Originally published by our Content Partner: Intergovernmental Panel on Climate Change (other articles)

Foreword

The Intergovernmental Panel on Climate Change (IPCC) was established by the World Meteorological Organization and the United Nations Environment Programme in 1988 with the mandate to provide the world community with the most up-todate and comprehensive scientific, technical and socio-economic information about climate change. The IPCC multivolume assessments have since then played a major role in motivating governments to adopt and implement policies in responding to climate change, including the United Nations Framework Convention on Climate Change and the Kyoto Protocol.  The “Climate Change 2007” IPCC Fourth Assessment Report could not be timelier for the world’s policy makers to help them respond to the challenge of climate change.

“Climate Change 2007: Impacts, Adaptation and Vulnerability”, is the second volume of the IPCC Fourth Assessment Report. After confirming in the first volume on “The Physical Science Basis” that climate change is occurring now, mostly as a result of human activities, this volume illustrates the impacts of global warming already under way and the potential for adaptation to reduce the vulnerability to, and risks of climate change.

Drawing on over 29,000 data series, the current report provides a much broader set of evidence of observed impacts coming from the large number of field studies developed over recent years. The analysis of current and projected impacts is then carried out sector by sector in dedicated chapters. The report pays great attention to regional impacts and adaptation strategies, identifying the most vulnerable areas. A final section provides an overview of the inter-relationship between adaptation and mitigation in the context of sustainable development.

The “Impacts, Adaptation and Vulnerability” report was made possible by the commitment and voluntary labour of a large number of leading scientists. We would like to express our gratitude to all Coordinating Lead Authors, Lead Authors, Contributing Authors, Review Editors and Reviewers. We would also like to thank the staff of the Working Group II Technical Support Unit and the IPCC Secretariat for their dedication in organising the production of another successful IPCC report. Furthermore, we would like to express our thanks to Dr Rajendra K. Pachauri, Chairman of the IPCC, for his patient and constant guidance to the process, and to Drs Osvaldo Canziani and Martin Parry, Co-Chairs of Working Group II, for their skillful leadership.

We also wish to acknowledge and thank those governments and institutions that contributed to the IPCC Trust Fund and supported the participation of their resident scientists in the IPCC process. We would like to mention in particular the Government of the United Kingdom, which funded the Technical Support Unit; the European Commission and the Belgian Government, which hosted the plenary session for the approval of the report; and the Governments of Australia, Austria, Mexico and South Africa, which hosted the drafting sessions to prepare the report.

Preface

This volumes comprises the Working Group II contribution to the IPCC Fourth Assessment (AR4) and contains a Summary for Policymakers, a Technical Summary, the chapters of the Assessment and various annexes. The scope, content and procedures followed are described in the Introduction which follows.

Acknowledgements

This Report is the product of the work of many scientists who acted as Authors, Reviewers or Editors (details are given in the Introduction, Section E). We would like to express our sincere thanks to them for their contribution, and to their institutions for supporting their participation.

We thank the members of the Working Group II Bureau (Edmundo de Alba Alcarez, Abdelkader Allali, Lucka Kajfež- Bogataj, Geoff Love, John Stone and Jean-Pascal van Ypersele), for carrying out their duties with diligence and commitment.

Costs of the Technical Support Unit (TSU) and of Dr Parry were covered by the UK Department for the Environment, Food and Rural Affairs (Defra). The TSU was based in the Met Office Hadley Centre in the UK. We thank David Warrilow (Defra), Dave Griggs and John Mitchell (Met Office) for their support through these agencies.

Four meetings of Authors were held during the preparation of the Report, and the governments of Austria, Australia, Mexico and South Africa, through their Focal Points, kindly agreed to act as hosts. The Approval Session of the Working Group II contribution to the Fourth Assessment was held in Brussels at the generous invitations of the Government of Belgium, through Martine Vanderstraeten, and the European Community, through Lars Mueller. We thank all these governments, institutions and individuals for their hospitality and hard work on behalf of the Working Group II process.

We thank the IPCC Secretary, Renate Christ, and the Secretariat staff Jian Liu, Rudie Bourgeois, Annie Courtin, Joelle Fernandez and Carola Saibante for their efficient and courteous attention to Working Group II needs; and Marc Peeters, WMO Conference Officer, for his work on the organisation of the Brussels Approval Meeting.

Thanks go to ProClim (Forum for Climate and Global Change) and Marilyn Anderson for producing the index to this Report.

Last, but by no means least, we acknowledge the exceptional commitment of the members of the Technical Support Unit throughout the preparation of the Report: Jean Palutikof, Paul van der Linden, Clair Hanson, Norah Pritchard, Chris Sear, Carla Encinas and Kim Mack.

Introduction to the Working Group II Fourth Assessment Report

A. The Intergovernmental Panel on Climate Change

The Intergovernmental Panel on Climate Change (IPCC) was established by the World Meteorological Organization and the United Nations Environment Programme in 1988, in response to the widespread recognition that human-influenced emissions of greenhouse gases have the potential to alter the climate system. Its role is to provide an assessment of the understanding of all aspects of climate change.

At its first session, the IPCC was organised into three Working Groups. The current remits of the three Working Groups are for Working Group I to examine the scientific aspects of the climate
system and climate change; Working Group II to address vulnerabilities to, impacts of and adaptations to climate change; and Working Group III to explore the options for mitigation of climate change. The three previous assessment reports were produced in 1990, 1996 and 2001.

B. The Working Group II Fourth Assessment

The decision to produce a Fourth Assessment Report was taken by the 19th Session of the IPCC at Geneva in April 2002. The report was to be more focussed and shorter than before. The Working Group II contribution was to be finalised in mid-2007.

The IPCC Fourth Assessment is intended to be a balanced assessment of current knowledge. Its emphasis is on new knowledge acquired since the IPCC Third Assessment (2001). This required a survey of all published literature, including non-English language and ‘grey’ literature such as government and NGO reports.

Two meetings were held in 2003 to scope the Fourth Assessment, from which emerged the outline for the Working Group II Assessment submitted to IPCC Plenary 21 in November 2003 for approval and subsequent acceptance.

The Report has twenty chapters which together provide a comprehensive assessment of the climate change literature. These are shown in Table I.1. The opening chapter is on observed changes, and addresses the question of whether observed changes in the natural and managed environment are associated with anthropogenic climate change. Chapter 2 deals with the methods
available for impacts analysis, and with the scenarios of future climate change which underpin these analyses. These are followed by the core chapters, which assess the literature on present day and future climate change impacts on systems, sectors and regions, vulnerabilities to these impacts, and strategies for adaptation. Chapters 17 and 18 consider possible responses through adaptation and the synergies with mitigation. The two final chapters look at key vulnerabilities, and the interrelationships between climate change and sustainability.

Chapters 9 to 16 of the Working Group II Fourth Assessment consider regional climate change impacts. The definitions of these regions are shown in Table I.2.

Table I.2. Countries by region (see Chapters 9 to 16) for the Working Group II Fourth Assessment.

C. Cross-chapter case studies

Early in the writing of the Working Group II contribution to the Fourth Assessment, there emerged themes of environmental importance and widespread interest which are dealt with from different perspectives by several chapters. These themes have been gathered together into ‘cross-chapter case studies’, which appear in their entirety at the end of the volume and are included in the CD-ROM which accompanies this volume. A ‘roadmap’ in Table I.3 shows where the cross-chapter case study material appears in the individual chapters.

The four cross-chapter case studies are:

1. The impact of the European 2003 heatwave
2. Impacts of climate change on coral reefs
3. Megadeltas: their vulnerabilities to climate change
4. Indigenous knowledge for adaptation to climate change

D. Regional and subject database of references

This Assessment is based on the review of a very large amount of literature for all parts of the world and for many subjects. For those interested in accessing this literature for a given region or
subject, a regional and subject database of references is provided on the CD-ROM which accompanies this volume. The database contains in full all the references in this volume and can be viewed by region and subject.

E. Procedures followed in this Assessment by the authors, reviewers and participating governments

In total, the Working Group II Fourth Assessment involved 48 Coordinating Lead Authors (CLAs), 125 Lead Authors (LAs), and 45 Review Editors (REs), drawn from 70 countries. In addition, there were 183 Contributing Authors and 910 Expert Reviewers.

Each chapter in the Working Group II Fourth Assessment had a writing team of two to four CLAs and six to nine LAs. Led by the CLAs, it was the responsibility of this writing team to produce the drafts and finished version of the chapter. Where necessary, they could recruit Contributing Authors to assist in their task. Three drafts of each chapter were written prior to the production of the final version. Drafts were reviewed in two separate lines of review, by experts and by governments. It was the role of the REs (two to three per chapter) to ensure that the review comments were properly addressed by the authors.

The authors and REs were selected by the Working Group II Bureau from the lists of experts nominated by governments. Due regard was paid to the need to balance the writing team with proper representation from developing and developed countries, and Economies in Transition. In the review by experts, chapters were sent out to experts, including all those nominated by governments but not yet included in the assessment, together with scientists and researchers identified by the Working Group II Co-Chairs and Vice-Chairs from their knowledge of the literature and the global research community.

Table I.3. Cross-chapter Case Studies: location in text.

F. Communication of uncertainty in the Working Group II Fourth Assessment

A set of terms to describe uncertainties in current knowledge is common to all parts of the IPCC Fourth Assessment, based on the Guidance Notes for Lead Authors of the IPCC Fourth Assessment Report on Addressing Uncertainties1, produced by the IPCC in July 2005.

Description of confidence

On the basis of a comprehensive reading of the literature and their expert judgement, authors have assigned a confidence level to the major statements in the Report on the basis of their assessment of current knowledge, as follows:

Terminology                            Degree of confidence in being correct
Very high confidence            At least 9 out of 10 chance of being correct
High confidence                     About 8 out of 10 chance
Medium confidence                About 5 out of 10 chance
Low confidence                     About 2 out of 10 chance
Very low confidence             Less than a 1 out of 10 chance

Description of likelihood

Likelihood refers to a probabilistic assessment of some well-defined outcome having occurred or occurring in the future, and may be based on quantitative analysis or an elicitation of expert views. In the Report, when authors evaluate the likelihood of certain outcomes, the associated meanings are:

Terminology                           Likelihood of the occurrence/ outcome
Virtually certain                      >99% probability of occurrence
Very likely                              90 to 99% probability
Likely                                     66 to 90% probability
About as likely as not            33 to 66% probability
Unlikely                                 10 to 33% probability
Very unlikely                          1 to 10% probability
Exceptionally unlikely             <1% probability

G. Definitions of key terms

Climate change in IPCC usage refers to any change in climate over time, whether due to natural variability or as a result of human activity. This usage differs from that in the Framework
Convention on Climate Change, where climate change refers to a change of climate that is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods.

Adaptation is the adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities.

Vulnerability is the degree to which a system is susceptible to, and unable to cope with, adverse effects of climate change, including climate variability and extremes. Vulnerability is a function of the character, magnitude, and rate of climate change and variation to which a system is exposed, the sensitivity and adaptive capacity of that system.