Annex I
A description of the formation and the work
of the IPCC based on a draft prepared for an Environmental Encyclopaedia
to be published by Wiley.
The Intergovernmental Panel on Climate Change:
Working Group I.
John Houghton, Co-chairman, Working Group I
(Scientific Assessment), Intergovernmental Panel on Climate Change
(IPCC).
FORMATION OF
THE IPCC
It has been known for well over 100 years that
the presence in the atmosphere of gases such as carbon dioxide
leads to a warming of the Earth's surface. In 1896, Sverre Arrhenius,
a Swedish chemist, first computed the amount of warming that would
occur should the amount of carbon dioxide in the atmosphere double.
In the 1960s, observations made by Charles Keeling from the Manna
Loa Observatory on Hawaii showed that atmospheric carbon dioxide
concentrations were increasing significantly. However, it was
not until the 1980s that it began to be generally recognised that
increased human activities involving the burning of fossil fuels
(coal, oil and gas) was resulting in a large increase in atmospheric
carbon dioxide and a probable doubling of its pre-industrial concentration
before the end of the 21st century. The possibility of serious
consequences to the world's climate was increasingly raised by
scientists and those with environmental concern.[2]
This is an example of global pollution—pollution by one
person locally that has global effects.
In 1988 an international conference was held
in Toronto which for the first time pressed for specific international
action to mitigate climate change. It was in that year too that
world leaders began to speak out about it; for instance, Mrs Thatcher
expressed her concern in a speech to the Royal Society of London
that was widely publicised. It was therefore timely that in 1988
a new scientific body to address the issue, the Intergovernmental
Panel on Climate Change (IPCC) was set up jointly by the World
Meteorological Organisation (WMO) and the United Nations Environment
Programme (UNEP). Bert Bolin from Sweden, a scientist with a distinguished
record of contributions to the science of climate, agreed to chair
the IPCC. Three Working Groups were established, WGI to address
the science of anthropogenic climate change, WGII to address the
impacts of climate change, and WGIII to address the policy options.
IPCC WGI has prepared comprehensive assessments of the science
of anthropogenic Climate Change in 1990 and 1995 together with
a number of other more limited assessments and technical reports.
A further comprehensive report is being prepared for publication
in 2001.
In its structure the IPCC followed closely the
structure of the Assessment Panels of the Montreal Protocol which
had been set up in 1987 by UNEP and WMO to address the problems
of the depletion of stratospheric ozone by CFCs and related chlorine
containing chemicals—another example of global pollution.
Through the negotiation of the Protocol, with its arrangements
for inputs from scientists and other experts, methods had begun
to be developed in the international community through which global
pollution problems could be addressed. Although this problem addressed
by the Montreal Protocol was a more limited one than that of global
climate change, especially in the range and size of the human
activities that contribute to it, it was appropriate that the
IPCC should build on this experience in addressing climate change
issues. The development within the IPCC of ways to involve large
numbers of scientists and of formal procedures for peer review
in turn influenced the ongoing work of the Assessment Panels of
the Montreal Protocol.
THE IPCC WGI 1990
REPORT[3]
It was agreed at the first meeting of the IPCC
that a new assessment of the whole issue of anthropogenic climate
change should be prepared. There had, of course, been assessments
before of the climate change issue, notably one published in 1986[4]
organised under the auspices of the Scientific Committee on Problems
of the Environment (SCOPE) of the International Council for Science
(ICSU) again under the chairmanship of Bert Bolin. The IPCC saw
its task as updating previous assessments but with a difference.
Previous assessments had involved relatively few of the world's
leading climate scientists. Because of the global nature of the
issue that brought with it a large measure of international concern,
the IPCC's ambition from the start was to involve as many representatives
as possible from the world scientific community in the new assessment.
To assist in the preparation of the WGI report,
a small Technical Support Unit was set up within the part of the
UK Meteorological Office at Bracknell which was concerned with
Climate Research. The report comprised 11 chapters totalling over
300 pages dealing with different components of the scientific
issue together with a Policymakers' Summary and an Executive Summary.
Twelve international workshops were held to address these different
components. One hundred and seventy scientists from 25 countries
contributed to the report either through participation in the
workshops or through written contributions. A further 200 scientists
were involved in the peer review of the draft report. The thorough
peer review played an important part in ensuring the achievement
of a high degree of consensus amongst the authors and reviewers
regarding the report's conclusions.
The Policymaker's Summary (20 pages) together
with its Executive Summary (two pages) were based on the conclusions
presented in the chapters and were prepared particularly to present
to those without a strong background in science a clear statement
of the status of scientific knowledge at the time and the associated
uncertainties. In preparing the first draft of the Policymakers'
Summary, the Lead Authors of the chapters were first involved;
it was then sent out for the same wide peer review as the main
report. A revised draft of the Summary was then discussed line
by line at a Plenary Meeting of the Working Group attended by
government delegates from 35 countries together with lead authors
from the chapters. The final wording was agreed at that meeting.
A flavour of the style and content of the report is given by the
first few paragraphs of the Executive Summary that read as follows:
We are certain of the following:
— there is a natural greenhouse effect
which already keeps the Earth warmer than it would otherwise be;
— emissions resulting from human activities
are substantially increasing the atmospheric concentrations of
the greenhouse gases: carbon dioxide, methane, chlorofluorocarbons
(CFCs) and nitrous oxide. These increases will enhance the greenhouse
effect, resulting on average in an additional warming of the Earth's
surface. The main greenhouse gas, water vapour, will increase
in response to global warming and further enhance it.
We calculate with confidence that:
— some gases are potentially more effective
than others at changing climate, and their relative effectiveness
can be estimated. Carbon dioxide has been responsible for over
half the enhanced greenhouse effect in the past, and is likely
to remain so in the future;
— atmospheric concentrations of the long-lived
gases (carbon dioxide, nitrous oxide and the CFCs) adjust only
slowly to changes in emissions. Continued emissions of these gases
at present rates would commit us to increased concentrations for
centuries ahead. The longer emissions continue to increase at
present day rates, the greater reductions would have to be for
concentrations to stabilise at a given level;
— the long-lived gases would require
immediate reductions in emissions from human activities of over
60 per cent to stabilise their concentrations at today's levels;
methane would require a 15 to 20 per cent reduction.
Based on current model results, we predict:
— under the IPCC Business-as-Usual
(Scenario A) emissions of greenhouse gases, a rate of increase
of global mean temperature during the next century of about 0.3oC
per decade (with an uncertainty range of 0.2oC to 0.5oC per decade);
this is greater than that seen over the past 10,000 years. This
will result in a likely increase in global mean temperature of
about 1oC above the present value by 2025 and 3oC before the end
of the next century. The rise will not be steady because of the
influence of other factors.
Later sections of the summary addressed the
scientific uncertainties and the question of the degree to which
anthropogenic climate change had been observed in the climate
record.
Over the period of the preparation of the IPCC
report, a significant change occurred in the attitudes of the
scientists involved. To begin with, many scientists felt that
the scientific uncertainty was too large for any useful statement
to be made regarding future climate change. However, increasingly
the scientists realised their responsibility to articulate carefully
and honestly the available knowledge. This responsibility seemed
all the more important because many individuals not possessing
much expert scientific knowledge were making forecasts of future
climate change—often of an extreme kind. Also, it was increasingly
recognised that there was enough certainty in the science to provide
meaningful information regarding the likely future provided that
the uncertainty was also fully explained.
CONSENSUS AMONGST
SCIENTISTS AND
BY GOVERNMENTS
Many of the world's leading scientists in the
field of climate and climate change contributed to the report.
Inevitably they came mostly from developed countries. However,
a significant number of contributors from developing countries
were also involved. That so many of the world's scientists contributed
or were involved in the review process meant that there was a
genuine feeling of ownership of the report by the world scientific
community.
The IPCC process led to a significant degree
of consensus. It is sometimes pointed out that "consensus"
amongst scientists is not necessarily a sign of scientific health;
argument and disagreement are seen to be more usual building blocks
of scientific advance. But the "consensus" achieved
by the IPCC is not complete agreement about everything. It is
agreement particularly about what we know and what we do not know—distinguishing
clearly those matters about which there is reasonable certainty
from those where there remains much uncertainty and where there
continues to be lively debate and disagreement. It is this limited
"consensus" which is reflected in the Executive Summary
of the 1990 IPCC Report which has been widely acclaimed for the
clarity and crispness of its presentation.
It was clear from an early stage that not only
was the scientific content of the assessment important but also
the way in which it was presented. Scientists left to themselves
do not always recognise what is relevant to policymakers or present
their material with the maximum clarity. Further, the presentation
of a scientific document can appear to a policymaker to convey
a political message even though none was intended.
It has therefore been helpful in the presentation
of the science of climate change to involve policymakers themselves
or their representatives in the formulation of the summary of
the reports. For instance they were full participants in the government
review process and in the Working Group Plenary Meeting which
agreed the wording of the report. The report was greatly improved
in its relevance and clarity through their participation. In addition
because governments participated in the process, they felt to
own the report.
The IPCC was therefore able to provide to the
Earth Summit at Rio in 1992 a clear assessment of the science
of climate change that was owned both by the world scientific
community and by governments. These characteristics were essential
to providing governments with the confidence to formulate and
sign the Framework Convention on Climate Change at that 1992 Conference
and to take appropriate action. They have continued to be essential
in the generation of subsequent reports which have provided input
to the on-going work of the FCC, for instance to the Kyoto Protocol
of 1997.
THE 1992, 1994 AND
1995 IPCC REPORTS
As soon as the 1990 report was complete, the
IPCC began work on further reports. In 1992, in time for the Earth
Summit, WGI produced a report updating what was known about greenhouse
gases[5],
their sources and sinks, and about observations and modelling
of climate change. In addition the 1992 report developed various
emission scenarios for the emissions of greenhouse gases over
the 21st Century based on a variety of assumptions regarding factors
such as world population, economic growth, availability of fossil
fuels etc.
The 1994 report updated the information and
analysis regarding the radiative forcing of the various greenhouse
gases[6].
Of particular importance was the new work carried out on the profiles
of emissions of carbon dioxide and other greenhouse gases which
would lead to the stabilisation of these gases in the atmosphere
at different levels of concentration.
By 1995, when the IPCC produced its second comprehensive
assessment[7],
five years after the first assessment in 1990, the community of
scientists involved with the IPCC had become substantially greater.
More scientists from more countries were involved both in the
report's preparation (about 480 scientists from more than 25 countries)
and in its review (over 500 from 40 countries). The participants
at the Plenary Meeting of Working Group I that approved the Summary
for Policymakers included 177 delegates from 96 countries, representatives
from 14 non-governmental organisations and 28 Lead Authors. Regarding
climate change over the next century and its likely impacts the
messages of the 1995 report were essentially the same as those
of the 1990 report. Some further detail had emerged during the
five years in between, especially regarding the likely contribution
to climate change from atmospheric aerosols—the fine particles
that are present in the atmosphere as a result of industrial activity.
Also, there was more confidence amongst scientists that the historical
increase in global average temperatures that has occurred since
wide-scale industrialization might be the result of anthropogenic
change. The WGI Plenary Meeting debated for a considerable time
how to express this somewhat greater scientific confidence in
the interpretation of the recent climate record—although
still surrounded by much uncertainty. A sentence carefully crafted
by the meeting was unanimously agreed by the delegates: "the
balance of evidence suggests a discernible human influence on
global climate."
THE FCCC AND
THE IPCC
The United Nations Framework Convention on Climate
Change (FCCC) signed by close to 160 countries at the Earth Summit
in Rio de Janeiro in June 1992 sets the context in which international
discussion regarding appropriate action can be pursued. The development
of the Convention's agenda clearly requires continuous scientific
and technical input. The Conference of the Parties (COP) to the
FCCC has set up a Subsidiary Body for Science and Technological
Advice (SUBSTA) to organise this input. The IPCC is working closely
with SUBSTA through a Joint Working Group (JWG) to ensure that
IPCC assessments are geared to provide the detailed scientific
and technical input required.
The objective of the FCCC is contained in Article
2. It recognises the need to prevent continued change of the climate.
It reads as follows:
"The ultimate objective of this Convention
and any related legal instruments that the Conference of the Parties
may adopt is to achieve, in accordance with the relevant provisions
of the Convention, stabilization of greenhouse gas concentrations
in the atmosphere at a level that would prevent dangerous anthropogenic
interference with the climate system. Such a level should be achieved
within a time frame sufficient 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."
The IPCC has been at pains to explain that what
constitutes "dangerous" is a policy not a scientific
decision. But the need to make such policy decisions immediately
raises many scientific and technical questions. For instance,
what carbon dioxide emission profiles will lead to stabilisation
of atmospheric concentration and by when? What effect will current
proposed emission limitations by developed countries have on atmospheric
concentrations? What technologies, policies and measures might
be available for mitigating climate change? How vulnerable are
different regions of the world to possible climate change? To
assist in answering these questions the IPCC has produced a series
of Technical Papers addressing the detail of some of the issues
involved.
An issue which has been highlighted by the third
session of the COP at Kyoto in 1997 is that of the contributions
which are made by deforestation, aforestation, reforestation and
changes in land use to the sources or sinks of greenhouse gases,
especially of carbon dioxide. This is an area where what is meant
by different human activities (eg de-, a-, or re-forestation)
requires very careful definition, where there is much scientific
uncertainty and where there are large possibilities for the propagation
of perverse incentives. The IPCC is already very involved in this
area through its work on the development of detailed guidelines[8]
for the production of national inventories of greenhouse gases
which include both sources and sinks. It is the IPCC Guidelines
to which the Kyoto Protocol refers. A Special Report on Land Use
and Forestry addresses these issues[9].
THE FUTURE
WORK OF
THE IPCC
Preparation is now starting for a third comprehensive
assessment report to be completed in 2001 that will take into
account the large growth in research in both the natural sciences
and the social sciences in topics related to climate change, its
impacts and its mitigation. In carrying out this assessment the
IPCC will ensure that it is relevant to the policy needs of the
FCCC and will also ensure that the process of assessment continues
to be open, transparent and rigorous and continues to involve
as many in the world scientific community as possible.
The question is often asked as to whether the
IPCC provides a pattern or a model for providing the means for
scientists from all disciplines to provide input to policy determination
in other areas of concern. The elements which we have mentioned
which have been critical to the success of the IPCC have been
those of: (1) ensuring the widest possible participation by experts
from all relevant disciplines; (2) ensuring a clear separation
between scientific assessment and policy determination and (3)
through the close involvement of the expert community, of governments
and, more recently, of relevant industry, ensuring wide ownership
not only by the community of experts but also by those who have
a stake in the policy process. Although anthropogenic climate
change is perhaps the largest and most complex problem concerned
with the global environment that we face, it is not unique. Models
similar to that of the IPCC with its essential elements could
be applied elsewhere. The development of the work of the IPCC
has demonstrated the enormous capacity for the international community
to work together towards the common aims of care for humanity
and care for the environment and provides encouragement in the
belief that problems as complex as that of climate change are
capable of solution.
2 A comprehensive account of Global Warming and Climate
Change can be found in, John Houghton, "Global Warming:
the Complete Briefing" second edition, Cambridge University
Press, 1997. Back
3
Climate change, the IPCC Scientific Assessment, eds JT Houghton,
GJ Jenkins and JJ Ephraums, Cambridge University Press, 1990. Back
4
SCOPE 29, The Greenhouse Effect, Climatic Change and Ecosystems,
eds Bert Bolin, Bo Doos, Jill Jager and Richard Warrick, John
Willey 1986. Back
5
Climate Change 1992: the Supplementary Report to the IPCC Assessment,
eds J T Houghton, B A Callander and S K Varney, CUP, 1992. Back
6
Climate Change 1994: Radiative Forcing of Climate Change and
an Evaluation of the IPCC IS92 Scenarios, eds J T Houghton, L
G Meira Filho, J Bruce, Hoesung Lee, B A Callander, E Haites,
N Harris and K Maskell, CUP, 1996. Back
7
Climate Change 1995: the Science of Climate Change, eds J T Houghton,
L G Meira Filho, N Harris, A Kattenberg and K Maskell, CUP, 1996;
Climate Change 1995: Impacts, Adaptation and Mitigation of Climate
Change, eds R T Watson, M C Zinowera and R H Moss, CUP, 1996;
Climate Change 1995: Economic and Social Dimensions of Climate
Change, eds J Bruce, Hoesung Lee and E Haites, CUP, 1996. Back
8
IPCC Guidelines for National Greenhouse Gas Inventories. IPCC
Secretariat, World Meteorological Organisation, Geneva, 1995. Back
9
IPCC Special Report on Land Use Change and Forestry due for completion
in May 2000-reference to completed in proof. Back
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