Intergovernmental Panel on Climate Change
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{{Redirect|IPCC}}
{{Infobox Organization
| name = Intergovernmental Panel on Climate Change [[Image:Nobel prize medal.svg|20px]]
| image = UNFCCC Logo.svg|right|frame|IPCC is the science authority for the [[United Nations Framework Convention on Climate Change|UNFCCC]]
}}
The '''Intergovernmental Panel on Climate Change''' ('''IPCC''') is a scientific body tasked to [[risk management|evaluate 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]].<ref>[http://nobelprize.org/nobel_prizes/peace/laureates/2007/press.html The Nobel Peace Prize for 2007]</ref>
The IPCC does not carry out research, nor does it monitor climate or related phenomena. A main activity of the IPCC is publishing special reports on topics relevant to the implementation of the [[United Nations Framework Convention on Climate Change| UN Framework Convention on Climate Change]] (UNFCCC),<ref name="principles">{{cite web | title=Principles governing IPCC work | date=[[2006-04-28]] | publisher=[[Intergovernmental Panel on Climate Change]] | accessdate=2007-07-24 | url=http://www.ipcc.ch/pdf/ipcc-principales/ipcc-principales.pdf }}</ref> 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. <ref>{{cite web | title=About IPCC – Mandate and Membership of the IPCC | date= | publisher=[[Intergovernmental Panel on Climate Change]] | accessdate=2007-07-24 | url=http://www.ipcc.ch/about/about.htm | year=2007}}</ref> 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.<ref>{{cite web | title=A guide to facts and fiction about climate change | publisher=[[The Royal Society]] | date=March 2005 | accessdate=2007-07-24 | url=http://www.royalsoc.ac.uk/downloaddoc.asp?id=1630 }}</ref><ref>{{cite web | title=The Science of Climate Change | publisher=[[The Royal Society]] | date=[[2001-05-17]] | accessdate=2007-07-24 | url=http://www.royalsoc.ac.uk/displaypagedoc.asp?id=11509 | isbn=0-85403-558-3 }}</ref> National and international responses to climate change generally regard the UN climate panel as authoritative.<ref>{{cite web | title=Scientists offered cash to dispute climate study | date=2007-02-02 | accessdate=2007-07-24 | publisher=[[The Guardian]] | first=Ian | last=Sample | url=http://www.guardian.co.uk/frontpage/story/0,,2004399,00.html | quote=[[Lord Rees of Ludlow]], the president of the [[Royal Society]], Britain's most prestigious scientific institute, said: "The IPCC is the world's leading authority on climate change…"}}</ref>
The summary reports (i.e. ''Summary for Policymakers''), which draw the most media attention, include review by participating governments in addition to scientific review.<ref>[http://www.ipcc.ch/pdf/ipcc-principles/ipcc-principles.pdf Principles Governing IPCC Work]</ref>
{{portal|Energy}}
==Aims==
The principles of the IPCC operation<ref name="principles">IPCC. {{PDFlink|[http://www.ipcc.ch/about/princ.pdf Principles Governing IPCC Work]|8.38 [[Kibibyte|KiB]]<!-- application/pdf, 8582 bytes -->}}. Retrieved [[December 19]] [[2006]].</ref> 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.
{{quotation|The role of the IPCC is to assess on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation. IPCC reports should be neutral with respect to policy, although they may need to deal objectively with scientific, technical and socio-economic factors relevant to the application of particular policies.
Review is an essential part of the IPCC process. Since the IPCC is an intergovernmental body, review of IPCC documents should involve both peer review by experts and review by governments.<ref name="principles"/>}}
<!-- The template generating the following text has been listed for deletion. Please see http://en.wikipedia.org/wiki/Wikipedia:Templates_for_deletion#Template:Editnote for discussion and voting -->
<!-- Editors Note: The "human-induced" phrase has been challenged several times. It is in the IPCC "About" page and the IPCC Principles, and indeed in the quote just above. -->
The stated aims of the IPCC are to assess scientific information relevant to:
# human-induced climate change,
# the impacts of human-induced climate change,
# options for adaptation and mitigation.
The history of the IPCC is described in a {{PDFlink|[http://www.ipcc.ch/pdf/10th-anniversary/anniversary-brochure.pdf brochure]|618 [[Kibibyte|KiB]]<!-- application/pdf, 633705 bytes -->}}. The IPCC has been chaired by [[Rajendra Pachauri]] since 2002.
==IPCC Assessment Reports==
{{IPCC}}
The IPCC published its [[IPCC First Assessment Report|first assessment report]] in 1990, a supplementary report in 1992, a [[IPCC Second Assessment Report|second assessment report (SAR)]] in 1995, and a [[IPCC Third Assessment Report|third assessment report (TAR)]] in 2001. A [[IPCC Fourth Assessment Report|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.
===IPCC Fourth Assessment Report: Climate Change 2007===
{{Main article|IPCC Fourth Assessment Report}}
{| class="wikitable" align="right" border="1" width="180"
| colspan="3" align="center" style="background:#B3B7FF" |The four SRES scenario families <ref>according to: [http://www.cics.uvic.ca/scenarios/index.cgi?More_Info-Emissions Canadian Institute for Climate Studies, CCIS project: ''Frequently Asked Questions '']</ref><ref>[http://www.grida.no/climate/ipcc/emission/091.htm#4.2.1. IPCC Special Report on Emissions Scenarios, Chapter 4: An Overview of Scenarios / 4.2. SRES Scenario Taxonomy / '''Table 4- 2: Overview of SRES scenario quantifications.''']</ref><ref>[http://www.grida.no/climate/ipcc_tar/wg3/081.htm Figure 2.11: Schematic illustration of SRES scenarios (IPCC)]</ref> of the ''Fourth Assessment Report'' vs. associated changes in global-mean temperature until 2100
|-
|<center><small>[http://ipcc-wg1.ucar.edu/wg1/wg1-report.html AR4]</small></center>
|<br/><small>more economic focus</small>
|<br/><small>more environmental focus</small>
|- valign="middle"
|[[Globalisation]]<br /><small>(homogeneous world)</small>
| align="center" |'''A1'''<br /> <small>rapid economic growth</small><br /><small>(groups: A1T/A1B/A1Fl)</small><br />'''1.4 - 6.4 °C'''
| align="center" | '''B1'''<br /><small>global environmental sustainability</small><small> </small><br />'''1.1 - 2.9 °C'''
|- valign="middle"
|[[Regionalisation]]<br /><small>(heterogeneous world)</small>
| align="center" | '''A2'''<br /><small>regionally oriented<br />economic development</small><br />'''2.0 - 5.4 °C'''
| align="center" | '''B2'''<br /><small>local environmental sustainability</small><br />'''1.4 - 3.8 °C'''
|}
The Fourth Assessment Report (AR4) was completed in early 2007<ref name = "">[http://ipcc-wg1.ucar.edu/wg1/wg1_home.html IPCC WG1], UCAR.</ref>. 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 [[2 February]], [[2007]]<ref name="WG1SPM2Feb">{{PDFlink|http://www.ipcc.ch/SPM2feb07.pdf|1.25 [[Mebibyte|MiB]]<!-- application/pdf, 1319065 bytes -->}}</ref> and revised on [[5 February]], [[2007]]<ref name="WG1SPM5Feb">{{PDFlink|[http://ipcc-wg1.ucar.edu/wg1/docs/WG1AR4_SPM_Approved_05Feb.pdf IPCC Summary for Policymakers]|1.25 [[Mebibyte|MiB]]<!-- application/pdf, 1319065 bytes -->}}</ref>. There was also a [[2 February]], [[2007]] press release<ref name = "PRWG">[http://www.ipcc.ch/press/prwg2feb07.htm Press release], IPCC, 2007-02-02.</ref>. The full WGI report<ref name="WG1Full">{{Citation | title=Climate Change 2007: The Physical Sciences Basis| url=http://ipcc-wg1.ucar.edu/wg1/wg1-report.html | publisher=[[IPCC]] | access-date=2007-04-30}}</ref> was published in March. The key conclusions of the SPM were that<ref name = "SPM">{{PDFlink|[http://www.ipcc.ch/SPM2feb07.pdf SPM]|1.25 [[Mebibyte|MiB]]<!-- application/pdf, 1319065 bytes -->}}, IPCC 2007-02-02.</ref>:
*''Warming of the climate system is unequivocal''.
*''Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (human) greenhouse gas concentrations''.
*''Anthropogenic warming and sea level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized,'' although the likely amount of temperature and sea level rise varies greatly depending on the fossil intensity of human activity during the next century (pages 13 and 18)<ref name = WG1SPM5Feb />.
*The probability that this is caused by natural climatic processes alone is less than 5%.<!-- i.e 'external forcing' is the cause -->
*World temperatures could rise by between 1.1 and 6.4 °C (2.0 and 11.5 °F) during the 21st century (table 3) and that:
**Sea levels will probably rise by 18 to 59 cm (7.08 to 23.22 in) [table 3].
**There is a confidence level >90% that there will be more frequent warm spells, [[heat wave]]s and heavy rainfall.
**There is a confidence level >66% that there will be an increase in [[drought]]s, tropical [[cyclone]]s and extreme [[high tide]]s.
*Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium.
*''Global atmospheric concentrations of [[carbon dioxide]], [[methane]], and [[nitrous oxide]] have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values'' over the past 650,000 years
In IPCC statements "most" means greater than 50%, "likely" means at least a 66% likelihood, and "very likely" means at least a 90% likelihood.
An outline of chapters in the WGI report (as of November 3, 2005)<ref name = "wg1outline">{{PDFlink|[http://ipcc-wg1.ucar.edu/wg1/docs/wg1_AuthorList_2005-11-03.pdf Outline of IPCC WG1 chapters as of November 3, 2005]|21.8 [[Kibibyte|KiB]]<!-- application/pdf, 22326 bytes -->}} </ref> and a list of the report's authors (as of March 10, 2005)<ref name = "wg1authors">{{PDFlink|[http://ipcc-wg1.ucar.edu/wg1/docs/wg1_outline.pdf List of IPCC WG1 authors, as of March 10, 2005]|134 [[Kibibyte|KiB]]<!-- application/pdf, 137508 bytes -->}}</ref> were made available before publication of the SPM.
The Summary for Policymakers for the Working Group II [http://www.ipcc-wg2.org/index.html] report was released on April 6, 2007<ref>Working Group II Contribution to the
Intergovernmental Panel on Climate Change Fourth Assessment Report Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability: {{PDFlink|http://www.ipcc.ch/SPM6avr07.pdf|547 [[Kibibyte|KiB]]<!-- application/pdf, 560645 bytes -->}} (23 page PDF file)</ref>.
The Summary for Policymakers for the Working Group III report <ref>{{cite web|url=http://www.ipcc.ch/SPM040507.pdf|title=WG III Summary for Policymakers: Mitigation of Climate Change|accessdate=2007-05-04}}</ref> was released on May 4, 2007.
The AR4 Synthesis Report (SYR) was released on November 17, 2007.
===IPCC Third Assessment Report: Climate Change 2001===
{{Main article|IPCC Third Assessment Report}}
The Third Assessment Report (TAR) consists of four reports, three of them from its working groups:
* Working Group I: The Scientific Basis<ref name = "IPCC WG1">[http://www.grida.no/climate/ipcc_tar/wg1/index.htm Working Group 1], IPCC.</ref>
* Working Group II: Impacts, Adaptation and Vulnerability<ref name = "IPCC WG2">[http://www.grida.no/climate/ipcc_tar/wg2/index.htm Working Group 2], IPCC.</ref>
* Working Group III: Mitigation<ref name = "IPCC WG3">[http://www.grida.no/climate/ipcc_tar/wg3/index.htm Working Group 3], IPCC.</ref>
* Synthesis Report<ref name = "IPCC Synth">[http://www.grida.no/climate/ipcc_tar/vol4/index.htm Synthesis Report], IPCC.</ref>
The "headlines" from the Summary for Policymakers<ref name = "Headlines">[http://www.grida.no/climate/ipcc_tar/wg1/005.htm Headlines], IPCC.</ref> in ''The Scientific Basis'' were:
#An increasing body of observations gives a collective picture of a warming world and other changes in the climate system (The [[temperature record|global average surface temperature]] has increased over the 20th century by about 0.6 °C; Temperatures have risen during the past four decades in the lowest 8 kilometers of the atmosphere; Snow cover and ice extent have decreased)
#Emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate (Anthropogenic aerosols are short-lived and mostly produce negative [[radiative forcing]]; Natural factors have made small contributions to radiative forcing over the past century)
#Confidence in the ability of models to project future climate has increased (Complex physically based climate models are required to provide detailed estimates of feedback and of regional features. Such models cannot yet simulate all aspects of climate (e.g., they still cannot account fully for the observed trend in the surface-troposphere temperature difference since 1979) and there are particular uncertainties associated with clouds and their interaction with radiation and aerosols. Nevertheless, confidence in the ability of these models to provide useful projections of future climate has improved due to their demonstrated performance on a range of space and time-scales<ref name = "WG1 7">[http://www.grida.no/climate/ipcc_tar/wg1/007.htm Working Group 1], IPCC.</ref>.)
#There is new and stronger evidence that most of the warming observed over the past 50 years is attributable to human activities
#Human influences will continue to change atmospheric composition throughout the 21st century
#Global average temperature and sea level are projected to rise under all IPCC [[Special Report on Emissions Scenarios|SRES scenarios]]
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 [[Special Report on Emissions Scenarios|scenarios]] that assume different levels of future CO<sub>2</sub> emissions. Each scenario then has a range of possible outcomes associated with it. The most optimistic outcome assumes an aggressive campaign to reduce CO<sub>2</sub> emissions; the most pessimistic is a "business as usual" scenario. Other scenarios fall in between.{{Fact|date=July 2007}}
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 gas]]es 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.{{Fact|date=July 2007}}
====Economic growth estimates debate====
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.<ref>Castles and Henderson (2003), Energy & Environment, 14:159-185</ref> 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.<ref>{{cite web|url=http://www.ingentaconnect.com/search/article?author=Nakicenovic&year_from=2002&year_to=2007&database=1&pageSize=20&index=2|title=IPCC SRES Revisited: A Response|accessdate=2007-05-01}}</ref> See the discussion under [[Special Report on Emissions Scenarios]].
<!-- The given reference does support the first part of the sentence (Castles and Henderson asserted inflated growth rates), but not the second part (this results in increased emissions estimates). -->
====Physical modeling debate====
{{See also|global climate model}}
[[Massachusetts Institute of Technology|MIT]] professor [[Richard Lindzen]], one of the scientists in IPCC Working Group I, has expressed disagreement with the IPCC reports. He expressed his unhappiness about those portions in the Executive Summary based on his contributions in May 2001 before the [[U.S. Senate Committee on Commerce, Science and Transportation]]:
{{quotation|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.'<ref>{{cite web | title=Testimony of Richard S. Lindzen before the U.S. Senate Commerce Committee | first=Richard S. | last=Lindzen | authorlink=Richard Lindzen | url=http://www.john-daly.com/TAR2000/lindzen.htm | publisher=john-daly.com | date=[[May 1]], [[2001]] | accessdate=2007-08-29 }}</ref>}}
The Summary for Policymakers of the WG1 reports ''does'' include caveats on model treatments: ''Such models cannot yet simulate all aspects of climate (e.g., they still cannot account fully for the observed trend in the surface-troposphere temperature difference since 1979) and there are particular uncertainties associated with clouds and their interaction with radiation and aerosols. Nevertheless, confidence in the ability of these models to provide useful projections of future climate has improved due to their demonstrated performance on a range of space and time-scales.'' [http://www.grida.no/climate/ipcc_tar/wg1/007.htm].
These statements are in turn supported by the executive summary of chapter 8 of the report, which includes:
* ''Coupled models can provide credible simulations of both the present annual mean climate and the climatological seasonal cycle over broad continental scales for most variables of interest for climate change. Clouds and humidity remain sources of significant uncertainty but there have been incremental improvements in simulations of these quantities''.
* ''Confidence in the ability of models to project future climates is increased by the ability of several models to reproduce the warming trend in 20th century surface air temperature when driven by radiative forcing due to increasing greenhouse gases and sulphate aerosols. However, only idealised scenarios of only sulphate aerosols have been used''.
===IPCC Second Assessment Report: Climate Change 1995===
{{Main article|IPCC Second Assessment Report}}
''Climate Change 1995'', the IPCC Second Assessment Report (SAR), was finished in 1996. It is split into four parts:
* A synthesis to help interpret [[UNFCCC]] article 2.
* ''The Science of Climate Change'' (WG I)
* ''Impacts, Adaptations and Mitigation of Climate Change'' (WG II)
* ''Economic and Social Dimensions of Climate Change'' (WG III)
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:
# Greenhouse gas concentrations have continued to increase
# Anthropogenic aerosols tend to produce negative radiative forcings
# Climate has changed over the past century (air temperature has increased by between 0.3 and 0.6 °C since the late 19th century; this estimate has not significantly changed since the 1990 report).
# The balance of evidence suggests a discernible human influence on global climate (considerable progress since the 1990 report in distinguishing between natural and anthropogenic influences on climate, because of: including aerosols; coupled models; pattern-based studies)
# Climate is expected to continue to change in the future (increasing realism of simulations increases confidence; important uncertainties remain but are taken into account in the range of model projections)
# There are still many uncertainties (estimates of future emissions and biogeochemical cycling; models; instrument data for model testing, assessment of variability, and detection studies)
==== Debate ====
A [[December 20]], [[1995]], Reuters report quoted British scientist [[Keith Shine]], one of IPCC's lead authors, discussing the Policymakers' Summary. He 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 physics|Solid-state physicist]] [[Frederick Seitz]], president emeritus of Rockefeller University and past president of the National Academy of Sciences, has 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'' [http://www.ucar.edu/communications/quarterly/summer96/insert.html].
[[S. Fred Singer]] disseminated a letter about Chapter 8, asserting that [http://web.archive.org/web/19980629122454/http://www.sepp.org/ipcccont/ipccflap.htm]:
# Chapter 8 was altered substantially to make it conform to the Summary;
# Three key clauses — expressing the consensus of authors, contributors, and reviewers — should have been placed into the Summary instead of being deleted from the approved draft chapter;
[[Benjamin D. Santer]], Convening Lead Author of Chapter 8 of 1995 IPCC Working Group I Report, replied [http://web.archive.org/web/19981202173029/http://www.sepp.org/ipcccont/Item08.htm]:
# All revisions were made with the sole purpose of producing the best-possible and most clearly explained assessment of the science, and were under the full scientific control of the Convening Lead Author of Chapter 8.
# None of the changes were politically motivated.
====Debate over value of a statistical life====
The Second Assessment Report was the first and last to include a chapter on the economic impacts of climate change, of which impacts on human mortality are an important part. As is customary in environmental economics, health impacts of climate change are valued on the basis of willingness to pay for risk reduction. The advantage of this method is that health risks of climate change are treated like any other health risk. The disadvantage of this method is that health risks in different parts of the world are valued differently. Specifically, the value of a statistical life is much higher in rich countries than in poor countries. The chapter authored by [[David Pearce (economist)| David Pearce]], Amrita Achanta, Bill Cline, Sam Fankhauser, [[Rajendra K. Pachauri| Rajendra Pachauri]], [[Richard Tol]], and [[Pier Vellinga]] faithfully reflected the state of the art of the literature, but the chapter was attacked: the IPCC was accused of [[blasphemy]] and David Pearce's offices were occupied.<ref>F. Pearce (1995), 'Global Row over Value of Human Life', New Scientist, August 19, 7.</ref><ref>E. Masood (1995), 'Developing Countries Dispute Use of Figures on Climate Change Impact', Nature, 376, 374.</ref><ref>E. Masood and A. Ochert (1995), 'UN Climate Change Report Turns up the Heat', Nature, 378, 119.</ref><ref>A. Meyer (1995), 'Economics of Climate Change', Nature, 378, 433.</ref><ref>N. Sundaraman (1995), 'Impact of Climate Change', Nature, 377, 472.</ref><ref>T. O'Riordan (1997), 'Review of Climate Change 1995 -- Economic and Social Dimension', Environment, 39 (9), 34-39.</ref> This chapter is the only instance in which the authors of the chapter officially denounced the policy makers' summary for inaccuracy.<ref>[http://yosemite.epa.gov/ee/epalib/nwlet.nsf/434d5673ac53b154852564cd007a8a0d/716e9f1d6b29a006852564d600141f3a!OpenDocument National Center for Environmental Economics]</ref>
===IPCC Supplementary Report: 1992===
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.
===IPCC First Assessment Report: 1990===
{{main|IPCC First Assessment Report}}
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 includes:
*We are certain of the following: there is a natural greenhouse effect...; emissions resulting from human activities are substantially increasing the atmospheric concentrations of the greenhouse gases: CO<sub>2</sub>, methane, CFCs and nitrous oxide. These increases will enhance the greenhouse effect, resulting on average in an additional warming of the Earth's surface. The main greenhouse gas, water vapour, will increase in response to global warming and further enhance it.
*We calculate with confidence that: ...CO<sub>2</sub> has been responsible for over half the enhanced greenhouse effect; long-lived gases would require immediate reductions in emissions from human activities of over 60% to stabilise their concentrations at today's levels...
*Based on current models, we predict: under [BAU] increase of global mean temperature during the [21st] century of about 0.3 <sup>o</sup>C per decade (with an uncertainty range of 0.2 to 0.5 <sup>o</sup>C per decade); this is greater than that seen over the past 10,000 years; under other ... scenarios which assume progressively increasing levels of controls, rates of increase in global mean temperature of about 0.2 <sup>o</sup>C [to] about 0.1 <sup>o</sup>C per decade.
*There are many uncertainties in our predictions particularly with regard to the timing, magnitude and regional patterns of climate change, due to our incomplete understanding of: sources and sinks of GHGs; clouds; oceans; polar ice sheets.
*Our judgement is that: global mean surface air temperature has increased by 0.3 to 0.6 <sup>o</sup>C over the last 100 years...; The size of this warming is broadly consistent with prediction of climate models, but it is also of the same magnitude as natural climate variability. Thus the observed increase could be largely due to this natural variability; alternatively this variability and other human factors could have offset a still larger human-induced greenhouse warming. The unequivocal detection of the enhanced greenhouse effect is not likely for a decade or more.
===IPCC Methodology Reports===
Within IPCC the [http://www.ipcc-nggip.iges.or.jp/ 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:
*to develop and refine an internationally-agreed methodology and software for the calculation and reporting of national GHG emissions and removals; and
*to encourage the widespread use of this methodology by countries participating in the IPCC and by signatories of the United Nations Framework Convention on Climate Change (UNFCCC).
====Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories====
The [http://www.ipcc-nggip.iges.or.jp/public/gl/invs1.html Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories] (1996 GLs) provide the methodological basis for the estimation of a ational [[greenhouse gas]] [[emission inventory]]. Over time these 1996GLs have been completed with guidance on so-called "Good Practice":
*[http://www.ipcc-nggip.iges.or.jp/public/gp/english/index.html Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories]; and
*[http://www.ipcc-nggip.iges.or.jp/public/gpglulucf/gpglulucf.html Good Practice Guidance for Land Use,Land-Use Change and Forestry]
Together the 1996 GLs and both good practice reports are to be used by parties to the [[UNFCCC]] and to the [[Kyoto Protocol]] in their annual submissions of national greenhouse gas inventories
====2006 IPCC Guidelines for National Greenhouse Gas Inventories====
The 2006 IPCC Guidelines for National Greenhouse Gas Inventories ([http://www.ipcc-nggip.iges.or.jp/public/2006gl/index.html 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]].
==Operations==
The Chair of the IPCC is [[Rajendra K. Pachauri]], elected in May 2002; previously [[Robert Watson (scientist)|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 group|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.<ref>IPCC. [http://www.ipcc.ch/meet/meet.htm Official documents]. Retrieved December 2006.</ref> Attendance at the 2003 meeting included 350 government officials and climate change experts. After the opening ceremonies, closed plenary sessions were held.<ref>IPCC. {{PDFlink|[http://www.ipcc.ch/meet/session20/finalreport20.pdf Report on the Twentieth Session of the IPCC]|379 [[Kibibyte|KiB]]<!-- application/pdf, 388309 bytes -->}}. [[February 19]] [[2006]]. Retrieved [[December 20]] [[2006]].</ref> The meeting report <ref>IPCC. {{PDFlink|[http://www.ipcc.ch/meet/drepipcc20att-a.pdf Twentieth Session]|127 [[Kibibyte|KiB]]<!-- application/pdf, 130633 bytes -->}}. [[February 19]] [[2006]]. Retrieved [[December 20]] [[2006]].</ref> states there were 322 persons in attendance at Sessions with about seven-eighths of participants being from governmental organizations.<ref>IPCC. {{PDFlink|[http://www.ipcc.ch/meet/drepipcc20att-a.pdf Twentieth Session]|127 [[Kibibyte|KiB]]<!-- application/pdf, 130633 bytes -->}}. [[February 19]] [[2006]]. Retrieved [[December 20]] [[2006]].</ref>
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.<ref>IPCC. [http://www.ipcc.ch/about/about.htm Mandate and Membership of IPCC]. Retrieved [[December 20]] [[2006]].</ref>
There are several major groups:
* IPCC Panel: Meets in plenary session about once a year and controls the organization's structure, procedures, and work programme. The Panel is the IPCC corporate entity.
* Chair: Elected by the Panel.
* Secretariat: Oversees and manages all activities. Supported by [[UNEP]] and [[WMO]].
* Bureau: Elected by the Panel. Chaired by the Chair. 30 members include IPCC Vice-Chairs, Co-Chairs and Vice-Chairs of Working Groups and Task Force.
* Working Groups: Each has two Co-Chairs, one from the developed and one from developing world, and a technical support unit.
** Working Group I: Assesses scientific aspects of the climate system and climate change.
** Working Group II: Assesses vulnerability of socio-economic and natural systems to climate change, consequences, and adaptation options.
** Working Group III: Assesses options for limiting greenhouse gas emissions and otherwise mitigating climate change.
* Task Force on National Greenhouse Gas Inventories
The IPCC receives funding from UNEP, WMO, and its own Trust Fund for which it solicits contributions from governments.
===Contributors===
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<ref>[http://www.ipcc.ch/pdf/press-ar4/ipcc-flyer-low.pdf Press flyer announcing 2007 report] IPCC</ref>.
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 <ref>[http://www.klima-aktiv.com/article96_3033.html Working Group I press release] IPCC via a copy at KlimaAktiv.com</ref>.
==Activities==
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 [[United Nations Framework Convention on Climate Change|UN Framework Convention on Climate Change]] process.<ref name="principles" />
In April 2006, the IPCC released the ''[[IPCC Fourth Assessment Report]]'' or AR4.<ref>IPCC. [http://www.ipcc.ch/activity/ar.htm#ar4 Activities — Assessment Reports]. Retrieved [[December 20]] [[2006]].</ref> Reports of the workshops held so far are available at the IPCC website.<ref>IPCC. [http://www.ipcc.ch/activity/workshops.htm Activities — Workshops & Expert Meetings]. Retrieved December 20 2006.</ref>
* Working Group I [http://ipcc-wg1.ucar.edu/wg1/wg1_home.html]:
** Report was due to be finalized during February of 2007 [http://www.ipcc.ch/press/pr02052006.htm] and was finished on schedule.
** By May 2005, there had been 3 AR4 meetings, with only public information being meeting locations, an author list, one invitation, one agenda, and one list of presentation titles.
** By December 2006, governments were reviewing the revised summary for policy makers.
* Working Group II [http://www.gtp89.dial.pipex.com/index.htm]:
** Report was due to be finalized in mid-2007 and was completed on schedule.
** In May 2005, there had been 2 AR4 meetings, with no public information released.
** One shared meeting with WG III had taken place, with a published summary.
* Working Group III [http://www.rivm.nl/mnp/ieweb/ipcc/index.html]:
** Report was due to be finalized in mid-2007.
** In May 2005, there had been 1 AR4 meeting, with no public information released.
The AR4 Synthesis Report (SYR) was finalized in November 2007. Documentation on the scoping meetings for the AR4 are available [http://www.ipcc.ch/meet/ar4scope.htm] as are the outlines for the WG I report {{PDFlink|[http://www.ipcc.ch/activity/wg1outlines.pdf]|11.5 [[Kibibyte|KiB]]<!-- application/pdf, 11830 bytes -->}} and a provisional author list {{PDFlink|[http://www.ipcc.ch/activity/wg1authors.pdf]|108 [[Kibibyte|KiB]]<!-- application/pdf, 111092 bytes -->}}.
While the preparation of the assessment reports is a major IPCC function, it also supports other activities, such as the Data Distribution Centre [http://www.ipcc-data.org/] and the National Greenhouse Gas Inventories Programme [http://www.ipcc-nggip.iges.or.jp/], required under the [[UNFCCC]]. This involves publishing default [[emission factor]]s, 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)'''.
==Publications==
===Scope and preparation of the reports===
The IPCC reports are a compendium of [[peer review]]ed 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 {{PDFlink|[http://www.ipcc.ch/about/app-a.pdf]|55.7 [[Kibibyte|KiB]]<!-- application/pdf, 57048 bytes -->}}:
* Expert review (6-8 weeks)
* Government/expert review
* Government review of:
** Summaries for Policymakers
** Overview Chapters
** Synthesis Report
Review comments are in an open archive for at least five years.
There are several types of endorsement which documents receive {{PDFlink|[http://www.ipcc.ch/about/app-a.pdf]|55.7 [[Kibibyte|KiB]]<!-- application/pdf, 57048 bytes -->}}:
* '''approval''': Material has been subjected to detailed, line by line discussion and agreement.
** Working Group Summaries for Policymakers are ''approved'' by their Working Groups.
** Synthesis Report Summary for Policymakers is ''approved'' by Panel.
* '''adoption''': Endorsed section by section (and not line by line).
** Panel ''adopts'' Overview Chapters of Methodology Reports.
** Panel ''adopts'' IPCC Synthesis Report.
* '''acceptance''': Not been subject to line by line discussion and agreement, but presents a comprehensive, objective, and balanced view of the subject matter.
** Working Groups ''accept'' their reports.
** Task Force Reports are ''accepted'' by the Panel.
** Working Group Summaries for Policymakers are ''accepted'' by the Panel after group ''approval''.
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.
===Authors===
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 ({{PDFlink|[http://www.ipcc.ch/about/app-a.pdf]|55.7 [[Kibibyte|KiB]]<!-- application/pdf, 57048 bytes -->}}, 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).
==Nobel Peace Prize 2007==
{{wikisource|Al Gore's Nobel Peace Prize acceptance speech}}
In December 2007, the IPCC was awarded 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]]''.<ref name="nobelpeaceprize">{{cite web
| url = http://nobelprize.org/nobel_prizes/peace/laureates/2007/
| title = 2007 Nobel Peace Prize Laureates
| accessdate = 11 October
| accessyear = 2007
|
}}</ref>
==Criticism of IPCC==
===Christopher Landsea resignation===
{{main|IPCC Fourth Assessment Report}}
In January 2005 [[Christopher Landsea]] resigned from work on the [[IPCC Fourth Assessment Report|IPCC AR4]], saying that he viewed the process "as both being motivated by pre-conceived agendas and being scientifically unsound" because of [[Kevin Trenberth]]'s public contention that global warming was contributing to recent hurricane activity <ref>[http://sciencepolicy.colorado.edu/prometheus/archives/science_policy_general/000318chris_landsea_leaves.html Chris Landsea Leaves]</ref>. [[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 notes that the actual report "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."<ref>[http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/001085follow_up_ipcc_and_.htmlFollow Up: IPCC and Hurricanes]</ref>
===Emphasis of the "hockey stick" graph===
{{main|Hockey stick controversy}}
The [[IPCC Third Assessment Report|third assessment report (TAR)]] prominently featured<ref>{{citation
| title=What is the Hockey Stick Debate About
| first1=Ross | last1=McKitrick
| author2-link=Ross McKitrick
| url=http://www.climatechangeissues.com/files/PDF/conf05mckitrick.pdf
| format=PDF
}}</ref> a graph labeled "Millennial Northern Hemisphere temperature reconstruction" from a paper by [[Michael Mann (scientist)|Mann]], Bradley and Hughes (MBH98<ref name=MBH98>{{citation
| title=Global-scale temperature patterns and climate forcing over the past six centuries
| first1=Michael E. | last1=Mann
| first2=Raymond S. | last2=Bradley
| first3=Malcolm K. | last3=Hughes
| author1-link=Michael Mann (scientist)
| author2-link=Raymond Bradley
| journal=[[Nature (journal)|Nature]]
| volume=392 | pages=779-787 | year=1998
| url=http://www.caenvirothon.com/Resources/Mann,%20et%20al.%20Global%20scale%20temp%20patterns.pdf
| format=PDF
}}</ref>) often referred to as the "Hockey Stick Graph". This graph differed from a schematic in the [[MWP and LIA in IPCC reports|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 TAR 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 an article by [[Stephen McIntyre]] and [[Ross McKitrick]].<ref name=MM05a>{{citation
| title=Hockey sticks, principal components, and spurious significance
| first1=Stephen | last1=McIntyre
| first2=Ross | last2=McKitrick
| author1-link=Stephen McIntyre
| author2-link=Ross McKitrick
| journal=[[Geophysical Research Letters]]
| volume=32 | year=2005
| url=http://www.climate2003.com/pdfs/2004GL012750.pdf
| doi=10.1029/2004GL021750
| format=PDF
}}</ref> In a 2006 letter to ''[[Nature (journal)|Nature]]'', Bradley, Hughes and Mann 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."<ref>{{Citation | url=http://www.nature.com/doifinder/10.1038/442627b | title=Authors were clear about hockey-stick uncertainties | first1=Raymond S. | last1=Bradley | first2=Malcolm K. | last2=Hughes | first3=Michael E. | last3=Mann | author1-link=Ray Bradley | author3-link=Michael Mann (scientist) |publication=[[Nature (journal)|Nature]] | volume=442 | issue=7103 | pages=627 | year=2006 | doi=10.1038/442627b }}</ref>
===Conservative nature of IPCC reports===
Some critics have contended that the IPCC reports tend to underestimate dangers, understate risks, and report only the "lowest common denominator" findings.<ref>[http://www.nybooks.com/articles/19981 Warning on Warming - The New York Review of Books<!-- Bot generated title -->]</ref>
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.<ref name = "BBC 1">{{cite web | url=http://news.bbc.co.uk/2/hi/science/nature/6321351.stm | title=Humans blamed for climate change | date=2007-02-02 | first=Richard | last=Black | publisher=[[BBC News]] | accessdate=2007-07-24 }}</ref> 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 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, as well as to the conservative bias, noted above, which is built into the IPCC system,) 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.<ref name = "BBC 2">{{cite web | url=http://news.bbc.co.uk/2/hi/science/nature/6179409.stm | title=Sea level rise 'under-estimated' | date=2006-12-14 | publisher=[[BBC News]] | accessdate=2007-07-24 }}</ref><ref name = "Telegraph">{{cite web | title=London-on-Sea: the future of a city in decay | date=2006-12-28 | accessdate=2007-07-24 | url=http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2006/12/27/nlondon27.xml | first=Roger | last=Highfield | publisher=[[Telegraph.co.uk]] }}</ref>
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 Ramstorf, professor of physics and oceanography at Potsdam University as saying:
{{quotation|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|[[Stefan Rahmstorf]]<ref>{{cite web | title=Climate change: The scientific basis | date=2007-02-05 | accessdate=2007-07-24 | url=http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20070129/ipcc_faq_070129/20070129?hub=SciTech | publisher=[[CTV Television Network]] }}</ref> }}
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.<ref> [http://climateprogress.org/2007/02/01/climate-progress-on-fox-news/ Fox interview]</ref>
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 (scientist)|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.<ref name = "New Scientist">{{cite web | title=Top climate scientist ousted | date=2002-04-19 | publisher=[[New Scientist]] | first=Fred | last=Pearce | url=http://www.newscientist.com/article.ns?id=dn2191 | accessdate=2007-07-24 }}</ref><ref name = "Common Dreams">{{cite web | title=US and Oil Lobby Oust Climate Change Scientist | date=2002-04-20 | accessdate=2007-07-24 | first=Julian | last=Borger | url=http://www.guardian.co.uk/bush/story/0,7369,687650,00.html | publisher=[[The Guardian]] }}</ref>
===IPCC processes===
In 2005, the UK [[House of Lords]] [[Select Committee (Westminster System)|Select Committee]] on Economic Affairs produced a report on the economics of climate change. It commented on the IPCC process:
{{quotation|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.|[http://www.publications.parliament.uk/pa/ld200506/ldselect/ldeconaf/12/12i.pdf ''The Economics of Climate Change'']<small>[[Portable Document Format|PDF]]</small>}}
Interestingly, 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.<ref>See [[Stern Review| main article on Stern Review]]</ref>
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,
{{quotation|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.|[http://www.hnn.us/articles/30148.html]}}
===Outdatedness of reports===
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.<ref>[http://www.carbonequity.info/PDFs/Arctic.pdf Example of concerns over outdatedness of IPCC reports, see p.3]</ref> 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.<ref>[http://ipcc-wg1.ucar.edu/wg1/docs/PublicationDeadlines_2006-07-01.pdf Guidelines for inclusion of recent scientific literature in the Working Group I Fourth Assessment Report.]</ref> 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<ref>[http://www.carbonequity.info/docs/arctic.html Carbon Equity report on the Arctic summer of 2007]</ref>, and added, "that means you better start with intervention much earlier".<ref>[http://www.iht.com/articles/2007/11/18/europe/climate.php Pachauri comments on worsening climate trends]</ref>
===Burden on participating scientists===
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.<ref>{{Citation | title=Analysis of Global Change Assessments: Lessons Learned | author1=Committee on Analysis of Global Change Assessments| author2=Board on Atmospheric Sciences and Climate | author3=Division of Earth and Life Sciences | access-date=2007-07-24 | year=2007 | publisher=[[National Academies Press]] | url=http://www.nap.edu/catalog/11868.html#toc}}</ref> Concerns have been raised that the large uncompensated time commitment and disruption to their own research may discourage qualified scientists from participating.<ref>{{Citation | title=Climate Change Science: An Analysis of Some Key Questions | url=http://www.nap.edu/html/climatechange/index.html| publisher=[[National Academies Press]] | date= | isbn=0-309-07574-2 | first1=Ralph J. | last1=Cicerone | first2=Eric J. | last2=Barton | first3=Robert E. | last3=Dickinson | first4=Inez Y. | last4=Fung | first5=James E. | last5=Hansen | first6=Thomas R. | last6=Karl | first7=Richard S. | last7=Lindzen | first8=James C. | last8=McWilliams | first9=F. Sherwood | last9=Rowland | first10=Edward S. | last10=Sarachik | first11=John M. | last11=Wallace | author1-link=Ralph J. Cicerone | author5-link=James E. Hansen | author6-link=Richard S. Lindzen | accessdate=2007-07-24 | contribution=Assessing Progress in Climate Science | contribution-url=http://www.nap.edu/html/climatechange/7.html | year=2001}}</ref>
==See also==
* [[Avoiding Dangerous Climate Change]] – international conference (2005)
* [[Global warming]]
* [[List of scientists opposing the mainstream scientific assessment of global warming]]
* [[G8+5]]
* [[Summary for policymakers]] <!-- which needs to be merged into here -->
* [[Post-Kyoto Protocol negotiations on greenhouse gas emissions]]
* [[Bert Bolin]]
* [[Renewable Energy Sources and Climate Change Mitigation]]
==Notes and references==
{{reflist|2}}
==External links==
* [http://www.ipcc.ch/ The IPCC web site]
** [http://www.ipcc.ch/about/bureau.htm IPCC Organisation]
** {{PDFlink|[http://www.ipcc.ch/about/princ.pdf IPCC Principles]|8.38 [[Kibibyte|KiB]]<!-- application/pdf, 8582 bytes -->}}
** [http://www.ipcc.ch/pub/pub.htm IPCC publications]
** [http://ipcc-wg1.ucar.edu/ IPCC AR4 WG1 Report Available for Purchase]
*** Summaries for Policymakers (SPMs) of the [[IPCC Fourth Assessment Report]]:
**** {{PDFlink|[http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf Working Group I (The Physical Science Basis)] |3.67 [[Mebibyte|MiB]]<!-- application/pdf, 3855701 bytes -->}},
**** {{PDFlink|[http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-spm.pdf Working Group II (Impacts, Adaptation and Vulnerability]|923 [[Kibibyte|KiB]]<!-- application/pdf, 945567 bytes -->}}
**** {{PDFlink|[http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-spm.pdf Working Group III (Mitigation of Climate Change)]|631 [[Kibibyte|KiB]]<!-- application/pdf, 646521 bytes -->}}
* A [http://www.greenfacts.org/en/climate-change-ar4/ summary of the Fourth Assessment Report SPMs] by [[GreenFacts]].
* [http://www.eoearth.org/article/Intergovernmental_Panel_on_Climate_Change_(IPCC) IPCC article] at the Encyclopedia of Earth - General overview of the IPCC
* [http://www.manicore.com/anglais/documentation_a/greenhouse/IPCC.html Climate Change - What Is the IPCC] by Jean-Marc Jancovici
*[http://www.vega.org.uk/video/programme/119 Climate Change] Freeview Video Interview 2006 - Sherwood Rowland, Nobel Laureate (1995) for work on ozone depletion discusses climate change. Provided by the Vega Science Trust.
{{Nobel Peace Prize Laureates 2001-2025}}
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[[hu:Éghajlat-változási Kormányközi Testület]]
[[ms:Panel Antara Kerajaan tentang Perubahan Cuaca]]
[[nl:Intergovernmental Panel on Climate Change]]
[[ja:気候変動に関する政府間パネル]]
[[no:FNs klimapanel]]
[[nn:FN sitt klimapanel]]
[[pl:Intergovernmental Panel on Climate Change]]
[[pt:Painel Intergovernamental sobre Mudanças Climáticas]]
[[ro:IPCC]]
[[ru:Межправительственная группа экспертов по изменению климата]]
[[scn:Intergovernmental Panel on Climate Change]]
[[simple:Intergovernmental Panel on Climate Change]]
[[sh:Intergovernmental Panel on Climate Change]]
[[fi:IPCC]]
[[sv:Intergovernmental Panel on Climate Change]]
[[th:คณะกรรมการระหว่างรัฐบาลว่าด้วยการเปลี่ยนแปลงสภาพภูมิอากาศ]]
[[vi:Ủy ban Liên chính phủ về Thay đổi Khí hậu]]
[[tr:Hükümetlerarası İklim Değişikliği Paneli]]
[[uk:Міжнародна група експертів з питань змін клімату]]
[[zh-yue:IPCC]]
[[zh:政府間氣候變化專門委員會]]