Global Environmental Change

Issues in Environmental Science and Technology

By R.E. Hester, R.M. Harrison

The Royal Society of Chemistry

Copyright © 2002 The Royal Society of Chemistry
All rights reserved.
ISBN: 978-0-85404-280-7

Contents

An Overview of the Intergovernmental Panel on Climate Change (IPCC) and Its Process of Science Assessment Sir John Houghton, 1,
A Perspective on Global Air Pollution Problems Johan C. I. Kuylenstierna, W. Kevin Hicks and Michael J. Chadwick, 21,
Influence of Climate Variability and Change on the Structure, Dynamics and Exploitation of Marine Ecosystems Manuel Barange, 57,
Rising Sea Levels: Potential Impacts and Responses Robert J. Nicholls, 83,
Climate Change, Global Food Supply and Risk of Hunger Martin L. Parry and Matthew T. J. Livermore, 109,
Global Environmental Changes and Human Health Michael V. Ahern and Anthony J. McMichael, 139,
Corporate Environmental Performance Frans Berkhout, 161,
Subject Index, 185,

CHAPTER 1

An Overview of the Intergovernmental Panel on Climate Change (IPCC) and Its Process of Science Assessment

SIR JOHN HOUGHTON

1 Background

It has been known for about 175 years that the presence in the atmosphere of ‘greenhouse gases’ such as carbon dioxide that absorb in the infrared part of the spectrum leads to a warming of the Earth’s surface through the ‘greenhouse’ effect. The first quantitative calculation of the effect on the atmosphere of increased carbon dioxide concentrations was made by the Swedish scientist Svante Arrhenius in 1896. In the 1960s, Charles Keeling and his colleagues began a regular series of accurate observations of atmospheric carbon dioxide concentration from the Mauna Loa Observatory in Hawaii. These showed increasing values as a result of human activities, mainly the burning of fossil fuels. By the 1980s, as the rate of increase of carbon dioxide concentration became larger, the possible impact on the global climate became a matter of concern to politicians as well as scientists. The report of a scientific meeting held at Villach, Austria in 1985 (SCOPE 29,1986) under the auspices of the Scientific Committee on Problems of the Environment (SCOPE) of the International Council of Scientific Unions (ICSU) began to alert governments and the public at large to the potential seriousness of the issue. Estimates were made that the carbon dioxide concentration could double before the end of the 21st century. In 1986, three international bodies, the World Meteorological Organisation (WMO), the United Nations Environment Programme (UNEP) and the International Council of Scientific Unions (ICSU), who had co-sponsored the Villach conference, formed the Advisory Group on Greenhouse Gases (AGGG), a small international committee with responsibility for assessing the available scientific information about the increase of greenhouse gases in the atmosphere and the likely impact.

2 Formation of the IPCC

What was new about the problem of global warming’ (as the climate change due to the increase of gases began to be called) was that it is an example of global pollution or pollution on the global scale, i.e. pollution emitted by one person locally that has global effects. This can be compared with pollution due to human activities on a local scale, of air, water or land that has been around for a very long time. The other example of global pollution which was recognized about the same time is the damage to the ozone layer in the stratosphere that results from the release of small quantities of chemicals containing chlorine (e.g. the chloro-fiuorocarbons or CFCs).

The existence of global pollution requires global solutions, i.e. solutions that are organized on a global scale. In the late 1980s, therefore, as political concern began to be expressed about the possibility of deleterious climate change, the organization of that concern was international, as indeed had been the work of the scientists on which the political concern was based. In June of 1988 an international conference was staged 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 publicized.

It was therefore timely that in 1988 a new international scientific body to address the issue, the 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 and WGIII to address the policy options. I was appointed chairman of WGI and I will illustrate from my experience of that Working Group the work of the IPCC and how, through the IPCC, scientists have been able to assist in the determination of policy.

The establishment of the IPCC followed closely that of the Montreal Protocol which had been set up in the previous year, 1987, by UNEP and WMO to address the problem of the depletion of stratospheric ozone by CFCs and related chlorine-containing chemicals. 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. However, 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 arena through which problems of global pollution could be addressed. It was therefore appropriate that the IPCC should build on this experience. The development within the IPCC of ways to involve large numbers of scientists and of formal procedures for peer review in turn influenced the on-going work of the Assessment Panels of the Montreal Protocol.

3 The IPCC 1990 Report

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 that resulting from the Villach conference (SCOPE 29), again under the chairmanship of Bert Bolin as mentioned in the introduction. 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 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 eleven 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 assisted in achieving a high degree of consensus amongst the authors and reviewers regarding the report’s conclusions.

The Policymakers’ Summary (20 pages) together with its Executive Summary (2 pages) was based on the conclusions presented in the chapters and was 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 of 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, and the final wording 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 which 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 stabilize at a given level.

• the long-lived gases would require immediate reductions in emissions from human activities of over 60% to stabilize their concentrations at today’s levels; methane would require a 15-20% 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 0.3 °C per decade (with an uncertainty range of 0.2 °C to 0.5 °C 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 1 °C above the present value by 2025 and 3 °C 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 there was a strong feeling, particularly amongst some scientists, that the scientific uncertainty was too large for any useful statement to be made regarding future climate change. However, gradually we all realized our responsibility to articulate carefully and honestly the knowledge which is available, distinguishing clearly between what could be said with a good degree of certainty and the areas where the uncertainty is large. After all, there were many not expert in the science who felt few inhibitions about making forecasts of future climate change – often of an extreme kind. Also we increasingly recognized that there was enough certainty in the science to provide meaningful information regarding the likely future, provided that the uncertainty was also fully explained.

4 Ownership by Scientists and by Governments

Many of the world’s leading scientists involved with the understanding 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 recognize 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, for instance through the selection of the particular material employed.

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 the large number of governments which had a part in the process felt ownership of 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 to 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 FCCC, for instance to the Kyoto Protocol of 1997.

5 The Science Policy Interface

The work of the IPCC illustrates the following five important features which I believe should characterize the scientific assessments that form an input to policy making.

The first has already been mentioned, namely the separation of what is known with reasonable certainty from what is unknown or very uncertain. All statements from scientists that have policy implications should make this distinction and should describe and quantify the uncertainty as fully as possible.

Secondly, it has been important for its continued credibility that the IPCC has confined itself in its reports and statements to scientific information and has avoided making judgements or giving advice about policy. Often in the past these areas have been confused. The scientific information must, of course, be comprehensive and must include input from all relevant scientific disciplines, including the social sciences. But in the formulation and presentation of policy options or in making policy judgements the scientific input must be clearly distinguished from the policy judgements and decisions. The importance in environmental decision making of this separation of scientific and other expert assessment from policy judgement is argued in a recent report of the Royal Commission on Environmental Pollution in the UK.

Thirdly, all parts of the assessment process need to be completely open and transparent. IPCC documents including early drafts and review comments have been freely and widely available – adding much to the credibility of the process and its conclusions.

Fourthly, the purpose of an assessment is to take account of all scientific data and all genuine scientific opinion and to elucidate and articulate the best scientific interpretation and conclusions from the information available. Scientific assessments must not start with preconceived assumptions and no compromises must be made to meet any personal or political agendas. A thorough and wide peer review process helps to guarantee the honesty and comprehensiveness of the process.

Fifthly, the scientific information must be integrated in a thoroughly balanced way. The amount of data available concerning climate and climate change is very large and it is easy to select data that fits in with a wide range of preconceived ideas or assumptions. However, by involving so many scientists from the complete range of relevant disciplines it has been possible to develop a balanced integration of the information in a way that has commanded general acceptance.

6 IPCC’s Work in Science Applications and in Social Sciences

Working Groups II and III of IPCC have been concerned with the impacts of climate change and adaptation to and mitigation of climate change. Consideration of these has involved not only natural scientists but also experts from many areas of social science, especially economics. As with WGI the aim of the other Working Groups has been to involve scientists with a wide range of expertise and from as many countries as possible. This has been less easy in the social sciences than in the natural sciences where, especially in a subject like the science of climate, there has been a long tradition of scientists working together across national boundaries. However, through the stimulation of the IPCC a substantial international community of social scientists has been brought together to address the variety of problems exposed by the climate change issue.

In this area, as in natural science, the IPCC has stressed the importance of separating the scientific analysis from policy judgements. But it is clearly more difficult when dealing with economic or political analysis to make this separation convincing. Because of this some have argued that the IPCC should not become engaged in analysis in these social science areas. The IPCC has consistently refused to accept that argument, believing that a great deal of useful technical supporting work needs to be done in providing analyses of some of the economic or political options which might be taken up in response to the impact of climate change. Further, it is a great advantage if this work is pursued outside government agencies or other political institutions. Such analyses are essential input for international negotiations regarding the options and essential preparation for decision making.

(Continues…)Excerpted from Global Environmental Change by R.E. Hester, R.M. Harrison. Copyright © 2002 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
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