House of Commons - Science and Technology

Select Committee on Science and Technology Third Report

THIRD REPORT

The Science and Technology Committee has agreed to the following Report:—

SCIENTIFIC ADVISORY SYSTEM: SCIENTIFIC ADVICE ON CLIMATE CHANGE

1. As the fourth, and final, case study in our inquiry into the Scientific Advisory System we have examined the scientific advice which the Government receives on climate change. [7] We launched this case study in November 1999 with the intention of identifying:

(B) what critical appraisal there has been of models predicting climate change, increasing concentrations of carbon dioxide, and other potential drivers; and

(C) the degree of Government agreement with scientists in relevant specialisations regarding accepted explanations of climate change."[8]

It has not been our purpose to inquire whether or not there is global warning: we have taken as given that there is an upward trend in the temperature of the earth, and that carbon dioxide concentrations in the atmosphere are, and have been, increasing. Nor has it been our purpose to inquire into the cause of global warming, and whether, or to what extent, it is man-made. We acknowledge the work that has been done by the Environment, Transport and Regional Affairs Committee and by the Environmental Audit Committee in examining the Government's response to climate change.[9] We also acknowledge the work of our predecessor Committee on research into climate change in its inquiry into the Natural Environment Research Council in 1996-97.[10] In this Report we examine how the Government obtains scientific advice on climate change and whether it is authoritative and comprehensive. We also examine the national research programme which informs this scientific advice; and we consider how policymakers deal with scientific uncertainty.

2. During this case study we have received sixteen memoranda from a range of organisations. We have held three sessions of oral evidence. The first, on 15 March 2000, was with Sir John Houghton, former Chief Executive of the Meteorological Office and now co-Chair of Working Group I of the Intergovernmental Panel on Climate Change (IPCC). The second, on 13 December 2000, was with three climatologists: Professor David Q Bowen, Professor of Quaternary Geology at the Department of Earth Sciences, Cardiff University; Professor Alan O'Neill, Director of the Natural Environment Research Council (NERC) Centre for Global Atmospheric Modelling at the University of Reading; and Dr Simon Shackley, from the Manchester School of Management at the University of Manchester Institute of Science and Technology (UMIST), and also a programme manager in the new Tyndall Centre. The third, on 20 December 2000, was with the Minister of the Environment, the Rt Hon Michael Meacher MP; Dr David Fisk, Chief Scientist at the Department of the Environment, Transport and the Regions (DETR); and Mr David Warrilow, Head of Science Policy in the DETR's Global Atmosphere Division. We are grateful to all those who provided evidence, and to our four specialist advisers: Professor Derek Burke, formerly Vice-Chancellor of the University of East Anglia; Professor Michael Elves, formerly Director of the Office of Scientific and Educational Affairs, Glaxo Wellcome plc; Professor Peter Liss, Professor of Environmental Sciences at the University of East Anglia; and Professor John Pyle, Director of the Centre for Atmospheric Science, Cambridge University.

Climate change

3. Climate change - which, following IPCC usage, we take to mean any change in climate over time, whether due to natural variability or as a result of human activity - is a major issue confronting policy makers, yet it is an area of considerable scientific uncertainty. It gives rise to a range of policy questions, including: what position the UK should take in international negotiations on emission reductions, and how it should respond to the international agreements reached; what fiscal measures might most effectively be taken to discourage emissions and to encourage the use of, and investment in, alternative, renewable, energy; how it should manage the effects of severe weather and rising sea level, in terms of flood protection and coastal defence; how transport policy might be affected by emission reduction targets; and how agriculture should respond to changing climate. In all these areas Government requires scientific advice.

THE SCIENTIFIC BACKGROUND

4. It is generally agreed that global warming is taking place. (The global average surface temperature increased over the 20th Century by around 0.6º C.[11] ) There is some disagreement, however, about the extent to which this global warming is anthropogenic (man-made). There is agreement that there are increasing concentrations of "greenhouse gases"- largely carbon dioxide, nitrous oxide, methane and chlorofluorocarbons (CFCs) - in the Earth's atmosphere, but there is uncertainty about the extent to which the "greenhouse effect" (by which the increasing concentrations of these gases trap solar radiation, leading to global warming) accounts for the observed temperature change. There is agreement that the climate can change naturally (through variation in solar output, or the release of volcanic dust, for example), and that there have been marked natural climate changes in the past, but there is uncertainty regarding the extent to which the recent increase in temperatures might be caused by such natural factors. While climate models are becoming increasingly sophisticated and accurate at prediction, there is still uncertainty about the "feedback" effects of clouds, of water vapour, of ocean circulation and of forests. There is uncertainty about the consequences of climate change, and about the local impacts of the predicted increase in sea level and in more extreme weather. There is agreement that polar ice is melting, but uncertainty as to how much, as well as to the possible future effect of this on ocean currents. There is uncertainty too about the effectiveness of possible mitigation strategies: about the impact of "carbon sinks" in sequestering carbon from the atmosphere, and in retaining it; and about the speed with which fuel emission reductions would impact on greenhouse gas concentrations.

THE POLITICAL BACKGROUND

5. Climate change is a global issue which needs to be addressed by international agreement. International negotiations, in which the UK plays a leading role, have been proceeding since the 1980s. In 1988 the World Meteorological Organisation and the United Nations Environment Programme jointly set up the Intergovernmental Panel on Climate Change (IPCC) in order to provide authoritative scientific assessment of the evidence for human-induced climate change.[12] The IPCC completed its First Assessment Report in 1990, and this contributed to the negotiations which led to the adoption of the United Nations Framework Convention on Climate Change (UNFCCC) at the Earth Summit in Rio de Janeiro in June 1992. The IPCC completed its Second Assessment Report in 1995, concluding that "The balance of evidence suggests a discernible human influence on global climate".[13] This was a key input to the negotiations which led to the adoption of the Kyoto Protocol to the Framework Convention on Climate Change at the Third Conference of Parties meeting in Kyoto in December 1997, which agreed targets for reduction of emissions of greenhouse gases by developed countries.[14] The Sixth Conference of Parties (COP6)[15] met at the Hague in November 2000, and failed to gain agreement on how to implement the reductions agreed at Kyoto. The negotiations are expected to reconvene in Bonn in May 2001; and COP7 will meet in Marrakech in October 2001. The IPCC's Third Assessment Report is to be released later this year: the scientific assessment report of the IPCC's Working Group I (WG I) was accepted at a meeting of IPCC member governments in Shanghai in January 2001. The "Summary for Policymakers" approved at that meeting concludes that "most of the warming observed over the last 50 years is attributable to human activities".[16]

Sources of scientific advice to Government

THE IPCC

6. According to the DETR's memorandum, the principal source of scientific advice to Government on climate change is the reports of the IPCC.[17] The IPCC works through three Working Groups. Working Group I assesses the science of climate change; Working Group II assesses the socio-economic and natural impacts of climate change and the options for adapting to it; and Working Group III assesses the options for limiting greenhouse gas emissions and otherwise mitigating climate change. WG I involves many hundreds of climatologists from around the world, covering a wide range of disciplines and a variety of opinions. WG I's reports are very lengthy documents, including authored chapters, a technical summary and a shorter summary for policymakers. The reports are subject to extended peer review, and to very widespread scrutiny before publication by scientists and by Governments.[18] In Dr Shackley's words, "the Policymakers' Summary and Technical Summary of the IPCC reports are amongst the most scrutinised scientific documents ever produced".[19] It is largely because its process of assessment is, in Sir John Houghton's words, "open, transparent and rigorous"[20] that the IPCC's reports command such general respect.

7. It is significant that the IPCC is an intergovernmental body. Before its reports are published they are scrutinised in detail by representatives of the member governments as well as scientists. This has the advantage that governments accept the conclusions of the published reports, and in a sense take "ownership" of them. It also means that governments - the UK Government included - are unusually close to the latest and most authoritative scientific opinion world-wide. On the other hand, the involvement of governments makes the IPCC a highly political organisation. While Sir John Houghton assured us that the IPCC stuck "very firmly to a presentation of the science, not the political interpretation of that science"[21], Dr Shackley's description of the WG I plenary meeting in Madrid in 1995 indicates that the IPCC's negotiations have a distinctly political quality.[22] There must be a danger that, in bringing together such diverse and conflicting interests to reach a consensus, the "lowest common denominator" view will prevail. It is remarkable - and to the great credit of the scientists involved - that the IPCC's reports are incisive.

8. One advantage of the IPCC's political framework is that it ensures that the prevailing anthropogenic view of climate change is thoroughly tested, and that alternative views are properly aired. For example, oil-producing members of the IPCC have a clear interest in ensuring that the view that fossil fuels are to blame for climate change is subject to close scrutiny, that uncertainty is exposed and that alternative natural causes are properly explored. While the majority of scientists at the IPCC take the view that climate change is at least partly man-made, it includes some who hold dissenting views. For example, Professor Richard Lindzen from the Massachusetts Institute of Technology (who is a well known sceptical voice on the extent of climate change as predicted from models) is one of the lead authors of the Third Assessment Report.[23] The IPCC's full reports reflect these differences of views, though the policymakers' summary gives only the consensus position. Dr Shackley told us that "within the full report there is a whole wealth of viewpoints and uncertainties that do not always find themselves in the policymakers' summary".[24] But, of course, most policymakers will read no further than the policymakers' summary. The Minister told us that, while he had a copy of the full Second Assessment Report, and had dipped into it, his reading was largely confined to the summaries, because of the pressure of time.[25] The summaries of the IPCC's assessment reports are concise and useful documents, and present the consensus view of climate change in appropriately cautious terms. However, focusing attention on these summaries may limit the IPCC's effectiveness in communicating to policymakers the extent of the uncertainties of climate change science.

9. That said, there is no doubt that the IPCC is generally held in very high regard. It has been suggested that the IPCC could be a model for scientific advice on other issues of complexity and global concern. For example, at the OECD Edinburgh Conference on the scientific and health aspects of genetically modified foods in February 2000, it was proposed that the IPCC model could be used, in an adapted form, to build a scientific consensus on genetically modified (GM) organisms.[26] The Minister told us that he would be happy to promote the IPCC model internationally, though in his view there was much more scientific controversy about GM organisms than there was about climate change.[27] Another area for building international scientific consensus, and one requiring action world-wide, is ocean pollution. We recommend that the Government actively promote the IPCC model in other policy areas of global significance in which there is considerable scientific uncertainty.

THE HADLEY CENTRE

10. Between IPCC assessments, the Government appears to rely for advice on climate change predominantly on the Hadley Centre of the Meteorological Office.[28] The Hadley Centre for Climate Prediction and Research was set up in 1990, adjacent to, and a part of, the Met Office at Bracknell, to provide Government with up-to-date advice on all aspects of climate change, particularly in order to inform the UNFCCC negotiations.[29] The Hadley Centre's work is based on the use of computer models of the atmosphere, ocean, biosphere, cryosphere and land surface to predict climate change.

11. While global climate models[30] are generally agreed to be an essential tool in gaining understanding of climate change, some scientists are sceptical of the ability of models accurately to predict climate change.[31] Sir John Houghton acknowledged that "because of the complexities of the climate system, models are inadequate in various respects and have to be carefully appraised".[32] Global climate models, which incorporate information about oceanic as well as atmospheric circulations, are becoming increasingly sophisticated. They are increasingly effective in simulating feedback mechanisms, in reproducing past climates, and in allowing local effects to be identified. The DETR commissions independent validation of the Hadley Centre's models by the Climatic Research Unit at the University of East Anglia.[33] The Hadley Centre's latest global climate model was ranked best overall in simulation of the current climate in a recent international comparison by the Coupled Model Intercomparison Project.[34]

12. Some of those providing evidence to us suggest that, while the Hadley Centre is very expert in climate modelling and in the physics and mathematics of climate change, it lacks expertise in other disciplines, notably the biological sciences.[35] They suggest that it is ill-equipped, therefore, to advise the Government on many aspects of climate change, which are of considerable importance to policymakers (for example, on the performance of carbon sinks, which was a major focus of the COP6 negotiations last November). The DETR acknowledges that the Hadley Centre's in-house expertise is largely in maths and physics, though it has a few staff with degrees in environmental science, geography and related disciplines. The DETR's view is that it is more effective for the Hadley Centre to work closely with biologists and ecologists at other institutes (notably the NERC Centre for Ecology and Hydrology).[36] Dr Fisk argued that "if we had simply made the Hadley Centre the centre of everything it would become unstable and not open to the broader challenge of the scientific community".[37] We agree that it is important for the Hadley Centre to work closely with other specialist institutes, and that it should continue to concentrate on its core strengths. However, we strongly suggest that it might benefit from more in-house staff with expertise outside meteorology, including the biological sciences.

13. Some of the evidence we have received suggests that the Government is over-reliant on the Hadley Centre, and therefore on climate models, and pays insufficient attention to alternative sources of advice.[38] Dr Shackley estimated that the Government got perhaps 90% of its advice from the Hadley Centre.[39] Critics suggest that the Hadley Centre is insufficiently independent, given that it is directly government-funded[40] and part of a government agency. The Minister, not surprisingly, did not consider that the Government was "unduly dependent" on the Hadley Centre nor that there was "an over-cosy relationship" between the Hadley Centre and Government.[41] He pointed out that all the Hadley Centre's research is published and open to external scrutiny which included a rigorous peer review process.[42] The work of the Hadley Centre is monitored by an independent Science Review Group of UK experts, and its models are subjected to independent validation by the Climatic Research Unit at the University of East Anglia. The Hadley Centre was subject to a major review five years after it was established, and is currently undergoing a ten year review, which includes a review of its science by a panel of international experts, as well as a review of its finance and management.[43] We recommend that the results of the 10 year review of the Hadley Centre be published as soon as it is completed.

14. The Hadley Centre's closeness to Government has advantages, of which perhaps the most obvious is that communication of scientific advice to policymakers is swift and effective. It is at least partly because of the unusually close relationship between DETR policymakers and scientists at the Hadley Centre that the UK Government has been at the forefront of international action on climate change. We have no evidence to suggest that the Hadley Centre's advice is compromised by its closeness to Government, or that it acts in any way differently from an independent research institution. Nevertheless, it is important for public confidence that scientific advice to Government on climate change, as in other areas, should be seen to be independent and not dependent solely on the Hadley Centre.

15. The Hadley Centre is not just close to Government; it is also very close to the IPCC. The WG I's Technical Support Group (effectively its secretariat) is located at the Hadley Centre; and, further, the WG I is co-chaired by Sir John Houghton, chief executive of the Met Office from 1983 to1988. In many ways this close connection is admirable, and is an indication of the high regard in which the Hadley Centre is held internationally. Yet, there must be concern whether the Hadley Centre is able to offer Government critical assessment of the IPCC reports, because it is so closely involved in the IPCC process.

OTHER SOURCES OF ADVICE

16. The DETR points out that on climate change it is not just advised by the Hadley Centre. On the impacts of climate change, it is advised by the Climatic Research Unit at the University of East Anglia, by the Environmental Change Institute at Oxford University, and by NERC's Centre for Ecology and Hydrology.[44] It is also advised by NERC's Southampton Oceanography Centre.[45] Indeed, Dr Fisk maintained that "one of the strengths of the Department's programme on climate change is that we have not focused all our funding on the Hadley Centre".[46] We welcome this diversity of advice. As the Minister stated, "to rely exclusively on one body would be unwise in an area which is so multifaceted".[47]

17. A new source of advice on the impact of climate change is the Tyndall Centre for Climate Change Research which opened in November 2000.[48] The Centre is based at the University of East Anglia in Norwich with regional offices at UMIST in Manchester and at the University of Southampton. It brings together climate scientists, economists, social scientists and engineers from nine higher education and research institutions, to assess the implications of climate change and to develop sustainable solutions.[49] It was established by NERC, together with the Engineering and Physical Sciences Research Council (EPSRC) and the Economic and Social Research Council (ESRC), with £10 million funding over five years.[50] We note that one of the requirements on the Centre will be to create mechanisms for turning its research findings into scientific advice to government.[51] If the Tyndall Centre proves its worth, we recommend that its funding be put on a more secure and long-term footing, since climate change issues will be with us for many years yet.

OTHER DISCIPLINES AND DISSIDENT VOICES

18. A key question in our inquiry has been whether the Government has been fully advised of potential alternative explanations of climate change; and specifically, whether it is sufficiently aware of dissident voices who maintain that the uncertainties are too great to conclude that climate change is to a significant extent man-made. The Minister was confident that Government was obtaining a full range of advice: "this is an area where the quality and range of advice which I am getting is extremely high. I do not have suspicions about what I am not being told, as I do occasionally in other areas.".[52] On the other hand, there appears to be a sense among some scientists, particularly geologists and biologists, that they are excluded from what might be termed the Hadley Centre and IPCC coterie who advise the Government. The Geological Society of London questioned the extent to which Government seeks the views of a broad range of scientists in addition to the advice given by its appointed advisers and consultants.[53] The Government must ensure that it receives advice on climate change from all relevant scientific disciplines.

19. The Government must also ensure that it is aware of the views of independent scientists, who may dissent from the consensus view of climate change. While we have no wish to throw doubt on the strong consensus that climate change is man-made, we believe that, in Dr Shackley's words, "it is vital that alternative explanations are constantly scrutinised and encouraged into the debate".[54] Dissidents sometimes turn out to be right in at least some of what they say. Professor Bowen, though cautious in his words, strongly conveyed his belief that dissenting views were not being sufficiently heard by Government, or by the IPCC.[55] As we have seen, the range of views explored in the full reports of the IPCC are not reflected in the policymakers' summaries. We believe that there needs to be some rethinking of the mechanisms by which Government gets its advice. Clear and transparent channels should be available through which scientists who hold dissenting views can readily communicate their ideas to policymakers and can have confidence that they have been heard.

20. A way for the Government to ensure that it is aware of all currents of advice on climate change - and to demonstrate that it is not overly dependent on the Hadley Centre - would be to create an advisory committee of eminent scientists drawn from a wide range of interests and disciplines. In general, we believe that there are too many advisory committees in existence, and that more should be created only if there is a clear need and obvious benefit. In the case of climate change, we believe that such a committee would be justified. It should be made clear in its terms of reference that its role is not to duplicate the work of the IPCC, but to advise Government on UK policy on climate change. We envisage that the new committee should have a different role from the former Inter-Agency Committee on Global Environmental Change or its replacement, the Global Environmental Change Committee, which we discuss in paragraph 23 below, being advisory rather than co-ordinating in purpose (though by bringing scientists of different disciplines together, it would clearly assist co-ordination). It could usefully be asked to comment on policy options as well as to advise on the science. It should be clearly independent of Government, and be chaired by an academic scientist. In order to underline this independence, and to build on the work that the Royal Society is already doing in this field, it might be that the new committee could be jointly established by Government and by the Royal Society, perhaps along the US National Academy of Science/National Research Council model. Accordingly, we recommend that the Government establish a new independent advisory committee to advise Government on the science of climate change and on policy options.

The research base

21. As the Institute of Biology states, "scientific advice can change as more questions are asked and detailed information provided by researchers".[56] It is the role of the Research Councils to ensure that the UK science base is robust enough to be able to answer questions from policymakers on issues of topical importance. NERC has the lead role in promoting climate research, undertaking or funding a wide range of programmes studying past and natural climate change, as well as anthropogenic climate change and its impacts.[57]. The ESRC has funded two major programmes (the Global Environmental Change (GEC) Programme based at the University of Sussex, and the Centre for Social and Economic Research on the Global Environment (CSERGE) at the University of East Anglia and University College London) as well as individual research grants.[58] The EPSRC is involved with NERC and ESRC in funding the new Tyndall Centre, as part of its £30 million a year commitment to sustainable development. The Biotechnology and Biological Sciences Research Council (BBSRC) has funded research, focusing on the effects of climate change on microbes, plants and animals, and its impact on agriculture.[59] According to BBSRC's memorandum, the Research Councils seek to co-ordinate their work through a Cross-Council Group on Climate Change (CCGCC), but we understand that it was set up in 1998 and has not met since 1999.[60] As Sir John Houghton told us, "putting ... things together into a coherent and sensible national research programme is still a difficulty, because different subjects are addressed in different ways, by different Research Councils".[61] There is also concern that the implications of research findings may not always be communicated effectively to policymakers.[62] The recently established Royal Society Global Environmental Research Committee has made a promising start in representing the views of the academic community and in indicating research directions which need to be pursued.

22. In addition to the research supported by the Research Councils, in their own centres and at universities, Government Departments commission research directly. For example, the DETR funds the UK Climate Impacts Programme, based at the Environmental Change Institute at Oxford University.[63] The Minister suggested that the Research Councils dealt with the "strategic science", while the DETR dealt with "policy-driven policy-relevant questions"[64], but the division of responsibility is not entirely clear. There is some concern that Government Departments pursue independent research agenda, without sufficient co-ordination with other Departments or the Research Councils. According to the BBSRC, "Government Departments tend to commission their own studies and it is unclear how much cross-fertilisation there is".[65]

23. This concern has been heightened by the winding up of the Inter-Agency Committee on Global Environmental Change (IACGEC), which until recently was responsible for "high level co-ordination of UK research on climate change and other global environmental issues".[66] The IACGEC, which was chaired by Professor Sir Richard Southwood, Professor of Zoology at Oxford University, has been replaced by the Global Environmental Change Committee, chaired by Dr Fisk, the Chief Scientist at the DETR, apparently on the advice of the Chief Scientific Adviser.[67] Dr Fisk told us that it was thought appropriate to replace IACGEC with something less bureaucratic and more directed to organising coherence with policy outcomes.[68] We can see no reason for more than one committee co-ordinating research on climate change, and suggest that the new Global Environmental Change Committee be given a chance to prove itself in this role. We envisage that this co-ordinating committee would have an administrative role, overseeing the co-ordination of research and research funding, quite different from the advisory role of the independent committee we recommend in paragraph 20 above.

24. Research on climate change is, of course, being carried out world-wide. The UK is a major contributor to a number of international research activities within the World Climate Research Programme and the International Geosphere-Biosphere Programme.[69] Co-ordination of international research in this area is clearly vital, to ensure both cost-effectiveness and cross-fertilisation of ideas. The Research Councils co-operate internationally through the International Group of Funding Agencies.[70] The IPCC process plays a useful part in ensuring that scientists are aware of work carried out in other countries.

25. Witnesses have suggested that there are some areas of importance to climate change which are at present under-researched. The Institute of Biology argues that research on ecosystem function, and on the response of ecosystems to environmental changes, has been neglected; and, in particular, that more research is needed on the way carbon is sequestered.[71] The Institution of Professionals, Managers and Specialists (IPMS) suggests that there are areas of work related to climate change which are at present insufficiently researched and funded by government. They cite, as an example of this, the impact of climate change on the transmission of disease among farm animals and pets by insects.[72] We recommend that the Government reconsider the adequacy of the current research programme on the biological effects of climate change, and its funding, and ensure that it is properly integrated with other climate change research.

26. The Minister was confident that the UK "had one of the most effective research programmes on climate change anywhere in the world".[73] We share this confidence, though we believe it could be more effective still. We are not convinced that the UK's national research programme on climate change is sufficiently coherent overall or that it has the required breadth in all areas. The research programme must do more than meet policymakers' current needs for information: it must try to anticipate the advice required in future years.

7 The Reports on the three earlier case studies were: First Report, Session 1998-99, Scientific Advisory System: Genetically Modified Foods, HC 286; Third Report, Session 1998-89, Scientific Advisory System: Mobile Phones and Health, HC 489; Third Report, Session 1999-2000, Scientific Advisory System: Diabetes and Driving Licences, HC 206. Back

8 Press release, No. 1 of Session 1999-2000, 22 November 1999. Back

9 See Fifth Report of the Environment, Transport and Regional Affairs Committee, Session 1999-2000, UK Climate Change Programme, HC194; Fourth Report of the Environmental Audit Committee, Session 1997-98, Climate Change: UK Emission Reduction Targets and Audit Arrangements, HC 899; Second Report of the Environmental Audit Committee, Session 1998-99, Climate Change: Government Response and Follow-up, HC 88. Back

10 See Third Report of the Science and Technology Committee, Session 1996-97, The Natural Environment Research Council and Research into Climate Change, HC 81; and Government Response (Second Special Report, Session 1997-98, HC 306). Back

11 Evidence, p 74, paragraph 3.1. IPCC's Third Assessment Report suggests 0.6 ± 0.2º C. Back

12 Evidence, p 1, paragraph 1. Back

13 IPCC Second Assessment Report, Climate Change 1995. See Evidence, p 39, paragraph 24. Back

14 It was agreed that the industrialised countries would reduce their total greenhouse gas emissions by 5.2% from 1990 levels by the period 2008-2012. Back

15 COP1 met in Berlin in March 1995. COP2 met in Geneva in July 1996. COP4 met in Buenos Aires in November 1998; COP5 in Bonn in October 1999. For details, see www.unfccc.de . Back

16 See www.ipcc.ch . Back

17 Evidence, p 37, paragraph 9. Back

18 For detail of IPCC's working practice, see Evidence, pp 3-7. Back