The Intergovernmental Panel on Climate Change (IPCC) is a scientific intergovernmental body tasked with evaluating the risk of climate change caused by human activity. The panel was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), two organizations of the United Nations. The IPCC shared the 2007 Nobel Peace Prize with former Vice President of the United States Al Gore.
The IPCC does not carry out its own original research, nor does it do the work of monitoring climate or related phenomena itself. A main activity of the IPCC is publishing special reports on topics relevant to the implementation of the UN Framework Convention on Climate Change (UNFCCC), an international treaty that acknowledges the possibility of harmful climate change. Implementation of the UNFCCC led eventually to the Kyoto Protocol. The IPCC bases its assessment mainly on peer reviewed and published scientific literature. The IPCC is only open to member states of the WMO and UNEP. IPCC reports are widely cited in almost any debate related to climate change. National and international responses to climate change generally regard the UN climate panel as authoritative.
The summary reports (i.e. Summary for Policymakers), which draw the most media attention, include review by participating governments in addition to scientific review.
The principles of the IPCC operation are assigned by the relevant WMO Executive Council and UNEP Governing Council resolutions and decisions as well as on actions in support of the UN Framework Convention on Climate Change process.
The stated aims of the IPCC are to assess scientific information relevant to:
|UNFCCC | WMO | UNEP|
The IPCC published its first assessment report in 1990, a supplementary report in 1992, a second assessment report (SAR) in 1995, and a third assessment report (TAR) in 2001. A fourth assessment report (AR4) was released in 2007. Each assessment report is in three volumes, corresponding to Working Groups I, II and III. Unqualified, "the IPCC report" is often used to mean the Working Group I report, which covers the basic science of climate change.
The IPCC first assessment report was completed in 1990, and served as the basis of the United Nations Framework Convention on Climate Change (UNFCCC).
The executive summary of the WG I Summary for Policymakers report says they are certain that emissions resulting from human activities are substantially increasing the atmospheric concentrations of the greenhouse gases, resulting on average in an additional warming of the Earth's surface. They calculate with confidence that CO2 has been responsible for over half the enhanced greenhouse effect. They predict that under a "business as usual" (BAU) scenario, global mean temperature will increase by about 0.3 oC per decade during the [21st] century. They judge that global mean surface air temperature has increased by 0.3 to 0.6 oC over the last 100 years, broadly consistent with prediction of climate models, but also of the same magnitude as natural climate variability. The unequivocal detection of the enhanced greenhouse effect is not likely for a decade or more.
The 1992 supplementary report was an update, requested in the context of the negotiations on the Framework Convention on Climate Change at the Earth Summit (United Nations Conference on Environment and Development) in Rio de Janeiro in 1992.
The major conclusion was that research since 1990 did "not affect our fundamental understanding of the science of the greenhouse effect and either confirm or do not justify alteration of the major conclusions of the first IPCC scientific assessment". It noted that transient (time-dependent) simulations, which had been very preliminary in the FAR, were now improved, but did not include aerosol or ozone changes.
Climate Change 1995, the IPCC Second Assessment Report (SAR), was finished in 1996. It is split into four parts:
Each of the last three parts was completed by a separate working group, and each has a Summary for Policymakers (SPM) that represents a consensus of national representatives. The SPM of the WG I report contains headings:
Keith Shine, one of IPCC's lead authors, discussing the Policymakers' Summary, said: "We produce a draft, and then the policymakers go through it line by line and change the way it is presented.... It's peculiar that they have the final say in what goes into a scientists' report". It is not clear, in this case, whether Shine was complaining that the report had been changed to be more skeptical, or less, or something else entirely.
Solid-state physicist Frederick Seitz, president emeritus of Rockefeller University, past president of the National Academy of Sciences, and former health consultant for R. J. Reynolds Tobacco Company publicly denounced the IPCC report, writing "I have never witnessed a more disturbing corruption of the peer-review process than the events that led to this IPCC report". He opposed it in the Leipzig Declaration of S. Fred Singer's Science and Environmental Policy Project.
In turn, Seitz's comments were vigorously opposed by the presidents of the American Meteorological Society and University Corporation for Atmospheric Research, who wrote about a "systematic effort by some individuals to undermine and discredit the scientific process that has led many scientists working on understanding climate to conclude that there is a very real possibility that humans are modifying Earth's climate on a global scale. Rather than carrying out a legitimate scientific debate... they are waging in the public media a vocal campaign against scientific results with which they disagree".
Santer's position was supported by fellow IPCC authors and senior figures of the American Meteorological Society and University Corporation for Atmospheric Research. In 1997, Paul Edwards and IPCC author Stephen Schneider published a paper rebutting criticisms of the IPCC report.
The Second Assessment Report was controversial in its treatment of the economic value of human life. In environmental economics, it is customary to value the health impacts of climate change on the basis of willingness to pay for risk reduction. An advantage of this method is that health risks of climate change are treated like any other health risk. Some have commented on the difficultly of calculating the costs of climate change impacts such as human mortality. For example, in calculations based on risk reduction, the value of a statistical life is assessed to be much higher in rich countries than in poor countries.
This information was presented in the full Second Assessment Report, however, dispute arose over the Report's Summary for Policymakers. The Summary for Policymakers (SPM) is prepared with the input of government delegates and IPCC experts. Governments were unhappy with the cost-benefit valuation of human life, and this was implied in the SPM. David Pearce, the IPCC convening lead author who oversaw the relevant chapter of the Report, officially dissented on this summary, commenting that:
The relevant chapter [of the Report] values of statistical life based on actual studies in different countries. Whether the values used remain as in Chapter 6 or whether a common global average is used makes no difference to the results. What the authors of Chapter 6 did not accept, and still do not accept, was the call from a few [government] delegates for a common valuation based on the highest number for willingness to pay.
Many of us think that the governments were basically right. The metric [used by Pearce] makes sense for determining how a given government might make tradeoffs between its own internal projects. But the same logic fails when the issue is one of damage inflicted by some countries on others: why should the deaths inflicted by the big emitters — principally the industrialised countries — be valued differently according to the wealth of the victims' countries?
The Third Assessment Report (TAR) consists of four reports, three of them from its working groups:
The "headlines" from the Summary for Policymakers in The Scientific Basis were:
The TAR estimate for the climate sensitivity is 1.5 to 4.5 °C; and the average surface temperature is projected to increase by 1.4 to 5.8 Celsius degrees over the period 1990 to 2100, and the sea level is projected to rise by 0.1 to 0.9 meters over the same period. The wide range in predictions is based on scenarios that assume different levels of future CO2 emissions. Each scenario then has a range of possible outcomes associated with it. The most optimistic outcome assumes an aggressive campaign to reduce CO2 emissions; the most pessimistic is a "business as usual" scenario. Other scenarios fall in between.
IPCC uses the best available predictions and their reports are under strong scientific scrutiny. The IPCC concedes that there is a need for better models and better scientific understanding of some climate phenomena, as well as the uncertainties involved. Critics assert that the data is insufficient to determine the real importance of greenhouse gases in climate change. Sensitivity of climate to greenhouse gases may be overestimated or underestimated because of flaws in the models and because the importance of some external factors may be misestimated. The predictions are based on scenarios, and the IPCC did not assign any probability to the 35 scenarios used.
Castles and Henderson asserted that the IPCC's use of market exchange rates in the Special Report on Emissions Scenarios to convert GDP measures into a common currency is inappropriate, and that, for most countries a Purchasing Power Parity conversion would yield higher estimates of income. It follows that the rate of growth implied by an assumption of income convergence is higher if exchange rate conversions are used. They imply that this is likely to produce biased projections of emissions. Nebojsa Nakicenovic et al. claim that this is incorrect because, provided an internally consistent procedure is used, projections of emissions are unaffected by the choice of index number used to measure GDP. See the discussion under Special Report on Emissions Scenarios.
MIT professor Richard Lindzen, one of the lead authors of the IPCC Working Group I Report, has criticised the IPCC Summary for Policymakers document before the U.S. Senate Committee on Commerce, Science and Transportation. Taking Chapter 7, Physical Processes, on which he worked, he said that it "found numerous problems with model treatments – including those of clouds and water vapor", the chapter was summarized in the single sentence "Understanding of climate processes and their incorporation in climate models have improved, including water vapor, sea-ice dynamics, and ocean heat transport."
Sir John Houghton, former Chair of the IPCC Working Group I Report, has commented on Lindzen's criticisms of the IPCC:, saying that Lindzen, having previously expressed satisfaction with the report, had "gone on to express his view that the conclusions of the Policymakers Summary did not faithfully represent the chapters. But he has never provided any supporting evidence for that statement." He emphasized that the Policymaker's Summaries were "agreed unanimously at intergovernmental meetings involving over 200 government delegates from around 100 countries...after several days of scientific debate (only scientific arguments not political ones are allowed) the main purpose of which is to challenge the scientific chapter authors regarding the accuracy, clarity and relevance of the summary and most especially its consistency with the underlying chapters."
|The four SRES scenario families of the Fourth Assessment Report vs. associated changes in global-mean temperature until 2100|
|more economic focus||more environmental focus|
rapid economic growth
1.4 - 6.4 °C
global environmental sustainability
1.1 - 2.9 °C
2.0 - 5.4 °C
local environmental sustainability
1.4 - 3.8 °C
The Fourth Assessment Report (AR4) was completed in early 2007. Like previous assessment reports, it consists of four reports, three of them from its working groups.
Working Group I dealt with the "Physical Science Basis of Climate Change." The Working Group I Summary for Policymakers (SPM) was published on February 2, 2007 and revised on February 5, 2007. There was also a February 2, 2007 press release. The full WGI report was published in March. The key conclusions of the SPM were that:
In IPCC statements "most" means greater than 50%, "likely" means at least a 66% likelihood, and "very likely" means at least a 90% likelihood.
The Summary for Policymakers for the Working Group II report was released on April 6, 2007. The Summary for Policymakers for the Working Group III report was released on May 4, 2007. The AR4 Synthesis Report (SYR) was released on November 17, 2007.
The IPCC is currently starting to outline its Fifth Assessment Report (AR5) which will be finalized in 2014. As it has been the case in the past, the outline of the AR5 will be developed through a scoping process which involves climate change experts from all relevant disciplines and users of IPCC reports, in particular representatives from governments. As a first step, experts, governments and organizations involved in the Fourth Assessment Report have been asked to submit comments and observations in writing. These submissions are currently being analysed by members of the Bureau. The scoping meeting of experts to define the outline of the AR5 is scheduled for 13-17 July 2009. The outline was submitted to the 31st Session of the IPCC held in Bali, Indonesia, 26-29 October 2009.
Within IPCC the National Greenhouse Gas Inventory Program (IPCC-NGGIP) develops methods and methodologies to estimate emissions of greenhouse gases. IPCC-NGGIP has been undertaken since 1991 by the IPCC WG I in close collaboration with the Organisation for Economic Co-operation and Development (OECD) and the International Energy Agency (IEA). The objectives of the IPCC-NGGIP are:
The Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories (1996 GLs) provide the methodological basis for the estimation of national greenhouse gas emission inventory. Over time these 1996GLs have been completed with guidance on so-called "Good Practice":
The 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC 2006 GLs) comprises the latest versions of these emission estimation methodologies, including a large number of default emission factors. Although the IPCC has prepared these new version of the guidelines on request of the partires to the UNFCCC, the methods have not been officially accepted yet for use in national greenhouse gas emisiosns reporting under the UNFCCC and the Kyoto Protocol.
The Chair of the IPCC is Rajendra K. Pachauri, elected in May 2002; previously Robert Watson headed the IPCC. The chair is assisted by an elected Bureau including vice-chairs, Working Group co-chairs and a Secretariat (see below).
The IPCC Panel is composed of representatives appointed by governments and organizations. Participation of delegates with appropriate expertise is encouraged. Plenary sessions of the IPCC and IPCC Working Groups are held at the level of government representatives. Non Governmental and Intergovernmental Organizations may be allowed to attend as observers. Sessions of the IPCC Bureau, workshops, expert and lead authors meetings are by invitation only. Attendance at the 2003 meeting included 350 government officials and climate change experts. After the opening ceremonies, closed plenary sessions were held. The meeting report  states there were 322 persons in attendance at Sessions with about seven-eighths of participants being from governmental organizations.
The IPCC has published four comprehensive assessment reports reviewing the latest climate science, as well as a number of special reports on particular topics. These reports are prepared by teams of relevant researchers selected by the Bureau from government nominations. Drafts of these reports are made available for comment in open review processes to which anyone may contribute.
The IPCC does not carry out research nor does it monitor climate related data. The responsibility of the lead authors of IPCC reports is to assess available information about climate change drawn mainly from the peer reviewed and published scientific/technical literature.
There are several major groups:
The IPCC receives funding from UNEP, WMO, and its own Trust Fund for which it solicits contributions from governments.
People from over 130 countries contributed to the IPCC Fourth Assessment Report over the previous 6 years. These people included more than 2500 scientific expert reviewers, more than 800 contributing authors, and more than 450 lead authors.
Of these, the Working Group 1 report (including the summary for policy makers) included contributions by 600 authors from 40 countries, over 620 expert reviewers, a large number of government reviewers, and representatives from 113 governments.
The IPCC concentrates its activities on the tasks allotted to it by the relevant WMO Executive Council and UNEP Governing Council resolutions and decisions as well as on actions in support of the UN Framework Convention on Climate Change process.
The AR4 Synthesis Report (SYR) was finalized in November 2007. Documentation on the scoping meetings for the AR4 are available as are the outlines for the WG I report PDF (11.5 KB) and a provisional author list PDF (108 KB).
While the preparation of the assessment reports is a major IPCC function, it also supports other activities, such as the Data Distribution Centre and the National Greenhouse Gas Inventories Programme, required under the UNFCCC. This involves publishing default emission factors, which are factors used to derive emissions estimates based on the levels of fuel consumption, industrial production and so on.
The IPCC also often answers inquiries from the UNFCCC Subsidiary Body for Scientific and Technological Advice (SBSTA).
The IPCC reports are a compendium of peer reviewed and published science. Each subsequent IPCC report notes areas where the science has improved since the previous report and also notes areas where further research is required.
There are generally three stages in the review process:PDF (55.7 KB)
Review comments are in an open archive for at least five years.
There are several types of endorsement which documents receive:
The Panel is responsible for the IPCC and its endorsement of Reports allows it to ensure they meet IPCC standards. The Panel's approval process has been criticized for changing the product of the experts who create the Reports. On the other hand, not requiring Panel re-endorsement of Reports has also been criticized, after changes required by the approval process were made to Reports.
Each chapter has a number of authors who are responsible for writing and editing the material. A chapter typically has two Coordinating Lead Authors, ten to fifteen Lead Authors, and a somewhat larger number of Contributing Authors. The Coordinating Lead Authors are responsible for assembling the contributions of the other authors, ensuring that they meet stylistic and formatting requirements, and reporting to the Working Group chairs. Lead Authors are responsible for writing sections of chapters. Contributing Authors prepare text, graphs or data for inclusion by the Lead Authors.
Authors for the IPCC reports are chosen from a list of researchers prepared by governments, and participating organisations and the Working Group/Task Force Bureaux, and other experts as appropriate, known through their publications and works (PDF, 4.2.1,2). The composition of the group of Coordinating Lead Authors and Lead Authors for a section or chapter of a Report is intended to reflect the need to aim for a range of views, expertise and geographical representation (ensuring appropriate representation of experts from developing and developed countries and countries with economies in transition).
In December 2007, the IPCC was awarded the Nobel Peace Prize "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change." The award is shared with Former U.S. Vice-President Al Gore for his work on climate change and the documentary An Inconvenient Truth.
A paragraph in the 2007 Working Group II report ("Impacts, Adaptation and Vulnerability"), chapter 10 included a projection that Himalayan glaciers could disappear by 2035
This projection was not included in the final summary for policymakers. The IPCC has since acknowledged that the date is incorrect, while reaffirming that the conclusion in the final summary was robust. They expressed regret for "the poor application of well-established IPCC procedures in this instance". The date of 2035 has been correctly quoted by the IPCC from the WWF report, which has misquoted its own source, an ICSI report "Variations of Snow and Ice in the past and at present on a Global and Regional Scale".
Rajendra K. Pachauri responded in "Extended Interview: Climate Science Leader Rajendra K. Pachauri Confronts the Critics" by Pallava Bagla, Science (journal) 29 January 2010: Vol. 327. no. 5965, pp. 510 - 511 (DOI: 10.1126/science.327.5965.510); also related wikinews article .
Former IPCC chairman Robert Watson has said "The mistakes all appear to have gone in the direction of making it seem like climate change is more serious by overstating the impact. That is worrying. The IPCC needs to look at this trend in the errors and ask why it happened." Martin Parry, a climate expert who had been co-chair of the IPCC working group II, said that "What began with a single unfortunate error over Himalayan glaciers has become a clamour without substance" and the IPCC had investigated the other alleged mistakes, which were "generally unfounded and also marginal to the assessment".
The third assessment report (TAR) prominently featured a graph labeled "Millennial Northern Hemisphere temperature reconstruction" from a paper by Michael E. Mann, Raymond S. Bradley and Malcolm K. Hughes (MBH98) often referred to as the "Hockey Stick Graph". This graph differed from a schematic in the first assessment report which depicted larger global temperature variations over the past 1000 years, and higher temperatures during the Medieval Warm Period than the present day. (The schematic was not an actual plot of data.) The appearance of MBH98 in the Third Assessment Report was widely construed as demonstrating that the current warming period is exceptional in comparison to temperatures between 1000 and 1900. The methodology used to produce this graph was criticized in a paper by Stephen McIntyre and Ross McKitrick. This criticism was picked up by Republican senator James Inhofe, who calls global warming a "hoax", and it became a focus of political debate. A National Academy of Sciences inquiry requested by the United States Congress agreed that there were some statistical failings, but these had little effect on the graph which was generally correct. The hockey stick graph has been validated by more than 12 reconstructions producing broadly similar results. In a 2006 letter to Nature, Mann, Bradley and Hughes pointed out that their original article had said that "more widespread high-resolution data are needed before more confident conclusions can be reached" and that the uncertainties were "the point of the article."
Some critics have contended that the IPCC reports tend to underestimate dangers, understate risks, and report only the "lowest common denominator" findings.
On February 1, 2007, the eve of the publication of IPCC's major report on climate, a study was published suggesting that temperatures and sea levels have been rising at or above the maximum rates proposed during the last IPCC report in 2001. The study compared IPCC 2001 projections on temperature and sea level change with observations. Over the six years studied, the actual temperature rise was near the top end of the range given by IPCC's 2001 projection, and the actual sea level rise was above the top of the range of the IPCC projection.
An example of scientific research which has indicated that previous estimates by the IPCC, far from overstating dangers and risks, has actually understated them (this may be due, in part, to the expanding human understanding of climate) is a study on projected rises in sea levels. When the researchers' analysis was "applied to the possible scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC), the researchers found that in 2100 sea levels would be 0.5–1.4 m above 1990 levels. These values are much greater than the 9–88 cm as projected by the IPCC itself in its Third Assessment Report, published in 2001.
In reporting criticism by some scientists that IPCC's then-impending January 2007 report understates certain risks, particularly sea level rises, an AP story quoted Stefan Rahmstorf, professor of physics and oceanography at Potsdam University as saying "In a way, it is one of the strengths of the IPCC to be very conservative and cautious and not overstate any climate change risk."
In his December 2006 book, Hell and High Water: Global Warming, and in an interview on Fox News on January 31, 2007, energy expert Joseph Romm noted that the IPCC Fourth Assessment Report is already out of date and omits recent observations and factors contributing to global warming, such as the release of greenhouse gases from thawing tundra.
Political influence on the IPCC has been documented by the release of a memo by ExxonMobil to the Bush administration, and its effects on the IPCC's leadership. The memo led to strong Bush administration lobbying, evidently at the behest of ExxonMobil, to oust Robert Watson, a climate scientist, from the IPCC chairmanship, and to have him replaced by Pachauri, who was seen at the time as more mild-mannered and industry-friendly.
We have some concerns about the objectivity of the IPCC process, with some of its emissions scenarios and summary documentation apparently influenced by political considerations. There are significant doubts about some aspects of the IPCC's emissions scenario exercise, in particular, the high emissions scenarios. The Government should press the IPCC to change their approach. There are some positive aspects to global warming and these appear to have been played down in the IPCC reports; the Government should press the IPCC to reflect in a more balanced way the costs and benefits of climate change. The Government should press the IPCC for better estimates of the monetary costs of global warming damage and for explicit monetary comparisons between the costs of measures to control warming and their benefits. Since warming will continue, regardless of action now, due to the lengthy time lags.
The Stern Review ordered by the UK government, whose findings were released in October 2006, made a stronger argument in favor of urgent action to combat human-made climate change than previous analyses, including some by IPCC. The conclusions of the Stern Review have been contested, however.
The structural elements of the IPCC processes have been criticized in other ways, with the design of the processes during the formation of the IPCC making its reports prone not to exaggerations, but to underestimating dangers, under-stating risks, and reporting only the "least common denominator" findings which by design make it through the bureaucracy. As noted by Spencer Weart, Director of the Center for History of Physics at the American Institute of Physics,
The Reagan administration wanted to forestall pronouncements by self-appointed committees of scientists, fearing they would be 'alarmist.' Conservatives promoted the IPCC's clumsy structure, which consisted of representatives appointed by every government in the world and required to consult all the thousands of experts in repeated rounds of report-drafting in order to reach a consensus. Despite these impediments the IPCC has issued unequivocal statements on the urgent need to act.
Since the IPCC does not carry out its own research, it operates on the basis of scientific papers and independently documented results from other scientific bodies, and its schedule for producing reports requires a deadline for submissions prior to the report's final release. In principle, this means that any significant new evidence or events that change our understanding of climate science between this deadline and publication of an IPCC report cannot be included. In an area of science where our scientific understanding is rapidly changing, this has been raised as a serious shortcoming in a body which is widely regarded as the ultimate authority on the science. However, there has generally been a steady evolution of key findings and levels of scientific confidence from one assessment report to the next.
The submission deadlines for the Fourth Assessment Report (AR4) differed for the reports of each Working Group. Deadlines for the Working Group I report were adjusted during the drafting and review process in order to ensure that reviewers had access to unpublished material being cited by the authors. The final deadline for cited publications was July 24, 2006. The final WG I report was released on April 30, 2007 and the final AR4 Synthesis Report was released on November 17, 2007.
Rajendra Pachauri, the IPCC chair, admitted at the launch of this report that since the IPCC began work on it, scientists have recorded "much stronger trends in climate change", like the unforeseen dramatic melting of polar ice in the summer of 2007, and added, "that means you better start with intervention much earlier".
Scientists who participate in the IPCC assessment process do so without any compensation other than the normal salaries they receive from their home institutions. The process is labor intensive, diverting time and resources from participating scientists' research programs. Concerns have been raised that the large uncompensated time commitment and disruption to their own research may discourage qualified scientists from participating.
In February 2010, in response to controversies regarding claims in the Fourth Assessment Report, five climate scientists - all contributing or lead IPCC report authors - wrote in the journal Nature calling for changes to the IPCC. They suggested a range of new organizational options, from tightening the selection of lead authors and contributors, to dumping it in favor of a small permanent body, or even turning the whole climate science assessment process into a moderated "living" Wikipedia-IPCC. Other recommendations included that the panel employ a full-time staff and remove government oversight from its processes to avoid political interference.
In March 2010, at the invitation of the United Nations secretary-general and the chair of the IPCC, the InterAcademy Panel on International Issues was asked to review  the IPCC's processes for developing its reports. The panel's review would be funded by the UN and would expect to release its findings and recommendations in August 2010.
Various scientific bodies have issued official statements praising the IPCC and endorsing their findings.
|Awards and achievements|
|Nobel Peace Prize Laureate
with Al Gore
|Intergovernmental Panel on Climate Change|
The Intergovernmental Panel on Climate Change (IPCC) is a group of scientists chosen by governments and other large groups from around the world who study the chance that humans may make the Earth heat up unnaturally. The group was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), two organizations of the United Nations.
A lot of IPCC work is publishing reports about the UN Framework Convention on Climate Change (UNFCCC), an international agreement that human inventions and chemistry may make the Earth too warm to live on. The UNFCCC was the beginning of the Kyoto Protocol. Members of the IPCC read, write, and calculate as much as they can. Only member states of the WMO and UNEP may be members of IPCC. A lot of professors trust the IPCC work.
The first IPCC report was published in 1990. More was added to that report in 1992. The second report was published in 1995, the third was published in 2001, and a fourth in 2007. Each report is in three books called Working Groups 1, 2 and 3. Most times "the IPCC report" means the Working Group I report, which is about basic climate change.
The Fourth Assessment Report (AR4) was completed in early 2007. Like earlier IPCC reports, it contains four reports, three of them from its working groups.
Working Group 1 was about the "Physical Science Basis of Climate Change." The Working Group 1 report was published on 2 February, 2007 and revised on 5 February, 2007. There was also a 2 February, 2007 press release. The full Working Group 1 report was published in March. The main report says::
The Third Assessment Report (TAR) contains four reports, three of them from its working groups:
The "headlines" from the Summary for Policymakers in The Scientific Basis were:
The estimate for the climate sensitivity was 1.5 to 4.5 °C; and the average temperature was predicted to increase by 1.4 to 5.8 Celsius degrees between 1990 and 2100, and the sea level was predicted to rise between 0.1 and 0.9 meters. The range of predictions is based on different levels of human carbon dioxide production. Each perdiction has different possible outcomes.
IPCC used the best predictions and their reports were watched by important scientists. The IPCC believed they needed better predictions and better understanding of climate. Some scientists claim the IPCC do not know enough about greenhouse gases to make good predictions.[needs proof]
MIT professor Richard Lindzen, who works for the IPCC Working Group 1, claims some of the IPCC reports are wrong. He told the U.S. Senate Committee on Commerce, Science and Transportation that he was unhappy about the Executive Summary based on his work in May 2001. He said that he told the IPCC they were making mistakes and the Working Group 1 report said that meant they were "making improvements".
Professor Lindzen said:
The summary does not reflect the full document... For example, I worked on Chapter 7, Physical Processes. This chapter dealt with the nature of the basic processes which determine the response of climate, and found numerous problems with model treatments – including those of clouds and water vapor. The chapter was summarized with the following sentence: 'Understanding of climate processes and their incorporation in climate models have improved, including water vapor, sea-ice dynamics, and ocean heat transport.'
The Working Group 1 report said:
Climate Change 1995, the IPCC Second Assessment Report (SAR), was finished in 1996. It was made in four parts:
Each of the working groups was made by its own working group, and each has a Summary for Policymakers (SPM) that is a list of agreements by governments. The Summary for Policy Makers of the Working Group 1 report says:
Three scientists involved in climate research believe that the IPCC reports do not accurately summarize the state of knowledge.
On December 20, 1995, Reuters news agency claimed a British scientist Keith Shine, one of IPCC's most important authors, talking about the Policymakers' Summary, said: "We produce a draft, and then the policymakers go through it line by line and change the way it is presented.... It's peculiar that they have the final say in what goes into a scientists' report". Keith Shine did not say what diffenrences the changes make.
Physicist Frederick Seitz, the President Emeritus of Rockefeller University, said the IPCC report was not good, writing "I have never witnessed a more disturbing corruption of the peer-review process than the events that led to this IPCC report". He opposed it in the Leipzig Declaration of S. Fred Singer's Science and Environmental Policy Project.
Professor Seitzs comments were opposed by the presidents of the American Meteorological Society and University Corporation for Atmospheric Research, who wrote about an effort by some people make it seem that humans had not changed the climate. .
S. Fred Singer said that :
Benjamin D. Santer, Lead Author of Chapter 8 of 1995 IPCC Working Group 1 report, said :
The Second Assessment Report was the only one with a chapter on the economic effect of climate change. This part of the report was thought to be unfair because the value of life in poorer countries was less.
The 1992 supplementary report was an update of the 1990 report, requested for the Framework Convention on Climate Change at the Earth Summit (United Nations Conference on Environment and Development) in Rio de Janeiro in 1992.
It did not make any important changes to the 1990 report. It claimed the prediction methods in the First Assessment Report, were now improved, but did not include aerosol or ozone changes.
The IPCC first assessment report was completed in 1990, and used to make the United Nations Framework Convention on Climate Change (UNFCCC).
The Working Group 1 report says:
The Chairperson of the IPCC is Rajendra K. Pachauri, elected in May 2002; before that Robert Watson headed the IPCC. The chairperson is helped by an elected Bureau including vice-chairpersons, Working Group co-chairpersons and a Secretariat (see below).
The IPCC Panel is made of people from governments and other groups. Scientific experts are preferred. Meetings of the IPCC and IPCC Working Groups are held by members of governments. Non-Governmental and Intergovernmenta Organizations may be allowed to attend as observers. Meetings of the IPCC Bureau, workshops, experts and lead authors are by invitation only. 350 government officials and climate change experts visited the 2003 meeting. The meeting report  says there were 322 persons in attendance at meetings with about seven-eighths of visitors being from governments.
There are several major groups:
The IPCC receives funding from UNEP, WMO, and its own Trust Fund which gets money from governments.
People from over 130 countries contributed to the IPCC Fourth Assessment Report over 6 years. These people included more than 2500 scientific expert reviewers, more than 800 contributing authors, and more than 450 lead authors.
The Working Group 1 report of 2007 (including the summary for policy makers) included contributions by 600 authors from 40 countries, over 620 expert reviewers, a large number of government reviewers, and representatives from 113 governments .
The AR4 Synthesis Report (SYR) was finalized in November 2007. Documentation on the meetings for the AR4 are available , the outlines for the Working Group 1 report PDF (11.5 KiB) and a provisional author list PDF (108 KiB).
The IPCC also supports other activities, such as the Data Distribution Centre  and the National Greenhouse Gas Inventories Programme . This involves estimating greenhouse gas based on the levels of fuel used, industrial production and so on.
The IPCC also answers questions from the UNFCCC Subsidiary Body for Scientific and Technological Advice (SBSTA).
The IPCC reports are a collection of peer reviewed and published science. Each IPCC report explains improvements to the previous report and also explains where more research is needed.
Review comments are open to the public for at least five years.
The Panel controls what the IPCC agrees on to meet standards. The Panel's approval process has been criticized for changing what the experts put in the Reports.
Each chapter has a lot of authors who are responsible for writing and editing the material. A chapter usually has two "Coordinating" Lead Authors who control what words go in their chapter, ten to fifteen Lead Authors, and a larger number of Contributing Authors. The Lead Authors put together the work of the other authors and report to the Working Group chairs. Lead Authors write sections of chapters. Contributing Authors prepare text, graphs and data.
Authors are chosen from a list of researchers prepared by governments, other important groups, the Working Group/Task Force Bureaux, and other experts (PDF (55.7 KiB), 4.2.1,2). The group of Coordinating Lead Authors and Lead Authors for a section or chapter of a Report is expected to have many different views and to have people from different parts of the world.
In December 2007, the IPCC was awarded the The Nobel Peace Prize 2007 "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change." The award is shared with Former U.S. Vice-President Al Gore for his work on climate change and the documentary An Inconvenient Truth.
In January 2005 Christopher Landsea resigned from work on the IPCC AR4, saying that it was "both being motivated by pre-conceived agendas and being scientifically unsound" because of Kevin Trenberth's idea that global warming was contributing to recent hurricane activity . Roger A. Pielke who published Landsea's letter writes: "How anyone can deny that political factors were everpresent in the negotiations isn't paying attention", but says that "Despite the pressures, on tropical cyclones they figured out a way to maintain consistency with the actual balance of opinion(s) in the community of relevant experts." He continues "So there might be a human contribution (and presumably this is just to the observed upwards trends observed in some basins, and not to downward trends observed in others, but this is unclear) but the human contribution itself has not been quantitatively assessed, yet the experts, using their judgment, expect it to be there. In plain English this is what is called a 'hypothesis' and not a 'conclusion.' And it is a fair representation of the issue."
The IPCC Third Assessment Report showed a graph labeled "Millennial Northern Hemisphere temperature reconstruction" from a paper by Mann, Bradley and Hughes (MBH98) often called the "Hockey Stick Graph". This graph was different to the IPCC First assessment report which showed global temperature for the past 1000 years, and higher temperatures during the Medieval Warm Period. The graph was thought to show that temperatures between 1000 and 1900 were very different. This was criticized in an article by Stephen McIntyre and Ross McKitrick. In a 2006 letter to Nature, Bradley, Hughes and Mann claimed the original article had said that they could not be exact.
Some critics say the IPCC reports underestimate dangers, understate risks, and report only the lowest risks.
On February 1 2007, the night before publication of IPCCs report on climate, a study was published saying that temperatures and sea levels have been rising at or above the speed the IPCC reported in 2001. The study compared IPCC 2001 predictions of temperature and sea level change with what actually happened. Over the six years, the actual temperature rise was near the top end of the range given by IPCC's 2001 prediction and the actual rise was more than the top of the range the IPCC predicted.
Political influence on the IPCC has been shown by the release of a memo by ExxonMobil to the Bush administration, and its effects on the IPCCs leadership. The Bush administration, at the request of ExxonMobil, wanted rid of Robert Watson, a climate scientist and IPCC chairperson, and to have him replaced by Pachauri, who was seen at the time as more friendly to industry.
In 2005, the UK House of Lords Select Committee on Economic Affairs produced a report on the economics of climate change. It commented on the IPCC process:
"We have some concerns about the objectivity of the IPCC process, with some of its emissions scenarios and summary documentation apparently influenced by political considerations. There are significant doubts about some aspects of the IPCCs emissions scenario exercise, in particular, the high emissions scenarios. The Government should press the IPCC to change their approach. There are some positive aspects to global warming and these appear to have been played down in the IPCC reports; the Government should press the IPCC to reflect in a more balanced way the costs and benefits of climate change. The Government should press the IPCC for better estimates of the monetary costs of global warming damage and for explicit monetary comparisons between the costs of measures to control warming and their benefits. Since warming will continue, regardless of action now, due to the lengthy time lags.