The IPCC Assessment Process
The Intergovernmental Panel on Climate Change (IPCC) has the responsibility for conducting assessments of climate change and its consequences. To date, the IPCC has issued comprehensive assessments in 1990, 1996 and in 2001. Its most recent report, the Third Assessment Report (TAR), is comprised of four sections. Three of these sections are working groups; the fourth is a Synthesis Report. Working Group I (WG I) focused on climate change science, Working Group II focused on potential impacts and adaptation options, while Working Group III focused on mitigation options and related socioeconomic issues.
Hundreds of scientific researchers, policy experts, and risk analysts from all over the world have directly contributed to the assessment -- the most comprehensive analysis of climate change written to date. The scientific credibility of the TAR -- and the process by which it is reviewed by the international scientific community and then considered and accepted by the government members of the IPCC -- means that the report will likely be influential in the policy arena.
AN OVERVIEW OF THE IPCC
The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 under the auspices of the United Nations Environment Programme and the World Meteorological Organization for the purpose of assessing "the scientific, technical and socioeconomic information relevant for the understanding of the risk of human-induced climate change. It does not carry out new research nor does it monitor climate-related data. It bases its assessment mainly on published and peer reviewed scientific technical literature" [1]. The IPCC was formed specifically to inform international policy and negotiations on climate issues.
Historically, the IPCC has been organized into three working groups, a variety of task forces or special committees, and a small secretariat in Geneva. Scientists from 120 nations participate in the preparation of the IPCC reports. The topical assignments to the working groups have evolved somewhat over time. For the Third Assessment Report, Working Group I was charged with assessing the scientific aspects of the climate system and climate change. Working Group II was charged with addressing vulnerability of human and natural systems to climate change (i.e., the negative and positive consequences of climate change), and options for adapting to them. Working Group III was charged with assessing options for limiting greenhouse gas (GHG) emissions and other types of mitigation, as well as economic issues. A separate Task Force oversaw a program to compile national greenhouse gas inventories. Each of these four bodies had two co-chairs -- one from a developed and one from a developing country.
Each working group published an in-depth technical report, a Technical Summary, and a short Summary for Policymakers (SPM). In addition, the major findings and conclusions from all three reports provided the basis for preparing a Synthesis Report. Each Working Group held a plenary session to resolve final questions raised during the review phases and reached final approval of the Summaries for Policymakers. The entire IPCC Plenary met in April 2001 to approve the contributions of the three Working Groups, and then in September 2001 to approve the Synthesis report. The resulting documents were made public at the conclusion of each plenary.
Each Working Group was co-chaired by a leading scientist from a developed and developing country. An additional set of governmental representatives (frequently trained scientists) nominated by countries made up the Bureau for each Working Group. Together, the two co-authors and the bureau members functioned as an executive committee for the Working Group. The team of scientists actually drafting individual chapters was sometimes referred to as the "scientific core." Coordinating the efforts of each working group was a small Technical Support Unit that provided technical and administrative support to the bureau and the wider set of scientific authors who were invited to participate in the process.
It is important to note that although the IPCC is organized within a political institutional framework, it is fundamentally a scientific body—made up and led by leading scientists from around the world. In order to remain true to its scientific mandate and to maintain scientific objectivity, the IPCC is careful to avoid making policy recommendations or shaping research programs. Because the assessments of the IPCC are the most comprehensive and balanced evaluations of the climate change issue, however, its work is probably the single most important foundation on which climate policy is built [2].
THE FIRST TWO ASSESSMENTS
The First Assessment Report (FAR) of the IPCC (1990), as well as a supplemental report prepared in 1992, supported establishment of the UN Framework Convention on Climate Change (UNFCCC) at the Rio Earth Summit in 1992. The UNFCCC serves as the foundation of international, political efforts to combat global warming. The IPCC's reports were also influential at the first Conference of the Parties to the Climate Convention, held in Berlin, Germany in 1995. Policymakers produced the so-called Berlin Mandate, setting out the terms for a negotiation process leading to binding commitments by industrial countries to reduce their heat-trapping gas emissions after the year 2000.
The significantly strengthened Second Assessment Report (SAR - 1996) -- and additional special materials on the implications of various potential emissions limitations and on regional consequences -- provided key input to the negotiations that led to the adoption of the Kyoto Protocol to the UNFCCC in 1997. The Kyoto Protocol is an international agreement that establishes binding targets for reduction of greenhouse gases emitted by developed countries. Since the SAR, a number of technical papers and special reports have been prepared, including ones on aircraft, land use, technology, and emissions scenarios.
THE THIRD ASSESSMENT REPORT
The Third Assessment Report (TAR) is the latest comprehensive assessment report to be produced by the IPCC. The different parts of the TAR were released in stages between January and April 2001. The dates and locations for the plenaries were as follows:
- WG I Plenary: January 17-20 -- Shanghai, China
- WG II Plenary: February 13-16 -- Geneva, Switzerland
- WG III Plenary: February 28-March 3 -- Accra, Ghana
- Full IPCC Plenary: April 4-6 -- Nairobi, Kenya
- Full IPCC Plenary: September 24-29 -- London, UK
AUTHORS, CONTRIBUTORS, AND REVIEWERS
The Technical Support Units, Co-Chairs, and Bureaus of each Working Group together assemble a list of proposed authors for an assessment report, but the final selection of lead authors is done by the full plenary of each Working Group. International organizations, including non-governmental organizations, are invited to nominate potential authors. Likewise, governments can nominate scientists for the list of potential authors. A government nomination does not imply that governments endorse the scientist's views, or that a scientist has to represent his/her government's view. At most, it means that governments are willing to financially support an expert. However, many scientists receive no financial support at all; others receive only reimbursement of travel expenses. Developing country experts who receive no financial support from their home countries are supported through the IPCC trust fund.
From these nominations, the Working Group plenaries confirm 5 to 10 lead and coordinating lead authors, as well as two review editors, for each chapter of the report. Appointed scientists -- who typically are widely recognized experts – come from academia, research facilities, industry, government, and non-government organizations. Authors are chosen to represent a broad range of expertise and opinion, and each chapter must have at least one lead author from a developing country. Lead authors from the United States for TAR Working Group I, include, among others: John Christy, Tom Karl, Richard Lindzen, Linda Mearns, Jerry Meehl, Susan Solomon, and Kevin Trenberth; the other WGs have similarly highly qualified individuals. [A complete list of the lead authors is available at the IPCC web site.]
The lead authors and coordinating lead authors prepare a first draft over a period of several months, reviewing and synthesizing the vast amount of primary published and peer-reviewed scientific literature. During this time, chapter lead authors consult with expert scientists in the field, inviting those with needed expertise to serve as contributing authors. The chapter teams hold several author meetings to clarify the issues and to reach agreement on scope, balance, and conclusions of the report. The role of contributing authors is to co-author specific sections or to contribute specific data or to represent particular viewpoints. Lead authors typically solicit these contributions, but scientists are also encouraged, both individually and by their countries, to become contributing authors by submitting material directly to the chairs of the relevant working group.
The resulting first draft of a chapter then undergoes two rounds of review and revision (described more fully below) before being finalized. Many authors will attest that these are among the most extensive review processes that are carried out for any scientific document. The revised chapters are next combined into a technical report by the Technical Support Units and then circulated to governments and accredited NGOs before being considered and "accepted" at the Working Group plenaries. Being "accepted" means that governmental representatives to the IPCC agree that the documents present an objective, comprehensive, and balanced scientific review of the subject matter. This acceptance process does not provide for or permit a line-by-line review and editing of these book-length reports by the government representatives; in the end, these chapters are fully the responsibility of their authors and are not dictated by governments.
The much shorter Summary for Policymakers of each working group goes through a concurrent but separate writing and review process. Drafted by the lead authors, and reviewed in two stages by technical experts, the final draft is "approved" in the working group plenary after extensive discussion and line-by-line review and revision by the governmental representatives. (See footnote at end of update describing in more detail the work of the plenaries.)
In this process, governmental representatives may certainly try to influence the wording in ways that support their negotiating positions. However, the overriding check in this system -- and the key challenge and goal -- is that the SPM must adequately and appropriately represent the underlying technical report that has been prepared by the scientific community. To ensure that this occurs, lead and several contributing authors are typically on hand at the plenaries to render interpretations, suggest clarifications, and ensure scientific integrity. The entire process ensures that there are many opportunities for differing views to be expressed and included, if there is empirical evidence or plausible reasons to support them.
THE PEER-REVIEW PROCESS
The IPCC and the TAR derive their credibility principally from a very extensive, iterative peer-review process. According to participants, this process is far more exhaustive (and exhausting!) than the peer review process associated with scientific journals. This is so because of the number of reviewers, the breadth of their disciplinary backgrounds and scientific perspectives, and the inclusion of "review editors" in the process who certify that all comments are fairly considered and appropriately acted upon by the authors. (For an inspiring example of this, see [3].)
With the goal of being as inclusive and open as possible, assurance of a balanced review really begins with the choice of lead authors. By intentionally including authors representing the range of expert points of view, many areas of disagreement are worked out in discussions among the authors, and so resolved before the document is sent out for review. Once a first draft has been written, it is sent to "expert reviewers" for technical review. The list of expert reviewers is long -- more than 1,000 for the entire TAR -- and includes scientists and NGO experts with a wide range of perspectives. Lead authors are required to consider all comments and to incorporate those with scientific merit -- a process overseen by review editors (two per chapter). Copies of all review comments are archived together with authors' responses/action on them, and are available upon request.
If areas of major differences emerge, lead authors are encouraged to organize a meeting with contributing authors and reviewers to discuss and resolve the differences. The goal here is not to arrive at a "watered-down" compromise that conceals scientific uncertainties or real differences in expert opinion, but rather to write a report of the highest scientific integrity that reflects the state of knowledge fairly and adequately.
The revised draft is then sent back to the original expert reviewers and to government representatives for the so-called "government review" stage. Each government is entitled to organize any type of review process it deems appropriate. The US government, for example, seeks comments from agencies, scientific experts, and the general public (through a Federal Register notice) as the starting point for preparing its unified comments. [See Relevant Websites, below.] Again, lead authors prepare revisions based on review comments that are scientifically valid, and authors are encouraged to work out major remaining differences by communicating with reviewers and other experts. The resulting document is then submitted to the plenary for consideration and acceptance.
FAIR REPRESENTATION OF A RANGE OF EXPERT OPINIONS
One critical strategy in ensuring scientific credibility and political legitimacy of IPCC reports is to strive for a fair representation of the range of scientific opinion on climate change matters. To this end, the IPCC has provided several channels for input from experts along the entire spectrum of opinion on climate change, including climate change skeptics.
First, accredited non-governmental organizations, from all sides of the issue, have observer status at the opening plenary and some other sessions over the course of the assessment cycle. The Climate Coalition and Climate Council, for example, are accredited organizations participating in the review process. Second, some chapter lead authors are well known contrarians of the majority view -- such as Richard Lindzen, an atmospheric scientist from MIT and John Christy from the University of Alabama-Huntsville. Skeptics can also (and do) become contributing authors by submitting material to lead authors. Finally, several well known, outspoken contrarians, such as Fred Singer and Vincent Gray, contribute directly to the process as reviewers. In addition, yet less formally, some contrarians are in advisory roles with some governments, directly advising the government representatives at different points in the process, including during the discussion and approval of the final SPMs. (See [3].)
The IPCC also seeks to involve experts from outside the traditional set of research institutions, and accordingly, climate change experts from industry and environmental organizations have been involved in the IPCC process. Those from industry, for example, have included Brian Flannery and Haroon Kheshgi from Exxon-Mobil, and Chuck Hakkarinen and Rich Richels from Electric Power Research Institute. Those from environmental organizations have included, among others, climate expert Michael Oppenheimer from Environmental Defense as a lead author, and experts from NGOs such as the Union of Concerned Scientists, the Natural Resources Defense Council, and others from all over the world as contributing authors and reviewers.
Climate contrarians frequently claim that the IPCC produces politically motivated reports that show only one side (i.e., not theirs) of the issues. Given the many stages at which experts from across the political and scientific spectrum are included in the process, this is a very difficult position to defend [4]. Furthermore, according to the IPCC principles, lead authors are "required to record views in the text which are scientifically or technically valid, even if they cannot be reconciled with a consensus view" [5]. Vincent Gray, an outspoken skeptic from New Zealand, submitted 97 pages of comments on the first draft of the TAR and has written that, "[I]n many cases I have been agreeably surprised to find that [my comments] were accepted" [6]. The bottom line -- and guiding principle of the IPCC -- is that if a point is scientifically supportable, no matter its source, it will be included in the TAR.
CONSENSUS BUILDING WITHIN THE IPCC
The word "consensus" is often invoked, and sometimes questioned, when speaking of IPCC reports such as the TAR. In fact, there are two arenas in which consensus needs to be reached in the production of IPCC assessments. One arena is the plenary, in which unanimity is sought among governmental representatives to the IPCC. It is particularly impressive that full consensus has been achieved in the final "sign-off" of all documents and SPMs. Such consensus is not required—countries are allowed to formally register their dissents; in all cases to date, however, agreement has been reached.
The other arena where consensus is sought is among the scientists writing each chapter of the report. In this case, consensus does not mean that everyone agrees with every aspect of the report -- a clearly unrealistic aim. Perhaps more important, it is well understood that science is not something to be decided by voting, but rather that logical reasoning is the goal. The core, then, of this scientific consensus is that the WG authors agree that a fair representation of the scientific debate has been achieved. Points of dispute in the science of climate change are usually resolved either by developing appropriate intervals of uncertainty around certain projections or by crafting language that reflects the different viewpoints of experts within the scientific community and the reasons that the differences exist [4].
The level of acceptance of the final assessment within this extensive community of scientists is, therefore, quite remarkable. It is fair to say that the TAR represents a highly balanced, carefully explained view of the state of climate change science. The final document, even with its inevitably hedged language and qualified conclusions, is thus a very powerful one.
THE ROLE OF GOVERNMENTS
Although the TAR is a scientific report, it is written in order to inform international political negotiations on climate issues. Therefore, governments -- as the stakeholders in these negotiations -- play an essential role. By proposing experts as authors and contributors, having a voice in the review process, and reaching consensus on the reports' major findings, governmental experts are active participants in the assessment process. Especially in the SPMs, the breadth of national viewpoints can result in language that is sometimes weaker than it otherwise might be.
But it also means that governments cannot easily criticize or dismiss a report they helped shape and signed off on during subsequent political negotiations. As Sir John Houghton, Co-Chair of Working Group I, once put it: "any move to reduce political involvement in the IPCC would weaken the panel and deprive it of its political clout.… If governments were not involved, then the documents would be treated like any old scientific report. They would end up on the shelf or in the waste bin" [7]. It is important, however, to reiterate a most basic point: although governments are involved in the process and support it financially, ultimately science predominates. The chapters that underpin all the documents are written by and are under the control of the lead authors (scientists), and scientists ensure that all documents are both consistent with these foundation chapters and scientifically credible.
CONCLUSION
Working Group I's TAR Summary for Policymakers concluded that temperature increases over the 21st century could be significantly larger than previously thought, and that the evidence for human influence on climate change is stronger than ever. The inclusive process by which IPCC assessments are developed and accepted by its members results in reports of exceptional scientific credibility. As such, the TAR has the potential to be extremely influential in the formation of policy over the next several years, as have the previous two IPCC reports.
REFERENCES
- Cited from IPCC Web Page
- Agrawala, S., Structural and process history of the Intergovernmental Panel on Climate Change, Climatic Change, 39, 621-642, 1998.
- Edwards, Paul and Steve Schneider, Climate Change: Broad Consensus or "Scientific Cleansing"?, Ecofables/Ecoscience, 1, 3-9, 1997.
- Masood, E., Head of Climate Group Rejects Claims of Political Influence, Nature, 381, 455, 1996.
- Cited from IPCC Principles and Procedures
- Vincent Gray's comments on the first draft of the TAR
- Alfsen, K, and Skodvin, T., The Intergovernmental Panel on Climate Change (IPCC) and scientific consensus, Policy Note 1998: 3, Center for International Climate and Environmental Research, University of Oslo, Norway, 1998.
