.
A further important strength of the IPCC is that, because it is an inter-
governmental body, governments are involved in its work. In particular,
government representatives assist in making sure that the presentation
of the science is both clear and relevant from the point of view of the
policymaker. Having been part of the process, the resulting assessments
are in a real sense owned by governments as well as by scientists “ an
important factor when it comes to policy negotiations.
In the presentation of the IPCC assessments to politicians and pol-
icymakers, the degree of scienti¬c consensus achieved has been of great
importance in persuading them to take seriously the problem of global
warming and its impact. In the run-up to the United Nations Conference
on Environment and Development (UNCED) at Rio de Janeiro in June
1992, the fact that they accepted the reality of the problem led to the
formulation of the Climate Convention. It has often been commented
that without the clear message that came from the world™s scientists,
orchestrated by the IPCC, the world™s leaders would never have agreed
to sign the Climate Convention.
Since the publication of the reports, the debate concerning the scien-
ti¬c ¬ndings has continued in the world™s press. Many have commented
favourably on their clarity and accuracy. A few scientists have criticised
because they feel the reports have insuf¬ciently emphasised the uncer-
tainties; others have expressed their disappointment that they have not
spelt out the potential dangers to the world more forcefully. The scienti¬c
debate continues as indeed it must; argument and debate are intrinsic to
the scienti¬c process.
I have illustrated the work of the IPCC by describing in some detail
the activity of the Science Assessment Working Group. The IPCC has
two other Working Groups that have followed similar procedures and
have dealt with the Impacts of Climate Change, with Adaptation and
Mitigation strategies and with the Economics and Social Dimensions of
Climate Change. Contributions to their work have not only come from
natural scientists; increasingly social scientists, especially economists,
have become involved. In these social science areas much fresh ground
has been broken as consideration has been given to questions of what,
222 Weighing the uncertainty

in the global context, might form the basis of appropriate political and
economic response to climate change. The rest of this chapter and the
following chapters will draw heavily on their work.

Narrowing the uncertainty
A key question constantly asked by policymakers is, ˜How long will it be
before scientists are more certain about the projections of likely climate
change, in particular concerning the regional and local detail?™ They were
asking that question over a decade ago and then I generally replied that in
ten to ¬fteen years we would know a lot more. As we saw in the ¬rst sec-
tion of this chapter, over the past decade a lot of progress in knowledge has
been made. There is more con¬dence that anthropogenic climate change
has been detected and more con¬dence too in climate change projections
than was the case a decade ago. However, some of the key uncertainties
remain and their reduction is urgently needed. Not surprisingly,
policymakers are still asking for more certainty. What can be done to
provide it?
For the science of change, the main tools of progress are observations
and models. Both need further development and expansion. Observations
are required to detect climate change in all its aspects as it occurs and
also to validate models. That means that regular, accurate and consistent
monitoring of the most important climate parameters is required with
good coverage in both space and time. Monitoring may not sound very
exciting work, often even less exciting is the rigorous quality control
that goes with it, but it is absolutely essential if climate changes are
to be observed and understood. Because of this, a major international
programme, the Global Climate Observing System (GCOS) has been set
up to orchestrate and oversee the provision of observations on a global
basis. Models are needed to integrate all the scienti¬c processes that are
involved in climate change (most of which are non-linear, which means
they cannot be added together in any simple manner) so that they can
assist in the analysis of observations and provide a method of projecting
climate change into the future.
Take, for instance, the example of cloud radiation feedback that re-
mains the source of greatest single uncertainty associated with climate
sensitivity.5 It was mentioned in Chapter 5 that progress with understand-
ing this feedback will be made by formulating better descriptions of cloud
processes for incorporation into models and also by comparing model
output, especially of radiation quantities, with observations especially
those made by satellites. To be really useful such measurements need
to be made with extremely high accuracy “ to within the order of 0.1%
Narrowing the uncertainty 223

in the average radiation quantities “ that is proving highly demanding.
Associated with the better measurements of clouds is the need for all
aspects of the hydrological (water) cycle to be better observed.
There is also inadequate monitoring at present of the major oceans of
the world, which cover a large fraction of the Earth™s surface. However,
this is beginning to be remedied with the introduction of new methods
of observing the ocean surface from space vehicles (see box below)
and new means of observing the interior of the ocean. But not only are
better physical measurements required: to be able to predict the detailed
increases of greenhouse gases in the atmosphere, the problems of the
carbon cycle must be unravelled; for this, much more comprehensive
measurements of the biosphere in the ocean as well as that on land are
Stimulated by internationally organised observing programmes such
as the GCOS, space agencies around the world have been very active
in the development of new instruments and the deployment of advanced
space platforms that are beginning to provide many new observations
relevant to the problems of climate change (see box below).

Space observations of the climate system
For forecasting the weather round the world “ for airlines, for shipping,
for many other applications and for the public “ meteorologists rely
extensively on observations from satellites. Under international agree-
ments, ¬ve geostationary satellites are spaced around the equator for
weather observation; moving pictures from them have become familiar
to us on our television screens. Information from polar orbiting satel-
lites is also available to the weather services of the world to provide input
into computer models of the weather and to assist in forecasting (see for
instance Figure 5.4).
These weather observations provide a basic input to climate models.
But for climate prediction and research, comprehensive observations
from other components of the climate system, the oceans, ice and land
surface are required. ENVISAT, a satellite launched by the European
Space Agency in 2002, is an example of the most recent generation of
large satellites in which the latest techniques are directed to observing the
Earth. The instruments are directed at the measurement of atmospheric
temperature and composition (MIPAS, SCIAMACHY and GOMOS),
sea surface temperature and topography, the latter for ocean current
information (AATSR and RA-2), information about ocean biology and
land surface vegetation (MERIS) and sea-ice coverage and ice-sheet
topography (ASAR and RA-2).
224 Weighing the uncertainty



RA-2 Antenna


Figure 9.2 ENVISAT showing the instruments included in its payload: the
Advanced Along-Track Scanning Radiometer (AATSR), the Michelson
Interferometer for Passive Atmospheric Sounding (MIPAS), the MEdium
Resolution Imaging Spectrometer (MERIS), the SCanning Image Absorption
spectroMeter for Atmospheric CartograpHY (SCIAMACHY), the MicroWave
Radiometer (MWR), the Global Ozone Monitoring by Observation of Stars
(GOMOS), the Radar Altimeter “ second generation (RA-2), the Advanced
Synthetic Aperture Radar (ASAR), and other instruments for communication and
exact tracking. DORIS stands for Doppler Orbitography and Radiopositioning
Integrated by Satellite. In its 800-km Sun-synchronous orbit with the solar array
deployed, it measures 26 m — 10 m — 5 m and weighs 8.1 tonnes.

Alongside the increased understanding and more accurate predic-
tions of climate change coming from the community of natural scien-
tists, much more effort is now going into studies of human behaviour
and activities, how they will in¬‚uence climate through changes in emis-
sions of greenhouse gases and how they in turn might be affected by
different degrees of climate change. Much better quanti¬cation of the
impacts of climate change will result from these studies. Economists
and other social scientists are pursuing detailed work on possible re-
sponse strategies and the economic and political measures that will be
necessary to achieve them. It is also becoming increasingly realised that
Sustainable development 225

there is an urgent need to interconnect more strongly research in the
natural sciences with that in the social sciences. The integrated frame-
work presented in Chapter 1 (Figure 1.5) illustrates the scope of interac-
tions and of required integration between all the intellectual disciplines

Sustainable development
So much for uncertainty in the science of global warming. But how does
this uncertainty map on to the world of political decision making? A key
idea is that of sustainable development.
One of the remarkable movements of the last few years is the way in
which problems of the global environment have moved up the political
agenda. In her speech at the opening in 1990 of the Hadley Centre
at the United Kingdom Meteorological Of¬ce, Margaret Thatcher, the
former British Prime Minister, explained our clear responsibility to the
environment. ˜We have a full repairing lease on the Earth. With the work
of the IPCC, we can now say we have the surveyor™s report; and it shows
there are faults and that the repair work needs to start without delay. The
problems do not lie in the future, they are here and now: and it is our
children and grandchildren, who are already growing up, who will be
affected.™ Many other politicians have similarly expressed their feelings
of responsibility for the global environment. Without this deeply felt and
widely held concern, the UNCED conference at Rio, with environment
as the number one item on its agenda, could never have taken place.
But, despite its importance, even when concentrating on the long
term, the environment is only one of many considerations politicians
must take into account. For developed countries, the maintenance
of living standards, full employment (or something close to it) and
economic growth have become dominant issues. Many developing
countries are facing acute problems in the short term: basic survival
and large debt repayment; others, under the pressure of large increases
in population, are looking for rapid industrial development. However,
an important characteristic of environmental problems, compared with
many of the other issues faced by politicians, is that they are long-term
and potentially irreversible “ which is why Tim Wirth, the Under
Secretary of State for Global Affairs in the United States Government
during the Clinton Administration, said, ˜The economy is a wholly
owned subsidiary of the environment™.
A balance, therefore, has to be struck between the provision of nec-
essary resources for development and the long-term need to preserve the
environment. That is why the Rio Conference was about Environment
and Development. The formula that links the two is called sustainable
226 Weighing the uncertainty

development (see box below) “ development which does not carry with
it the overuse of irreplaceable resources or irreversible environmental
The idea of sustainable development echoes what was said in Chap-
ter 8, when addressing more generally the relationship of humans to their
environment and especially the need for balance and harmony. The Cli-
mate Convention signed at the Rio Conference also recognised the need
for this balance. In the statement of its objective (see box on page 243
in Chapter 10), it states the need for stabilisation of greenhouse gas con-
centrations in the atmosphere. It goes on to explain that this should be
at a level and on a timescale such that ecosystems are allowed to adapt
to climate change naturally, that food production is not threatened and
that economic development can proceed in a sustainable manner.

Sustainable development: how is it de¬ned?
A number of de¬nitions of sustainable development have been produced.
The following two well capture the idea.
According to the Bruntland Commission Report Our Common Fu-
ture presented in 1987, sustainable development is ˜meeting the needs
of the present without compromising the ability of future generations to
meet their own needs™.
A more detailed de¬nition is contained in the White Paper This
Common Inheritance, published by the United Kingdom Department of
the Environment in 1990: ˜sustainable development means living on the
Earth™s income rather than eroding its capital™ and ˜keeping the consump-
tion of renewable natural resources within the limits of their replenish-
ment™. It recognises the intrinsic value of the natural world explaining
that sustainable development ˜means handing down to successive gener-
ations not only man-made wealth (such as buildings, roads and railways)
but also natural wealth, such as clean and adequate water supplies, good
arable land, a wealth of wildlife and ample forests™.
The United Kingdom Government™s ¬rst strategy report on sustain-
able development, issued in January 1994,6 de¬ned four principles that
should govern necessary collective action:
r Decisions should be based on the best possible scienti¬c informa-
tion and analysis of risks.
r Where there is uncertainty and potentially serious risks exist, pre-
cautionary action may be necessary.
r Ecological impacts must be considered, particularly where re-
sources are non-renewable or effects may be irreversible.
r Cost implications should be brought home directly to the people
responsible “ the ˜polluter pays™ principle.
Why not wait and see? 227

It is also increasingly realised that the idea of sustainability not only
applies to the environment but also to human communities. Sustainable
development is often therefore assumed to include wider social factors
as well as environmental and economic ones. The provision of social
justice and equity are important components of a drive to sustainable
communities. Considerations of equity include not just equity between
nations but also equity between generations: we should not leave the
world in a poorer state for the next generation.

Why not wait and see?
In taking action to satisfy the requirements of sustainable development
a balance must be struck between many factors. The following sections
address some of the arguments, issues and principles that are involved
in this debate.
Firstly, in the light of scienti¬c uncertainty, it is often argued that the
case is not strong enough for any action to be taken now. What we should
do is to obtain as quickly as possible, through appropriate research pro-
grammes, much more precise information about future climate change
and its impact. We would then, so the argument goes, be in a much better
position to decide on relevant action.
It is true that more accurate information is urgently needed so that
decisions can be better informed. But in any sensible future planning,
all information about likely future needs has to be taken properly into
account. Decisions now should be informed by the best information
available now, even if it is imperfect.
In the ¬rst place, quite a lot is already known “ enough to scope the
problem as a whole. There is general consensus amongst scientists about
the most likely overall magnitude of climate change and there are good
indications about its probable impact. Although we are not yet very con-
¬dent regarding detailed predictions, enough is known to realise that the
rate of climate change due to increasing greenhouse gases will almost
certainly bring substantial deleterious effects and pose a large problem to
the world. It will hit some countries much more than others. Those worst
hit are likely to be those in the developing world that are least able to
cope with it. Some countries may actually experience a more bene¬cial
climate. But in a world where there is increasing interdependence
between nations, no nation will be immune from the effects.
Secondly, the timescales of both atmospheric and human responses
are long. Carbon dioxide emitted into the atmosphere today will con-
tribute to the increased concentration of this gas and the associated cli-
mate change for over a hundred years. The more that is emitted now, the
more dif¬cult it will be to reduce atmospheric carbon dioxide concen-
tration to the levels that will eventually be required. With regard to the
228 Weighing the uncertainty

human response, the major changes that are likely to be needed, for in-
stance in large-scale infrastructure, will take many decades. Large power
stations that will produce electricity in thirty or forty years™ time are be-
ing planned and built today. The demands that are likely to be placed on
all of us because of concerns about global warming need to be brought
into the planning process now.
Thirdly, many of the required actions not only lead to substantial
reductions in greenhouse gas emissions but they are good to do for other
reasons which bring other direct bene¬ts “ such proposals for action are
often described as ˜no regrets™ proposals. Many actions addressing in-
creased ef¬ciency lead also to net savings in cost (sometimes called ˜win-
win™ measures). Other actions lead to improvements in performance or
additional comfort.
Fourthly, there are more general bene¬cial reasons for some of the
proposed actions. In Chapter 8 it was pointed out that humans are far too
pro¬‚igate in their use of the world™s resources. Fossil fuels are burnt and
minerals are used, forests are cut down and soil is eroded without any
serious thought of the needs of future generations. The imperative of the
global warming problem will help us to use the world™s resources in a
more sustainable way. Further, the technical innovation that will be re-
quired in the energy industry “ in energy ef¬ciency and conservation and
in renewable energy development “ will provide a challenge and oppor-
tunity to the world™s industry to develop important new technologies “
more of that in Chapter 11.

The Precautionary Principle
Some of these arguments for action are applications of what is often
called the Precautionary Principle, one of the basic principles that was
included in the Rio Declaration at the Earth Summit in June 1992 (see box
below). A similar statement is contained in article 3 of the Framework
Convention on Climate Change (see box on page 243 in Chapter 10).
We often apply the Precautionary Principle in our day-to-day living.
We take out insurance policies to cover the possibility of accidents or
losses; we carry out precautionary maintenance on housing or on ve-
hicles, and we readily accept that in medicine prevention is better than
cure. In all these actions we weigh up the cost of insurance or other
precautions against the possible damage and conclude that the invest-
ment is worthwhile. The arguments are very similar as the Precautionary
Principle is applied to the problem of global warming.
In taking out an insurance policy we often have in mind the pos-
sibility of the unexpected. In fact, when selling their policies, insur-
ance companies often trade on our fear of the unlikely or the unknown,
The Precautionary Principle 229

especially of the more devastating possibilities. Although covering our-
selves for the most unlikely happenings is not our main reason for taking
out the insurance, our peace of mind is considerably increased if the
policy includes these improbable events. In a similar way, in arguing for
action concerning global warming, some have strongly emphasised the
need to guard against the possibility of surprises (see examples in Table
7.4). They point out that, because of positive feedbacks that are not yet
well understood,7 the increase of some greenhouse gases could be much
larger than is currently predicted. They also point to the evidence that
rapid changes of climate have occurred in the past (Figures 4.6 and 4.7)
possibly because of dramatic changes in ocean circulation; they could
presumably occur again.
The risk posed by such possibilities is impossible to assess. It is,
however, salutary to call attention to the discovery of the ozone ˜hole™
over Antarctica in 1985. Scienti¬c experts in the chemistry of the ozone
layer were completely taken by surprise by that discovery. In the years
since its discovery, the ˜hole™ has substantially increased in depth. Re-
sulting from this knowledge, international action to ban ozone-depleting
chemicals has progressed much more rapidly. Ozone levels are begin-
ning to recover “ full recovery will take about a century. The lesson for
us here is that the climate system may be more vulnerable to disturbance
than we have often thought it to be. When it comes to future climate
change, it would not be prudent to rule out the possibility of surprises.
However, in weighing the action that needs to be taken with regard
to future climate change, although the possibility of surprises should be
kept in mind, that possibility must not be allowed to feature as the main
argument for action. Much stronger in the argument for precautionary
action is the realisation that signi¬cant anthropogenic climate change is
not an unlikely possibility but a near certainty; it is no change of climate
that is unlikely. The uncertainties that mainly have to be weighed lie in
the magnitude of the change and the details of its regional distribution.
An argument that is sometimes advanced for doing nothing now is
that by the time action is really necessary, more technical options will be
available. By acting now, we might foreclose their use. Any action taken
now must, of course, take into account the possibility of helpful technical
developments. But the argument also works the other way. The thinking
and the activity generated by considering appropriate actions now and
by planning for more action later will itself be likely to stimulate the sort
of technical innovation that will be required.
While speaking of technical options, I should brie¬‚y mention poss-
ible options to counteract global warming by the arti¬cial modi¬cation
of the environment (sometimes referred to as geoengineering).8 A num-
ber of proposals for ˜technical ¬xes™ of this kind have been put forward;
230 Weighing the uncertainty

for instance, the installation of mirrors in space to cool the Earth by
re¬‚ecting sunlight away from it; the addition of dust to the upper at-
mosphere to provide a similar cooling effect and the alteration of cloud
amount and type by adding cloud condensation nuclei to the atmosphere.
None of these has been demonstrated to be either feasible or effective.
Further, they suffer from the very serious problem that none of them
would exactly counterbalance the effect of increasing greenhouse gases.
As has been shown, the climate system is far from simple. The results
of any attempt at large-scale climate modi¬cation could not be perfectly
predicted and might not be what is desired. With the present state of
knowledge, arti¬cial climate modi¬cation along any of these lines is not
an option that needs to be considered.
The conclusion from this section “ and the last one “ is that to ˜wait
and see™ would be an inadequate and irresponsible response to what we
know. The Framework Convention on Climate Change (FCCC) signed
in Rio (see box on page 243 in Chapter 10) recognised that some action
needs to be taken now. Just what that action should be and how it ¬ts in
to a sensible scheme of sequential decision making will be the subject
of the next chapter.

Principles for international action
From the three previous sections, four distinct principles can be iden-
ti¬ed to form the basis of international action. They are all contained
in the Rio Declaration on Environment and Development (see box be-
low) agreed by over 160 countries at the United Nations Conference
on Environment and Development (the ˜Earth Summit™) held in Rio
de Janeiro in 1992. They can also be identi¬ed in one form or an-
other in the FCCC (see box on page 243 in Chapter 10). The Prin-
ciples (with references to the Principles of the Rio Declaration and the
Articles of the FCCC) are:
r The Precautionary Principle (Principle 15)
r The Principle of Sustainable Development (Principles 1 and 7)
r The Polluter-Pays Principle (Principle 16)
r The Principle of Equity “ International and Intergenerational (Princi-
ples 3 and 5)

In the next chapter we shall consider how these principles can be applied.

Some global economics
So far in this chapter, our attempt to balance uncertainty against the need
for action has been considered in terms of issues. Is it possible to carry
Some global economics 231

The Rio Declaration 1992
The Rio Declaration on Environment and Development was agreed by
over 160 countries at the United Nations Conference on Environment and
Development (the ˜Earth Summit™) held in Rio de Janeiro in 1992. Some
examples of the twenty-seven principles enumerated in the Declaration
are as follows:

Principle 1 Human beings are at the centre of concerns for sustain-
able development. They are entitled to a healthy and productive life in
harmony with nature.

Principle 3 The right to development must be ful¬lled so as to equitably
meet developmental and environmental needs of present and future gen-
Principle 5 All States and all people shall cooperate in the essential task
of eradicating poverty as an indispensable requirement for sustainable
development, in order to decrease the disparities in standards of living
and better meet the needs of the majority of the people of the world.
Principle 7 States shall cooperate in a spirit of global partnership to
conserve, protect and restore the health and integrity of the Earth™s
ecosystem. In view of the different contributions to global environmen-
tal degradation, States have common but differentiated responsibilities.
The developed countries acknowledge the responsibility they bear in the
international pursuit of sustainable development in view of the pressures
their societies place on the global environment and of the technologies
and ¬nancial resources they command.

Principle 15 In order to protect the environment, the precautionary ap-
proach shall be widely applied by States according to their capabilities.
Where there are threats of serious or irreversible damage, lack of full
scienti¬c certainty shall not be used as a reason for postponing cost-
effective measures to prevent environmental degradation.
Principle 16 National authorities should endeavour to promote the inter-
nalisation of environmental costs and the use of economic instruments,
taking into account the approach that the polluter should, in principle,
bear the cost of pollution, with due regard to the public interest and
without distorting international trade and investment.

out the weighing in terms of cost? In a world that tends to be dominated
by economic arguments, quanti¬cation of the costs of action against the
likely costs of the consequences of inaction must at least be attempted.
It is also helpful to put these costs in context by comparing them with
other items of global expenditure.
232 Weighing the uncertainty

The costs of anthropogenic climate change fall into three parts.
Firstly, there is the cost of the damage due to that change; for instance,
the cost of ¬‚ooding due to sea level rise or the cost of the increase in
the number or intensity of disasters such as ¬‚oods, droughts or wind-
storms, and so on. Secondly, there is the cost of adaptation that reduces
the damage or the impact of the climate change. Thirdly, there is the
cost of mitigating action to reduce the amount of climate change. The
roles of adaptation and mitigation are illustrated in Figure 1.5. Because
there is already a commitment to a signi¬cant degree of climate change,
a need for signi¬cant adaptation is apparent. That need will continue to
increase through the twenty-¬rst century, an increase that will eventually
be molli¬ed as the effects of mitigation begin to bite. Mitigation is be-
ginning now but the degree of mitigation that is eventually undertaken
will depend on an assessment of the effectiveness and cost of adaptation.
The costs, disadvantages and bene¬ts of both adaptation and mitigation
need therefore to be assessed and weighed against each other.
At the end of Chapter 7, estimates of the cost of damage from global
warming were presented. Many of these estimates of damage cost also
included some of the costs of adaptation; in general adaptation costs have
not been separately identi¬ed. Many of these cost estimates assumed
a situation for which, resulting from human activities, the increase in
greenhouse gases in the atmosphere was equivalent to a doubling of the
carbon dioxide concentration “ under business-as-usual this is likely to
occur around the middle of the twenty-¬rst century. The estimates were
typically around one to two per cent of gross domestic product (GDP)
for developed countries. In developing countries, because of their greater
vulnerability to climate change and because a greater proportion of their
expenditure is dependent on activities such as agriculture and water,
estimates of the cost of damage are greater, typically about ¬ve per cent
of GDP or more. At the present stage of knowledge, these estimates
are bound to be crude and subject to large uncertainties; nevertheless,
they give a feel for the likely range of cost. It was also pointed out in
Chapter 7 that the cost estimates only included those items that could
be costed in money terms. Those items of damage or disturbance for
which money is not an appropriate measure (e.g. the generation of large
numbers of environmental refugees) also need to be to exposed and taken
into account in any overall appraisal.
The longer-term damage, should greenhouse gases more than double
in concentration, is likely to rise somewhat more steeply in relation to the
concentration of carbon dioxide (Figure 9.3). For quadrupled equivalent
carbon dioxide concentration, for instance, estimates of damage cost
of the order of two to four times that for doubled carbon dioxide have
been made “ suggesting that the damage might follow something like a
quadratic law relative to the expected temperature rise.9 In addition the
Some global economics 233

Figure 9.3 The
application of classical cost
bene¬t analysis to the
mitigation of climate
change, showing the
shape of the curve of
damage costs and
mitigation costs as a
function of atmospheric
carbon dioxide emissions.
On the assumption that
economic costs are the
only consideration, the
arrow shows the ˜optimal™
reduction level.
much larger degree of climate change would considerably enhance the
possibilities of singular events (see Table 7.4), irreversible change and
of possible surprises.
Since the main contribution to global warming arises from carbon
dioxide emissions, attempts have also been made to express these costs
in terms of the cost per tonne of carbon as carbon dioxide emitted from
human activities. A simple, but crude calculation can be carried out as
follows. Consider the situation when carbon dioxide concentration in
the atmosphere has doubled from its pre-industrial value, which will
occur when an additional amount of carbon as carbon dioxide of about
800 Gt from anthropogenic sources has been emitted into the atmosphere
(see Figure 3.1 and recall that about half the carbon dioxide emitted
accumulates in the atmosphere). This carbon dioxide will remain in the
atmosphere on average for about one hundred years. Assuming a ¬gure
of two per cent of global world product (GWP) “ or $US 600 billion per
annum “ as the cost of the damage due to global warming in that situation,
and assuming also that the damage remains over the one hundred years
of the life-time of carbon dioxide in the atmosphere, the cost per tonne
of carbon turns out to be about $US 70.
Calculations of the cost per tonne of carbon can be made with much
more sophistication by considering that it is the incremental damage cost
(that is, the cost of the damage due to one extra tonne of carbon emitted
now) that is really required and also by allowing through a discount rate
for the fact that it is damage some time in the future that is being costed
now. Estimates made by different economists then range over $US 5“125
per tonne of carbon10 “ the very large range being due to the different as-
sumptions that have been made. The estimates are particularly sensitive
to the discount rate that is assumed; values at the top end of the range
above about $US 50 have assumed a discount rate of less than two per
cent; those at the bottom end have assumed a discount rate around ¬ve
per cent.11 The dominant effect of the discount rate will be clear when it
is realised that over ¬fty years a two per cent discount rate devalues costs
234 Weighing the uncertainty

by a factor of about three while a ¬ve per cent rate discounts by a factor
of thirteen. Over one hundred years the difference is even larger “ a fac-
tor of seven for a two per cent rate and a factor of 170 for a ¬ve per cent
rate. Amongst economists there has been much debate but no agreement
about how to apply discount accounting to long-term problems of this
sort or about what rate is most appropriate. However, as Partha Dasgupta
points out,12 ˜the disagreement is not about economics nor about social
cost-bene¬t analysis nor even about the numeracy of fellow scientists™.
He explains, for instance, that the effects of carbon emissions could make
substantial negative perturbations on future economies thus threatening
the basis on which discount rates for future investment are set. Further,
there are the likely damages that cannot easily be valued in money terms
such as the large-scale loss of land “ or even of whole countries “ due
to sea level rise or the large-scale loss of habitats or species. For these,
even if valuation is attempted, discounting seems inappropriate. There
seem cogent arguments that, if discount rates are applied to cost esti-
mating for climate change, a smaller discount rate rather than a larger
one should be employed. And in any case, for any cost estimate that
is made the discount rate used should be adequately exposed. For our
broad economic arguments in later chapters we shall therefore quote an
estimate of damage cost in the range $US 50 to $US 100 per tonne of
carbon emitted as carbon dioxide.
To slow the onset of climate change and to limit the longer-term
damage, mitigating action can be taken by reducing greenhouse gas
emissions, in particular the emissions of carbon dioxide. The cost of
mitigation is very dependent on the amount of reduction required in
greenhouse gas emissions; large reductions will cost proportionately
more than small ones. It will also depend on the timescale of reduction.
To reduce emissions drastically in the very near term would inevitably
mean large reductions in energy availability with signi¬cant disruption
to industry and large cost. However, more gradual reductions can be
made with relatively small cost through actions of two kinds. Firstly,
substantial ef¬ciency gains in the use of energy can easily be achieved,
many of which would lead to cost savings; these can be put into train now.
Secondly, in the generation of energy, again proven technology exists
for substantial ef¬ciency improvements and also for the bringing into
use of renewable sources of energy generation that are not dependent on
fossil fuels. These can be planned for now and changes made as energy
infrastructure, which has a typical life of thirty years or so, becomes
ready for replacement. The next two chapters will present more detail
about these possible actions and how they might be achieved.
Our purpose here is to look brie¬‚y at the likely overall cost of miti-
gation, much of which will arise in the energy or the transport sectors as
Some global economics 235

Percentage reduction relative to baseline
4.0 A1B

2.5 A1FI

1.0 B1

450 550 650 750
Eventual CO2 stabilisation level (ppm)

Figure 9.4 Global average GDP reduction in 2050 (relative to the baseline
scenarios) for alternative stabilisation targets (see Chapter 10) and six SRES
scenarios as baselines.

cheap fossil fuels are replaced by other energy sources that, at least in
the short term, are likely to be more expensive. Some detail is provided
in the next chapter of the pro¬le of reductions in emissions that are
required to stabilise carbon dioxide concentrations in the atmosphere
at different levels over the next one or two hundred years. Figure 9.4
presents estimates from six economic models of the cost to the world™s
economy in the year 2050 of these reductions. As might be expected,
the cost is substantially dependent on the target level of carbon dioxide
concentration stabilisation. It is also dependent on the baseline scenario
that is assumed. With typical levels of economic growth being between
two and four per cent per annum, the cost of achieving reductions to
meet any of the stabilisation levels in the ¬gure, even that at 450 ppm,
is less than one year™s economic growth over ¬fty years.
However, it should be noted that, even if the carbon dioxide con-
centration is stabilised at 450 or 500 ppm, remembering that the effect
of increases in the other greenhouse gases also has to be included (see
Chapter 10, page 259), the world will have been committed to a sig-
ni¬cant degree of climate change (close to equivalent to doubling of
atmospheric carbon dioxide concentration), bringing with it substantial
costs and demands for adaptation. What is being mitigated is further and
even more damaging climate change.
Although the economic studies I have mentioned have attempted
to take into account many of the relevant factors, they are bound to be
surrounded by substantial uncertainty. For instance, they have mostly
236 Weighing the uncertainty

not rigorously accounted for the economic effects of introducing new
low-emission technologies, new revenue-raising instruments or adequate
inter-regional ¬nancial and technology transfers, all elements which con-
tribute to lower costs.13 Further, one of the most dif¬cult factors to take
into account is that of likely future innovation. It is not easy to peer into
the crystal ball of technical development; almost any attempt to do so is
likely to underestimate its potential. For these reasons the estimates of
mitigation cost are almost certainly on the high side.
The models that have been used to make the estimates of cost have
all addressed limited parts of the whole problem. A complete assessment
needs to address more completely the interactions between the factors
that are driving climate change and its impacts both on humans and
ecosystems, the human activities that are in¬‚uencing those factors and
the response to climate change both of humans and ecosystems “ in fact
all the elements illustrated in Figure 1.5. This is often called Integrated
Assessment (see box below) and is supported by Integrated Assessment
Models (IAMs) that are currently being built to address all the relevant
elements in a more complete manner.
In considering the costs of the impacts of both global warming and
adaptation or mitigation, ¬gures of a small percentage of GDP have been
mentioned. It is interesting to compare this with other items of expendi-
ture in national or personal budgets. In a typical developed country, for
example the United Kingdom, about ¬ve per cent of national income is
spent on the supply of primary energy (basic fuel such as coal, oil and
gas, fuel for electricity supply and fuel for transport), about nine per cent
on health and three to four per cent on defence. It is, of course, clear that
global warming is strongly linked to energy production “ it is because of
the way energy is provided that the problem exists “ and this subject will
be expanded in the next two chapters. But the impacts of global warming
also have implications for health “ such as the possible spread of disease “
and for national security “ for example, the possibility of wars fought
over water, or the impact of large numbers of environmental refugees.
Any thorough consideration of the economics of global warming needs
therefore to assess the strength of these implications and to take them
into account in the overall economic balance.
So far, on the global warming balance sheet we have estimates of
costs and of bene¬ts or drawbacks. What we do not have as yet is a capital
account. Valuing human-made capital is commonplace, but in the overall
accounting we are attempting, ˜natural™ capital must clearly be valued
too. By ˜natural™ capital is meant, for instance, natural resources that
may be renewable (such as a forest) or non-renewable (such as coal, oil
or minerals).16 Their value is clearly more than the cost of exploitation
or extraction.
Some global economics 237

Integrated Assessment and Evaluation14

Integrated Assessment Models or IAMs are im-
In the assessment and evaluation of the impacts of
portant tools for Integrated Assessment and Evalu-
different aspects of global climate change with its
ation. They represent within one integrated numer-
large complexity, it is essential that all components
ical model the physical, chemical and biological
are properly addressed. The major components are
processes that control the concentration of green-
illustrated in Figure 1.5. They involve a very wide
house gases in the atmosphere, the physical pro-
range of disciplines from natural sciences, technol-
cesses that determine the effect of changing green-
ogy, economics and the social sciences (including
house gas concentrations on climate and sea level,
ethics). Take the example of sea level rise “ probably
the biology and ecology of ecosystems (natural and
the easiest impact to envisage and to quantify. From
managed), the physical and human impacts of cli-
the natural sciences, estimates can be made of the
mate change and the socio-economics of adaptation
amount and rate of rise and its characteristics. From
to and mitigation of climate change. Such models
various technologies, options for adaptation can be
are highly sophisticated and complex although
proposed. From economics and the social sciences,
their components are bound to be very simpli¬ed.
risks can be assessed and evaluated. The economic
They provide an important means for studying the
costs of sea level rise might be expressed, for in-
connections and interactions between the various
stance, most simply as the capital cost of protection
elements of the climate change problem. Because
(where protection is possible) plus the economic
of their complexity and because of the non-linear
value of the land or structures that may be lost
nature of many of the interactions, a great deal of
plus the cost of rehabilitating those persons that
care and skill is needed in interpreting the results
could be displaced. But in practice the situation is
from such models.
more complex. For a costing to be at all realistic,
A number of the components of impact, even
especially when it is to apply to periods of decades
for the relatively simple situation of sea level rise,
into the future, it must account not only for direct
cannot be readily costed in money terms. For in-
damage and the cost of protection but also for a
stance, the loss of ecosystems or wildlife as it
range of options and possibilities for adaptation
impacts tourism can be expressed in money terms,
other than direct protection. The likelihood of in-
but there is no agreed way of setting a money mea-
creased storm surges with the consequent damages
sure for the longer-term loss or the intrinsic value
and the possibility of substantial loss of life need
of unique systems. Or a further example is that,
also to be addressed. Further, there are other indi-
although the cost of rehabilitation for displaced
rect consequences; for instance, the loss of fresh
people can be estimated, other social, security or
water because of salination, the loss of wetlands
political consequences of displacement (e.g. in ex-
and associated ecosystems, wildlife or ¬sheries
treme cases the loss of whole islands or even whole
and the lives and jobs of people that would be af-
states) cannot be costed in terms of money. Any
fected in a variety of ways. In developed country
appraisal therefore of impacts of anthropogenic cli-
situations rough estimates of the costs of some of
mate change will have to draw together components
these components can be made in money terms.
that are expressed in different ways or use different
For developing countries, however, the possible
measures. Policy and decision makers need to ¬nd
options can less easily be identi¬ed or weighed
ways of considering alongside each other all the
and even rough estimates of costs cannot be
components that need to be aggregated in order to
make appropriate judgements.15
238 Weighing the uncertainty

Other items, some of which were mentioned at the end of Chapter 7,
such as natural amenity and the value of species, can also be considered
as ˜natural™ capital. I have argued (Chapter 8) that there is intrinsic value
in the natural world “ indeed, the value and importance of such ˜natural™
capital is increasingly recognised. The dif¬culty is that it is neither pos-
sible nor appropriate to express much of this value in money. Despite
this dif¬culty, it is now widely recognised that national and global indi-
cators of sustainable development should be prepared that include items
of ˜natural™ capital and ways of including such items in national balance
sheets are being actively pursued.
In summary, the items in the overall global warming balance sheet
that have been identi¬ed are:
r Estimates of cost (for those items which can be quanti¬ed in terms of
money) of the likely impacts of anthropogenic climate change. Most
of the estimates to date have costed the impacts supposing the equiva-
lent atmospheric carbon dioxide concentration were to double (which
could occur during the second half of the twenty-¬rst century). When
some allowance is also included for the costs of extreme events (see
Chapter 7, page 179) they are typically around one to two per cent
of GDP in developed countries and typically ¬ve per cent or more in
developing countries.
r Estimates of the cost of adaptation to anthropogenic climate change.
Signi¬cant levels of adaptation will be required to the substantial de-
gree of climate change to which the world is already committed. Even
if the maximum possible mitigation takes place, because of the long
time constants of change, the requirement for adaptation will continue
for many centuries into the future, for instance to respond to the sea
level rise that will continue for many centuries. Very few estimates
have, as yet, been made of adaptation costs, although a few such costs
are included in some of the impact studies.
r Estimates of the impacts of anthropogenic climate change that are dif¬-
cult if not impossible to value in money terms; for instance, those with
social consequences, those that affect human amenity and ˜natural™
capital or those that have implications for national security.
r Estimates of the cost of mitigation of anthropogenic climate change.
For reductions in emissions leading to stabilisation of atmospheric
carbon dioxide concentration (even at a level as low as 450 ppm “
doubled pre-industrial carbon dioxide is 560 ppm) these are typically
less than one year™s economic growth by 2050.
There is already international acceptance that action to mitigate
global warming is necessary. Such ˜weighing™ of the economics as has
been possible so far brings two messages “ that action must begin now to
Questions 239

reduce emissions and slow the rate of change; that emissions of green-
house gases up to the present have already produced a commitment to
signi¬cant climate change over the next decades implying substantial re-
quirements for adaptation and that more substantial emissions reductions
will eventually be required for which planning must begin now.
The next chapter will consider some of the actions in more detail in
the light of the principles we have enunciated in this chapter and in the
context of the international Framework Convention on Climate Change.

1 It is sometimes argued that, in scienti¬c enquiry, ˜consensus™ can never be
achieved, because debate and controversy are fundamental to the search
for scienti¬c truth. Discuss what is meant by ˜consensus™ and whether you
agree with this argument. Do you think the IPCC Reports have achieved
2 How much do you think the value of IPCC Reports depends on (1) the peer
review process to which they have been subjected, and (2) the involvement
of governments in the presentation of scienti¬c results?
3 Look out as many de¬nitions of ˜sustainable development™ as you can ¬nd.
Discuss which you think is the best.
4 Make a list of appropriate indicators that might be used to assess the degree
to which a country is achieving sustainable development. Which do you think
might be the most valuable?
5 Work out the value of a ˜cost™ today if it is twenty, ¬fty or one hundred
years into the future and the assumed discount rate is one, two or ¬ve per
cent. Look up and summarise the arguments for discounting future costs as
presented for instance in various chapters of the IPCC 1995 and the IPCC
2001 Reports.17 What do you think is the most appropriate discount rate to
6 Construct, as far as you are able, a set of environmental accounts for your
country including items of ˜natural™ capital. Your accounts will not neces-
sarily be all in terms of money.
7 Because of continuing economic growth, there is an expectation that the
world will be very much richer by the middle of the twenty-¬rst century
and therefore, it is sometimes argued, in a better position than now to tackle
the impacts or the mitigation of climate change. Do you agree with this

Notes for Chapter 9
1 Houghton, J. T., Jenkins, G. J., Ephraums, J. J. (eds.) 1990. Climate Change:
the IPCC Scienti¬c Assessments. Cambridge: Cambridge University Press,
p. 365; Executive Summary, p. xii. Similar but more elaborate statements are
in the 1995 and the 2001 IPCC Reports.
240 Weighing the uncertainty

2 For a detailed description of how the output from climate models can be com-
bined with other information in climate studies see Mearns, L. O., Hulme,
M. et al. 2001. Climate scenario development. In Houghton, J. T., Ding, Y.,
Griggs, D. J., Noguer, M., van der Linden, P. J., Dai, X., Maskell, K., Johnson,
C. A. (eds.) Climate Change 2001: The Scienti¬c Basis. Contribution of Work-
ing Group I to the Third Assessment Report of the Intergovernmental Panel
on Climate Change. Cambridge: Cambridge University Press, Chapter 13.
3 Houghton, Climate Change: the IPCC Scienti¬c Assessment, 1990.
McG. Tegert, W. J., Sheldon, G. W., Grif¬ths, D. C. (eds.) 1990. Climate
Change: the IPCC Impacts Assessment. Canberra: Australian Government
Publishing Service.
Houghton, J. T., Meira Filho, L. G., Callander, B. A., Harris, N., Kattenberg,
A., Maskell, K. (eds.) 1996. Climate Change 1995: the Science of Climate
Change. Cambridge: Cambridge University Press.
Watson, R. T., Zinyowera, M. C., Moss, R. H. (eds.) 1996. Climate Change
1995: Impacts, Adaptations and Mitigation of Climate Change: Scienti¬c-
Technical Analyses. Contribution of Working Group II to the Second Assess-
ment Report of the Intergovernmental Panel on Climate Change. Cambridge:
Cambridge University Press.
Bruce, J., Hoesung Lee, Haites, E. (eds.) 1996. Climate Change 1995: Eco-
nomic and Social Dimensions of Climate Change. Cambridge: Cambridge
University Press.
Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai,
X., Maskell, K., Johnson, C. A. (eds.) Climate Change 2001: The Scienti¬c
Basis. Contribution of Working Group I to the Third Assessment Report of the
Intergovernmental Panel on Climate Change. Cambridge: Cambridge Uni-
versity Press.
McCarthy, J. J., Canziani, O., Leary, N. A., Dokken, D. J., White, K. S. (eds.)
2001. Climate Change 2001: Impacts, Adaptation and Vulnerability. Con-
tribution of Working Group II to the Third Assessment Report of the Inter-
governmental Panel on Climate Change. Cambridge: Cambridge University
Metz, B., Davidson, O., Swart, R., Pan, J. (eds.) 2001. Climate Change 2001:
Mitigation. Contribution of Working Group III to the Third Assessment Report
of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge
University Press.
4 See also Houghton, J. T. 2002. An overview of the IPCC and its process of
science assessment. In Hester, R. E., Harrison, R. M. (eds.) Global Environ-
mental Change. Issues in Environmental Science and Technology, No. 17.
London: Royal Society of Chemistry.
5 De¬ned on page 120 in Chapter 6.
6 Sustainable Development: the UK Strategy. 1994. London: HMSO, Cm 2426,
p. 7.
7 See Chapter 3.
8 Reviewed in Policy Implications of Greenhouse Warming. 1992. Washington
DC: National Academy Press, pp. 433“64.
Notes 241

9 Pearce, D. W. et al. 1996. In Bruce, Climate Change 1995: Economic and
Social Dimensions, Chapter 6.
10 Summary for policymakers. In Bruce, Climate Change 1995: Economic and
Social Dimensions.
11 Cline argues for a low rate (Cline, W. R. 1992. The Economics of Global
Warming. Washington DC: Institute for International Economics, Chap-
ter 6). Nordhaus (Nordhaus, W. R. 1994. Managing the Global Commons:
the Economics of Climate Change. Massachusetts: MIT Press) has used rates
in the range of ¬ve to ten per cent; see also Tol, R. S. J. 1999. The marginal
costs of greenhouse gas emissions. The Energy Journal, 20, pp. 61“81.
12 Dasgupta, P. 2001. Human Well-Being and the Natural Environment. Oxford:
Oxford University Press, p. 184, see also pp. 183“91; see also Markhndya,
A., Halsnaes, K. et al. Costing methodologies. In Metz, Climate Change
2001: Mitigation, Chapter 7.
13 Further detail in Hourcade, J.-C., Shukla, P. et al. 2001. Global regional and
national costs and ancillary bene¬ts of mitigation. In Metz, Climate Change
2001: Mitigation, Chapter 8.
14 Weyant, J. et al. Integrated assessment of climate change. In Bruce, Climate
Change 1995: Economic and Social Dimensions, Chapter 10.
15 A full discussion of such integrated appraisal can be found in 21st Report of
the UK Royal Commission on Environmental Pollution. London: Stationery
16 For a discussion of this issue see Daly, H. E. 1993. From empty-world eco-
nomics to full-world economics: a historical turning point in economic de-
velopment. In Ramakrishna, K., Woodwell, G. M. (eds.) World Forests for
the Future. Princeton: Yale University Press, pp. 79“91.
17 Bruce, Climate Change 1995: Economic and Social Dimensions; Metz,
Climate Change 2001: Mitigation.
Chapter 10
A strategy for action to slow
and stabilise climate change

Following the awareness of the problems of climate change aroused
by the IPCC scienti¬c assessments, the necessity of international action
has been recognised. In this chapter I address the forms that action could

The climate convention
The United Nations Framework Convention on climate change signed by
over 160 countries at the United Nations Conference on Environment and
Development held in Rio de Janeiro in June 1992 came into force on 21
March 1994. It has set the agenda for action to slow and stabilise climate
change. The signatories to the Convention (some of the detailed wording
is presented in the box below) recognised the reality of global warming,
recognised also the uncertainties associated with current predictions of
climate change, agreed that action to mitigate the effects of climate
change needs to be taken and pointed out that developed countries should
take the lead in this action.
The Convention mentions one particular aim concerned with the
relatively short-term and one far reaching objective. The particular aim
is that developed countries (Annex I countries in Climate Convention
parlance) should take action to return greenhouse gas emissions, in par-
ticular those of carbon dioxide, to their 1990 levels by the year 2000.
The long-term objective of the Convention, expressed in Article 2, is
that the concentrations of greenhouse gases in the atmosphere should be
stabilised ˜at a level which would prevent dangerous anthropogenic inter-
ference with the climate system™, the stabilisation to be achieved within

Some extracts from the United Nations Framework Convention on climate
change, signed by over 160 countries in Rio de Janeiro in June 1992

Firstly, some of the paragraphs in its preamble, dangerous anthropogenic interference with the
where the parties to the Convention: climate system. Such a level should be achieved
within a time frame suf¬cient to allow ecosys-
CONCERNED that human activities have been
tems to adapt naturally to climate change, to en-
substantially increasing the atmospheric concentra-
sure that food production is not threatened and
tion of greenhouse gases, that these increases en-
to enable economic development to proceed in a
hance the natural greenhouse effect, and that this
sustainable manner.
will result on average in an additional warming of
the Earth™s surface and atmosphere and may ad- Article 3 deals with principles and includes agree-
versely affect natural ecosystems and humankind. ment that the Parties:
NOTING that the largest share of historical and cur- take precautionary measures to anticipate, pre-
rent global emissions of greenhouse gases has orig- vent or minimize the causes of climate change
inated in developed countries, that per capita emis- and mitigate its adverse effects. Where there are
sions in developing countries are still relatively low threats of serious or irreversible damage, lack of
and that the share of global emissions originating in full scienti¬c certainty should not be used as a
developing countries will grow to meet their social reason for postponing such measures, taking into
and development needs. account that policies and measures to deal with
RECOGNISING that various actions to address cli- climate change should be cost-effective so as to
mate change can be justi¬ed economically in their ensure global bene¬ts at the lowest possible cost.
own right and can also help in solving other envi-
Article 4 is concerned with Commitments. In this
ronmental problems.
article, each of the signatories to the Convention
RECOGNISING that low-lying and other small is- agreed:
land countries, countries with low-lying coastal,
to adopt national policies and take corresponding
arid and semi-arid areas or areas liable to ¬‚oods,
measures on the mitigation of climate change, by
drought and deserti¬cation, and developing coun-
limiting its anthropogenic emissions of green-
tries with fragile mountainous ecosystems are par-
house gases and protecting and enhancing its
ticularly vulnerable to the adverse effects of climate
greenhouse sinks and reservoirs. These policies
and measures will demonstrate that developed
AFFIRMING that responses to climate change countries are taking the lead in modifying longer-
should be coordinated with social and economic term trends in anthropogenic emissions consis-
development in an integrated manner with a view tent with the objective of the Convention, recog-
to avoiding adverse impacts on the latter, taking into nizing that the return by the end of the present
full account the legitimate priority needs of devel- decade to earlier levels of anthropogenic emis-
oping countries for the achievement of sustained sions of carbon dioxide and other greenhouse
economic growth and the eradication of poverty. gases not controlled by the Montreal Protocol
DETERMINED to protect the climate system for would contribute to such modi¬cation . . .
present and future generations, have AGREED as
Each signatory also agreed:
in order to promote progress to this end . . . to
The Objective of the Convention is contained in
communicate . . . detailed information on its poli-
Article 2 and reads as follows:
cies and measures referred to above, as well as
The ultimate objective of this Convention and any
on its resulting projected anthropogenic emis-
related legal instruments that the Conference of
sions by sources and removals by sinks of green-
the Parties may adopt is to achieve, in accordance
house gases not covered by the Montreal Proto-
with the relevant provisions of the Convention,
col . . . with the aim of returning individually or
stabilization of greenhouse gas concentrations
jointly to their 1990 levels these . . . emissions . . .
in the atmosphere at a level that would prevent
244 A strategy for action to slow and stabilise climate change

a time-frame suf¬cient to allow ecosystems to adapt naturally to climate
change, to ensure that food production is not threatened and to enable
economic development to proceed in a sustainable manner. In setting this
objective, the Convention has recognised that it is only by stabilising the
concentration of greenhouse gases (especially carbon dioxide) in the
atmosphere that the rapid climate change which is expected to occur
with global warming can be halted.
Up to the end of 2003, nine sessions of the Conference of the Par-
ties to the Climate Convention have taken place. Those since November
1997 have largely been concerned with the Kyoto Protocol, the ¬rst
formal binding legislation promulgated under the Convention. The fol-
lowing paragraphs will ¬rst outline the actions taken so far, then de-
scribe the Kyoto Protocol and address the further actions necessary
to satisfy the Convention™s objective to stabilise greenhouse gas con-
centrations. Scienti¬c and technical details of the options available
to achieve the reductions in emissions required will be described in
Chapter 11.

Stabilisation of emissions
The target for short-term action proposed for developed countries by
the Climate Convention was that, by the year 2000, greenhouse gas
emissions should be brought back to no more than their 1990 levels.
In the run-up to the Rio conference, before the Climate Convention
was formulated, many developed countries had already announced their
intention to meet such a target at least for carbon dioxide. They would do
this mainly through energy-saving measures, through switching to fuels
such as natural gas, which for the same energy production generates
forty per cent less carbon dioxide than coal and twenty-¬ve per cent less
than oil. In addition those countries with traditional heavy industries
(e.g. the iron and steel industry) were experiencing large changes which
signi¬cantly reduce fossil fuel use. More detail of these energy-saving
measures are given in the next chapter, which is devoted to a discussion
of future energy needs and production.
By the year 2000, compared with 1990, global emissions from fossil
fuel burning had risen by ten per cent. There was great variation between
the emissions from different countries. In the USA they rose by seventeen
per cent, in the rest of the OECD (Organization of Economic Cooperation
and Development) they rose on average by ¬ve per cent. Emissions in
countries in the former Soviet Union (FSU “ also often called Economies
in Transition) fell by around forty per cent because of the collapse of
their economies, while the total of emissions from developing countries
The Montreal Protocol 245

increased by around thirty-seven per cent (China and India by about
nineteen and sixty-eight per cent respectively).
As we shall learn later in the chapter, stabilisation of carbon dioxide
emissions would not lead in the foreseeable future to stabilisation of
atmospheric concentrations. Stabilisation of emissions could only be a
short-term aim. In the longer term much more substantial reductions of
emissions are necessary.

The Montreal Protocol
The chloro¬‚uorocarbons (CFCs) are greenhouse gases whose emissions
into the atmosphere are already controlled under the Montreal Protocol
on ozone-depleting substances. This control has not arisen because
of their potential as greenhouse gases, but because they deplete
atmospheric ozone (see Chapter 3). Emissions of CFCs have fallen
sharply during the last few years and the growth in their concentrations
has slowed; for some CFCs a slight decline in their concentration is now
apparent. The phase-out of their manufacture in industrialised countries
by 1996 and in developing countries by 2006 as required by the 1992
amendments to the Montreal Protocol will ensure that the pro¬le of their
atmospheric concentration will continue to decline. However, because
of their long life in the atmosphere this decline will be slow; it will be a
century or more before their contribution to global warming is reduced
to a negligible amount.
The replacements for CFCs “ the hydrochloro-¬‚uorocarbons
(HCFCs), which are also greenhouse gases though less potent than the
CFCs “ are required to be phased out by 2030. It will probably be close to
that date before their atmospheric concentration stops rising and begins
to decline.
Because of the international agreements which now exist for control
of the production of the CFCs and many of the related species that
contribute to the greenhouse effect, for these gases the stabilisation of
atmospheric concentration required by the Climate Convention will in
due course be achieved.
Other replacements for CFCs are the hydro¬‚uorocarbons (HFCs),
which are greenhouse gases but not ozone-depleting. The controls of
the Montreal Protocol do not therefore apply and, as was mentioned in
Chapter 3, any substantial growth in HFCs needs to be evaluated along
with the other greenhouse gases. As we shall see in the next section, they
are included in the ˜basket™ of greenhouse gases addressed by the Kyoto
246 A strategy for action to slow and stabilise climate change

Table 10.1 Emissions targets (1990*“2008/2012) for greenhouse gases
under the Kyoto Protocol

Country Target (%)

EU-15**, Bulgaria, Czech Republic, Estonia, Latvia,
Lithuania, Romania, Slovakia, Slovenia, Switzerland
Canada, Hungary, Japan, Poland
New Zealand, Russian Federation, Ukraine 0

* Some economies in transition (EIT) countries have a baseline other than 1990.
** The ¬fteen countries of the European Union have agreed an average reduction;
changes for individual countries vary from ’28% for Luxembourg, ’21% for
Denmark and Germany to +25% for Greece and +27% for Portugal.
*** The USA has stated that it will not ratify the Protocol.

The Kyoto Protocol
At the ¬rst meeting after its entry into force held in Berlin in 1995,
the Parties to the Climate Convention (i.e. all the countries that had
rati¬ed it) decided that they needed to negotiate a more speci¬c and
quanti¬ed agreement than the Convention on its own provided. Because
of the principle in the Convention that industrialised countries should
take the lead, a Protocol was formulated that required commitments from
these countries (known as Annex I countries) for speci¬c quantitative
reductions in emissions (listed in Table 10.1) from their level in 1990


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