101-607: The Fifth Assessment Report ( AR5 ) of the United Nations Intergovernmental Panel on Climate Change (IPCC) is the fifth in a series of such reports and was completed in 2014. As had been the case in the past, the outline of the AR5 was developed through a scoping process which involved climate change experts from all relevant disciplines and users of IPCC reports, in particular representatives from governments. Governments and organizations involved in
202-621: A Frequently Asked Questions section. This section of the report, Climate Change 2007: The Physical Science Basis , assessed current scientific knowledge of "the natural and human drivers of climate change" as well as observed changes in climate. It looked at the ability of science to attribute changes to different causes, and made projections of future climate change. It was produced by 676 authors (152 lead authors, 26 review editors, and 498 contributing authors) from 40 countries, then reviewed by over 625 expert reviewers. More than 6,000 peer-reviewed publications were cited. Before being approved,
303-399: A carbon price of up to US$ 50/t, and that nuclear power can rise from 16% to 18%. They also warn that higher oil prices might lead to the exploitation of high-carbon alternatives such as oil sands , oil shales , heavy oils , and synthetic fuels from coal and gas, leading to increasing emissions, unless carbon capture and storage technologies are employed. In the transport sector there
404-471: A "large shift in the pattern of investment, although the net additional investment required ranges from negligible to 5–10%".They also concluded that it is often more cost effective to invest in end-use energy efficiency improvement than in increasing energy supply. In terms of electricity generation, the IPCC envisage that renewable energy can provide 30 to 35% of electricity by 2030 (up from 18% in 2005) at
505-686: A Changing Climate (SROCC) came out. The IPCC also updated its methodologies in 2019. So the sixth assessment cycle was the most ambitious in the IPCC's history. The predecessor of the IPCC was the Advisory Group on Greenhouse Gases (AGGG). Three organizations set up the AGGG in 1986. These were the International Council of Scientific Unions , the United Nations Environment Programme (UNEP), and
606-429: A change from pre-industrial conditions. Climate sensitivity is defined as the amount of global average surface warming following a doubling of carbon dioxide concentrations. It is likely to be in the range of 2 to 4.5 °C, with a best estimate of about 3 °C. This range of values is not a projection of the temperature rise we will see in the 21st century, since the future change in carbon dioxide concentrations
707-420: A contribution from each of the three working groups, plus a synthesis report. The synthesis report integrates the working group contributions. It also integrates any special reports produced in that assessment cycle. The IPCC does not carry out its own research. It does not monitor climate-related data. The reports by IPCC assess scientific papers and independent results from other scientific bodies. The IPCC sets
808-464: A deadline for publication of scientific papers that a report will cover. That report will not include new information that emerges after this deadline. However, there is a steady evolution of key findings and levels of scientific confidence from one assessment report to the next. Each IPCC report notes areas where the science has improved since the previous report. It also notes areas that would benefit from further research. The First Assessment Report
909-490: A full report divided into chapters. They also prepare a technical summary of the report, and a summary for policymakers . Each chapter has a number of authors to write and edit the material. A typical chapter has two coordinating lead authors, ten to fifteen lead authors and a larger number of contributing authors. The coordinating lead authors assemble the contributions of the other authors. They ensure that contributions meet stylistic and formatting requirements. They report to
1010-563: A large number of "default emission factors". These are factors to estimate the amount of emissions for an activity. The IPCC prepared this new version of the guidelines at the request of the UNFCCC. The UNFCCC accepted them for use at its 2013 Climate Change Conference , COP19, in Warsaw. The IPCC added further material in its 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories . AR4 Climate Change 2007 ,
1111-542: A lead author from the National Center for Atmospheric Research (NCAR). The original draft read: "However, adaptation alone is not expected to cope with all the projected effects of climate change, and especially not over the long run as most impacts increase in magnitude. Mitigation measures will therefore also be required. " The second sentence does not appear in the final version of the report. China objected to wording that said "based on observed evidence, there
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#17327661888131212-603: A number of academic studies of IPCC communications, for example in 2021. The IPCC archives its reports and electronic files on its website. They include the review comments on drafts of reports. The Environmental Science and Public Policy Archives in the Harvard Library also archives them. Between 1990 and 2023, the IPCC has published six comprehensive assessment reports reviewing the latest climate science. The IPCC has also produced 14 special reports on particular topics. Each assessment report has four parts. These are
1313-468: A range of views, expertise and geographical representation in its choice of authors. This ensures the author team includes experts from both developing and developed countries. The Bureau also seeks a balance between male and female authors. And it aims for a balance between those who have worked previously on IPCC reports and those new to the process. Scientists who work as authors on IPCC reports do not receive any compensation for this work, and all work on
1414-780: A reduction of average annual GDP growth rates of less than 0.12%. Stabilizing at 535 to 590 ppm would reduce average annual GDP growth rates by 0.1%, while stabilization at 590 to 710 ppm would reduce rates by 0.06%. There was high agreement and much evidence that a substantial fraction of these mitigation costs may be offset by benefits to health as a result of reduced air pollution, and that there would be further cost savings from other benefits such as increased energy security , increased agricultural production, and reduced pressure on natural ecosystems as well as, in certain countries, balance of trade improvements, provision of modern energy services to rural areas and employment. The IPCC considered that achieving these reductions would require
1515-495: A series of recommendations. The IPCC adopted many of them. One was to bring people with communications expertise into the Working Group Technical Support Units. Another was to consider communications questions early on in the preparation of reports. Following these steps in communications, the IPCC saw a significant increase in media coverage of its reports. This was particularly the case with
1616-415: A special report on climate change and cities during the seventh assessment cycle. The IPCC has a National Greenhouse Gas Inventories Programme. It develops methodologies and software for countries to report their greenhouse gas emissions. The IPCC's Task Force on National Greenhouse Gas Inventories (TFI) has managed the program since 1998. Japan's Institute for Global Environmental Strategies (IGES) hosts
1717-520: A very high confidence (about a 9 in 10 chance to be correct) WGII asserts that climate change is affecting terrestrial biological systems in that: WGII also states that the ocean has become more acidic because it has absorbed human-caused carbon dioxide. Ocean pH has dropped by 0.1, but how this affects marine life is not documented. WGII acknowledges some of the difficulties of attributing specific changes to human-caused global warming, stating that "Limitations and gaps prevent more complete attribution of
1818-419: A voluntary basis. They depend on the salaries they receive from their home institutions or other work. The work is labour-intensive with a big time commitment. It can disrupt participating scientists' research. This has led to concern that the IPCC process may discourage qualified scientists from participating. More than 3,000 authors (coordinating lead authors, lead authors, review editors) have participated in
1919-620: Is a formal nomination process by governments and observer organizations to find these experts. The IPCC has three working groups and a task force, which carry out its scientific work. The IPCC informs governments about the state of knowledge of climate change. It does this by examining all the relevant scientific literature on the subject. This includes the natural, economic and social impacts and risks . It also covers possible response options . The IPCC does not conduct its own original research. It aims to be objective and comprehensive. Thousands of scientists and other experts volunteer to review
2020-678: Is a good summary for the underlying report. This final review of the Summary of Policymakers takes place at sessions of the responsible working group or of the Panel. There are several types of endorsement which documents receive: The IPCC's most recent report is the Sixth Assessment Report (AR6) . The first three instalments of AR6 appeared in 2021 and 2022. The final synthesis report was completed in March 2023. The IPCC published
2121-425: Is affecting land. All three IPCC working groups and its Task Force on National Greenhouse Gas Inventories collaborated on the report. The report found that climate change is adding to the pressures we are putting on our land we use to live on and grow our food. It will only be possible to keep warming well below 2 °C if we reduce emissions from all sectors including land and food, it said. The Special Report on
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#17327661888132222-709: Is disrupting nature. The world faces unavoidable hazards over the next two decades even with global warming of 1.5 °C, it said. The IPCC published the Working Group III report, Climate Change 2022: Mitigation of Climate Change , in April 2022. It will be impossible to limit warming to 1.5 °C without immediate and deep cuts in greenhouse gas emissions. It is still possible to halve emissions by 2050, it said. The IPCC also publishes other types of reports. It produces Special Reports on topics proposed by governments or observer organizations. Between 1994 and 2019
2323-402: Is no longer up for debate." Kurt Volker , Principal Deputy Assistant Secretary for European and Eurasian Affairs, said, "We support the recent IPCC report, in which U.S. scientists played a leading role." Based on the report, 46 countries in a "Paris Call for Action" read out by French President Chirac , have called for the creation of a United Nations Environment Organization (UNEO), which
2424-562: Is possible at a reasonable cost, with stabilization between 445 ppm and 535 ppm costing less than 3% of global GDP . The WG III report analyses mitigation options for the main sectors in the near-term, addressing also cross-sectorial matters such as synergies, co-benefits, and trade-offs. It also provides information on long-term mitigation strategies for various stabilization levels, paying special attention to implications of different short-term strategies for achieving long-term goals. The Summary for Policymakers concludes that there
2525-479: Is projected with high confidence that: It is projected with high confidence that: It is projected with medium confidence (about 5 in 10 chance to be correct) that globally, potential food production will increase for temperature rises of 1–3 °C, but decrease for higher temperature ranges. It is projected with very high confidence that: US negotiators managed to eliminate language calling for cuts in greenhouse gas emissions, according to Patricia Romero Lankao,
2626-563: Is to have more power than the current United Nations Environment Programme (UNEP), and is to be modelled after the more powerful World Health Organization . The 46 countries included the European Union nations, but notably did not include the United States , China , Russia , and India , the top four emitters of greenhouse gases. Working Group II's Summary for Policymakers was released on 6 April 2007. The full report
2727-541: Is unknown, and factors besides carbon dioxide concentrations affect temperature. Model projections are made based on an analysis of various computer climate models running within the different scenarios that were established in 2000 in the Special Report on Emissions Scenarios (the "SRES scenarios"). As a result, predictions for the 21st century are as shown below. Scenario-specific projections are based on analysis of multiple runs by multiple climate models, using
2828-408: Is very high confidence that many natural systems, on all continents and in most oceans, are being affected by regional climate changes, particularly temperature increases". When China asked that the word "very" be stricken, three scientific authors balked, and the deadlock was broken only by a compromise to delete any reference to confidence levels. Working Group III's Summary for Policymakers (SPM)
2929-537: The Special Report on Global Warming of 1.5 °C in 2018 and Climate Change 2021: The Physical Science Basis , the Working Group I contribution to the Sixth Assessment Report , in 2021. There was also much greater public interest, reflected in the youth and other movements that emerged in 2018. IPCC reports are important for public awareness of climate change and related policymaking. This has led to
3030-573: The Fourth Assessment Report ( AR4 ) of the United Nations Intergovernmental Panel on Climate Change (IPCC), was published in 2007 and is the fourth in a series of reports intended to assess scientific, technical and socio-economic information concerning climate change , its potential effects, and options for adaptation and mitigation. The report is the largest and most detailed summary of
3131-573: The Fourth Report were asked to submit comments and observations in writing with the submissions analysed by the panel. Projections in AR5 are based on " Representative Concentration Pathways " (RCPs). The RCPs are consistent with a wide range of possible changes in future anthropogenic greenhouse gas emissions. Projected changes in global mean surface temperature and sea level are given in the main RCP article . The IPCC Fifth Assessment Report followed
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3232-654: The Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories and Good Practice Guidance for Land Use, Land-Use Change and Forestry . Parties to the UNFCCC and its Kyoto Protocol use the 1996 guidelines and two good practice reports for their annual submissions of inventories. The 2006 IPCC Guidelines for National Greenhouse Gas Inventories further update these methodologies. They include
3333-601: The UN Climate Change Conference in Paris during late 2015 . The report's Summary for Policymakers stated that warming of the climate system is 'unequivocal' with changes unprecedented over decades to millennia, including warming of the atmosphere and oceans, loss of snow and ice , and sea level rise . Greenhouse gas emissions, driven largely by economic and population growth, have led to greenhouse gas concentrations that are unprecedented in at least
3434-656: The World Meteorological Organization (WMO). The AGGG reviewed scientific research on greenhouse gases. It also studied increases in greenhouse gases. Climate science was becoming more complicated and covering more disciplines. This small group of scientists lacked the resources to cover climate science. The United States Environmental Protection Agency sought an international convention to restrict greenhouse gas emissions . The Reagan Administration worried that independent scientists would have too much influence. The WMO and UNEP therefore created
3535-412: The impacts of climate change and options for dealing with it. The IPCC does this by assessing peer-reviewed scientific literature. The United Nations endorsed the creation of the IPCC in 1988. The General Assembly resolution noted that human activity could change the climate. This could lead to severe economic and social consequences. It said increasing concentrations of greenhouse gases could warm
3636-707: The 13% share in 2008. In the scenarios with the highest shares for renewable energy, it contributes 77% by 2050. Later in 2011 the IPCC released the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX). This was a collaboration between Working Groups I and II. It was the first time two IPCC working groups worked together on a special report. The report shows how climate change has contributed to changes in extreme weather. And it show how policies to avoid and prepare for extreme weather events can reduce their impact. In
3737-542: The 195 UN Member states, who contribute "independently and voluntarily". In 2021, the countries giving the most money include the United States, Japan, France, Germany and Norway. Other countries, often developing ones, give an "in-kind contribution, by hosting IPCC meetings". In 2022, this budget was a little less than eight million euros. The IPCC bases its work on the decisions of the WMO and UNEP, which established
3838-515: The 48th Session of the Panel in Incheon, Republic of Korea. This took place in October 2018. They included 290 government officials and 60 representatives of observer organizations. The opening ceremonies of sessions of the Panel and of Lead Author Meetings are open to media. Otherwise, IPCC meetings are closed. The IPCC receives funding through a dedicated trust fund . UNEP and the WMO established
3939-673: The Fifth Assessment Report. For instance it made the approved report and press release available to registered media under embargo before the release. And it expanded its outreach activities with an outreach calendar. The IPCC held an Expert Meeting on Communication in February 2016, at the start of the Sixth Assessment Report cycle. Members of the old and new Bureaus worked with communications experts and practitioners at this meeting. This meeting produced
4040-481: The Fourth Assessment Report (AR4), participation from developing countries was increased, reflecting the ongoing efforts to improve regional coverage in the AR5. About 30% of authors came from developing countries or economies in transition. More than 60% of the experts chosen were new to the IPCC process, bringing fresh knowledge and perspectives. On 23 June 2010, the IPCC announced the release of
4141-585: The IPCC Fifth Assessment Report's sea-level rise projections . On 14 December 2012, drafts of the Working Group 1 (WG1) report were leaked and posted on the Internet. The release of the summary for policymakers occurred on 27 September 2013. Halldór Thorgeirsson, a UN official, warned that, because big companies are known to fund the undermining of climate science , scientists should be prepared for an increase in negative publicity at
IPCC Fifth Assessment Report - Misplaced Pages Continue
4242-436: The IPCC as an intergovernmental body in 1988. Scientists take part in the IPCC as both experts and government representatives. The IPCC produces reports backed by all leading relevant scientists. Member governments must also endorse the reports by consensus agreement. So the IPCC is both a scientific body and an organization of governments. Its job is to tell governments what scientists know about climate change. It also examines
4343-536: The IPCC began in 2023. In August 2021, the IPCC published its Working Group I contribution to the Sixth Assessment Report (IPCC AR6) on the physical science basis of climate change. The Guardian described this report as the "starkest warning yet" of "major inevitable and irreversible climate changes". Many newspapers around the world echoed this theme. In February 2022, the IPCC released its Working Group II report on impacts and adaptation. It published Working Group III's "mitigation of climate change" contribution to
4444-456: The IPCC in 1988. The United Nations endorsed the creation of the IPCC later that year. It has a secretariat in Geneva , Switzerland, hosted by the WMO. It has 195 member states who govern the IPCC. The member states elect a bureau of scientists to serve through an assessment cycle. A cycle is usually six to seven years. The bureau selects experts in their fields to prepare IPCC reports. There
4545-535: The IPCC published 14 special reports. Now usually more than one working group cooperates to produce a special report. The preparation and approval process is the same as for assessment reports. During the fifth assessment cycle the IPCC produced two special reports. It completed the Special Report on Renewable Energy Sources and Climate Change Mitigation (SRREN) in 2011. Working Group III prepared this report. The report examined options to use different types of renewable energy to replace fossil fuels. The report noted that
4646-475: The IPCC received approximately 3,000 author nominations from experts around the world. At the bureau session held in Geneva, 19–20 May 2010, the three working groups presented their selected authors and review editors for the AR5. Each of the selected scientists, specialists and experts was nominated in accordance with IPCC procedures, by respective national IPCC focal-points, by approved observer organizations, or by
4747-651: The IPCC. It also supports the work of the UNFCCC. The main work of the IPCC is to prepare assessment and other reports. It also supports other activities such as the Data Distribution Centre. This helps manage data related to IPCC reports. The IPCC has a "Gender Policy and Implementation Plan" to pay attention to gender in its work. It aims to carry out its work in an inclusive and respectful manner. The IPCC aims for balance in participation in IPCC work. This should offer all participants equal opportunity. The IPCC enhanced its communications activities for
4848-483: The Mom to the business leader, to the mayor to the head of state." US Secretary of State John Kerry responded to the report saying "This is yet another wakeup call: those who deny the science or choose excuses over action are playing with fire." Reporting on the publication of the report, The Guardian said that: In the end it all boils down to risk management. The stronger our efforts to reduce greenhouse gas emissions,
4949-533: The NY Times reported, had ended in disarray. Intergovernmental Panel on Climate Change The Intergovernmental Panel on Climate Change ( IPCC ) is an intergovernmental body of the United Nations . Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) set up
5050-517: The Ocean and Cryosphere in a Changing Climate (SROCC) examined how the ocean and frozen parts of the planet interact with climate change. (The cryosphere includes frozen systems such as ice sheets, glaciers and permafrost.) IPCC Working Groups I and II prepared the report. The report highlighted the need to tackle unprecedented changes in the ocean and cryosphere. It also showed how adaptation could help sustainable development . The IPCC will prepare
5151-485: The Sixth Assessment in April 2022. The Sixth Assessment Report concluded with a Synthesis Report in March 2023. During the period of the Sixth Assessment Report, the IPCC released three special reports. The first and most influential was the Special Report on Global Warming of 1.5°C in 2018. In 2019 the Special Report on Climate Change and Land (SRCCL), and the Special Report on the Ocean and Cryosphere in
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#17327661888135252-493: The Synthesis report include: Like previous assessment reports, it consists of four reports: Global warming projections from AR4 are shown below. The projections apply to the end of the 21st century (2090–2099), relative to temperatures at the end of the 20th century (1980–1999). Add 0.7 °C to projections to make them relative to pre-industrial levels instead of 1980–1999. (UK Royal Society, 2010, p=10 ). Descriptions of
5353-665: The TFI's Technical Support Unit. The IPCC approves its methodology reports at sessions of the Panel. The Panel adopts the Methodology Report's Overview Chapter by endorsing it section by section. The IPCC released its first Methodology Report, the IPCC Guidelines for National Greenhouse Gas Inventories , in 1994. The Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories updated this report. Two "good practice reports" complete these guidelines. These are
5454-478: The Working Group I report, Climate Change 2021: The Physical Science Basis , in August 2021. It confirms that the climate is already changing in every region. Many of these changes have not been seen in thousands of years. Many of them such as sea-level rise are irreversible over hundreds of thousands of years. Strong reductions in greenhouse gas emissions would limit climate change. But it could take 20–30 years for
5555-404: The Working Group co-chairs. Lead authors write sections of chapters. They invite contributing authors to prepare text, graphs or data for inclusion. Review editors must ensure that authors respond to comments received during the two stages of drafts review: the first is only open to external experts and researchers, while the second is also open to government representatives. The Bureau aims for
5656-488: The bureau. The IPCC received 50% more nominations of experts to participate in AR5 than it did for AR4 . A total of 559 authors and review editors had been selected for AR4 from 2,000 proposed nominees. On 23 June 2010 the IPCC announced the release of the final list of selected coordinating lead authors, comprising 831 experts who were drawn from fields including meteorology , physics, oceanography, statistics, engineering, ecology, social sciences and economics. In comparison to
5757-451: The causes of observed system responses to anthropogenic warming." but found that the agreement between observed and projected changes was "Nevertheless ... sufficient to conclude with high confidence that anthropogenic warming over the last three decades has had a discernible influence on many physical and biological systems." WGII describes some of what might be expected in the coming century, based on studies and model projections. It
5858-548: The climate change situation ever undertaken, produced by thousands of authors, editors, and reviewers from dozens of countries, citing over 6,000 peer-reviewed scientific studies. People from over 130 countries contributed to the IPCC Fourth Assessment Report, which took six years to produce. Contributors to AR4 included more than 2,500 scientific expert reviewers, more than 800 contributing authors, and more than 450 lead authors. "Robust findings" of
5959-472: The climate to stabilize. This report attracted enormous media and public attention. U.N. Secretary-General António Guterres described it as "code red for humanity". The IPCC published the Working Group II report, Climate Change 2022: Impacts, Adaptation and Vulnerability , in February 2022. Climate change due to human activities is already affecting the lives of billions of people, it said. It
6060-419: The cost of most renewables technologies had fallen. It was likely to fall even more with further advances in technology. It said renewables could increase access to energy. The report reviewed 164 scenarios that examine how renewables could help stop climate change. In more than half of these scenarios, renewables would contribute more than 27% of primary energy supply in mid-century. This would be more than double
6161-400: The course of six assessments the reports reflect the growing evidence for a changing climate. And they show how this is due to human activity. The IPCC has adopted its rules of procedure in the "Principles Governing IPCC Work". These state that the IPCC will assess: Under IPCC rules its assessments are comprehensive, objective, open and transparent. They cover all the information relevant to
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#17327661888136262-435: The drafting of IPCC reports since its creation. Expert reviewers comment at different stages on the drafts. Reviewers come from member governments and IPCC observers. Also, anyone may become an IPCC reviewer by stating they have the relevant expertise. There are generally three stages in the review process. First comes expert review of the first draft of the chapters. The next stage is a review by governments and experts of
6363-553: The election of the new IPCC Bureau. His predecessor was Korean economist Hoesung Lee , elected in 2015. The previous chairs were Rajendra K. Pachauri , elected in 2002, Robert Watson , elected in 1997, and Bert Bolin , elected in 1988. The Panel consists of representatives appointed by governments. They take part in plenary sessions of the IPCC and its Working Groups. Non-governmental and intergovernmental organizations may attend as observers. Meetings of IPCC bodies are by invitation only. About 500 people from 130 countries attended
6464-473: The final list of selected coordinating lead authors, comprising 831 experts. The working group reports would be published during 2013 and 2014. These experts would also provide contributions to the Synthesis Report published in late 2014. The Fifth Assessment Report ( Climate Change 2013 ) would be released in four distinct sections: The full text of Climate Change 2013: The Physical Science Basis
6565-451: The fund in 1989. The trust fund receives annual financial contributions from member governments. The WMO, UNEP and other organizations also contribute. Payments are voluntary and there is no set amount required. The WMO covers the operating costs of the secretariat. It also sets the IPCC's financial regulations and rules. The Panel sets the annual budget. In 2021, the IPCC's annual budget amounts to approximately six million euros, financed by
6666-484: The greenhouse gas emissions scenarios can be found in Special Report on Emissions Scenarios . "Likely" means greater than 66% probability of being correct, based on expert judgement. The report was released in four principal sections: The full WGI report was published in March 2007, and last updated in September of that year. It includes a Summary for Policymakers (SPM), which was published in February 2007, and
6767-441: The key debates concerned a proposal to limit concentrations of greenhouse gases in the atmosphere to between 445 parts per million and 650 parts per million to avoid dangerous climate change , with pressure from developing countries to raise the lower limit. Despite this, the figures from the original proposal were incorporated into the Summary for Policymakers. The Summary concludes that stabilization of greenhouse gas concentrations
6868-466: The kinds of harm already being experienced from climate change will continue to worsen unless and until comprehensive and vigorous action to reduce emissions is undertaken worldwide." It went on to say that Ban Ki-moon , the United Nations secretary general, had declared his intention to call a meeting of heads of state in 2014 to develop such a treaty. The last such meeting, in Copenhagen in 2009 ,
6969-435: The last 800,000 years. These, together with other anthropogenic drivers, are "extremely likely" (where that means more than 95% probability) to have been the dominant cause of the observed global warming since the mid-20th century. Conclusions of the fifth assessment report are summarized below: The Fifth Assessment Report (AR5) consists of three Working Group (WG) Reports and a Synthesis Report. The first Working Group Report
7070-570: The likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks. The IPCC was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess scientific , technical and socio-economic information concerning climate change , its potential effects and options for adaptation and mitigation. In March 2010,
7171-419: The lower the risk of extreme climate impacts. The higher our emissions, the larger climate changes we'll face, which also means more expensive adaptation, more species extinctions, more food and water insecurities, more income losses, more conflicts, and so forth. The New York Times reported that: In Washington, President Obama's science adviser, John P. Holdren , cited increased scientific confidence "that
7272-537: The media regularly quote from its reports. IPCC reports play a key role in the annual climate negotiations held by the United Nations Framework Convention on Climate Change (UNFCCC). The IPCC Fifth Assessment Report was an important influence on the landmark Paris Agreement in 2015. The IPCC shared the 2007 Nobel Peace Prize with Al Gore for contributions to the understanding of climate change. The seventh assessment cycle of
7373-460: The paralysis of fear. We need both to reduce our emissions of greenhouse gases and to prepare for the impacts of climate change. Those who would claim otherwise can no longer use science as a basis for their argument." U.S. Energy Secretary Samuel Bodman told a news conference that the report was "sound science" and "As the president has said, and this report makes clear, human activity is contributing to changes in our earth's climate and that issue
7474-540: The planet . This would cause the sea level to rise . The effects for humanity would be disastrous if timely steps were not taken. The IPCC does not conduct original research. It produces comprehensive assessments on the state of knowledge of climate change. It prepares reports on special topics relevant to climate change. It also produces methodologies. These methodologies help countries estimate their greenhouse gas emissions and removals through sinks. Its assessments build on previous reports and scientific publications. Over
7575-553: The planet in terms of radiative forcing —the rate of change of energy in the system, measured as power per unit area (in SI units, W/m ). The report shows in detail the individual warming contributions (positive forcing) of carbon dioxide, methane, nitrous oxide, halocarbons , other human warming factors, and the warming effects of changes in solar activity. Also shown are the cooling effects (negative forcing) of aerosols , land-use changes, and other human activities. All values are shown as
7676-661: The private sector and experts from NGOs. The IPCC Bureau or Working Group Bureau selects the authors of the reports from government nominations. Lead authors of IPCC reports assess the available information about climate change based on published sources. According to IPCC guidelines, authors should give priority to peer-reviewed sources. Authors may refer to non-peer-reviewed sources ("grey literature"), if they are of sufficient quality. These could include reports from government agencies and non-governmental organizations. Industry journals and model results are other examples of non-peer-reviewed sources. Authors prepare drafts of
7777-439: The public. It put the 1.5 °C target at the centre of climate activism . In 2019 the IPCC released two more special reports that examine different parts of the climate system. The Special Report on Climate Change and Land (SRCCL) examined how the way we use land affects the climate. It looked at emissions from activities such as farming and forestry rather than from energy and transport. It also looked at how climate change
7878-424: The publications. They compile key findings into "Assessment Reports" for policymakers and the general public; Experts have described this work as the biggest peer review process in the scientific community. Leading climate scientists and all member governments endorse the IPCC's findings. This underscores that the IPCC is a well-respected authority on climate change. Governments, civil society organizations and
7979-445: The relevant working group, with the help of its technical support unit) uses these lists as a basis for appointing authors, while retaining the possibility of appointing people who are not on the list, primarily on the basis of scientific excellence and diversity of viewpoints, and to a lesser extent by ensuring geographical diversity, experience within the IPCC and gender. Authors may include, in addition to researchers, personalities from
8080-435: The report's projections of sea-level change, which in the new report was estimated at less than previous estimates. The now-published text gives a warning that the new estimation of sea-level could be too low: "Dynamical processes related to ice flow not included in current models but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea level rise." The mid-points of
8181-412: The report. Lead authors' meetings and a number of workshops and expert meetings, in support of the assessment process, were held. A schedule of AR5 related meetings, review periods, and other important dates was published. A key statement of the report was that: Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system , increasing
8282-423: The revised draft of the chapters and the first draft of the Summary for Policymakers. The third stage is a government review of the revised Summary for Policymakers. Review comments and author responses remain in an open archive for at least five years. Finally government representatives together with the authors review the Summary for Policymakers. They go through the Summary for Policymakers line by line to ensure it
8383-429: The same general format as the Fourth Assessment Report, with three Working Group reports and a Synthesis report. The report was delivered in stages, starting with the report from Working Group I in September 2013. It reported on the physical science basis, based on 9,200 peer-reviewed studies. The Synthesis Report was released on 2 November 2014, in time to pave the way for negotiations on reducing carbon emissions at
8484-473: The same way policies to respond to events and recover from them can make societies more resilient. During the sixth assessment cycle the IPCC produced three special reports. This made it the most ambitious cycle in IPCC history. The UNFCCC set a goal of keeping global warming well below 2 °C while trying to hold it at 1.5 °C, when it reached the Paris Agreement at COP21 in 2015. But at
8585-704: The scenarios from the Special Report on Emissions Scenarios the models are performing simulations for various Representative Concentration Pathways . AR5 relies on the Coupled Model Intercomparison Project Phase 5 (CMIP5), an international effort among the climate modeling community to coordinate climate change experiments. Most of the CMIP5 and Earth System Model (ESM) simulations for AR5 WRI were performed with prescribed CO 2 concentrations reaching 421 ppm ( RCP 2.6), 538 ppm (RCP4.5), 670 ppm (RCP6.0), and 936 ppm (RCP 8.5) by
8686-563: The scientific understanding of climate change. This draws on scientific, technical and socioeconomic information. IPCC reports must be neutral regarding policy recommendations. However, they may address the objective factors relevant to enacting policies. The IPCC has the following structure: The chair of the IPCC is British energy scientist Jim Skea , who is hosted by the International Institute for Environment and Development (IIED). Skea has served since 28 July 2023 with
8787-634: The sea level rise estimates are within ±10% of those from the TAR ; but the range has narrowed. Lord Rees , the president of the Royal Society , said, "This report makes it clear, more convincingly than ever before, that human actions are writ large on the changes we are seeing, and will see, to our climate. The IPCC strongly emphasises that substantial climate change is inevitable, and we will have to adapt to this. This should compel all of us—world leaders, businesses and individuals—towards action rather than
8888-1124: The summary was reviewed line by line by representatives of 113 governments during the 10th session of WGI, in January to February 2007. On the issue of global warming and its causes, the SPM states that: Very likely and likely mean "the assessed likelihood, using expert judgment" are over 90% and over 66%, respectively. The report notes many observed changes in the Earth's climate including atmospheric composition, global average temperatures, ocean conditions, and other climate changes. Carbon dioxide , methane , and nitrous oxide are all long-lived greenhouse gases . Cold days, cold nights, and frost events have become less frequent. Hot days, hot nights, and heat waves have become more frequent. Additionally: The SPM documents increases in wind intensity, decline of permafrost coverage, and increases of both drought and heavy precipitation events. Additionally: Table SPM-2 lists recent trends along with certainty levels for
8989-470: The time there was little understanding of what warming of 1.5 °C meant. There was little scientific research explaining how the impacts of 1.5 °C would differ from 2 °C. And there was little understanding about how to keep warming to 1.5 °C. So the UNFCCC invited the IPCC to prepare a report on global warming of 1.5 °C. The IPCC subsequently released the Special Report on Global Warming of 1.5 °C (SR15) in 2018. The report showed that it
9090-627: The time. "Vested interests are paying for the discrediting of scientists all the time. We need to be ready for that," he said. Marking the finalization of the Physical Science Basis UN Secretary General Ban Ki-moon addressed the IPCC at Stockholm on 27 September 2013. He stated that "the heat is on. We must act". Jennifer Morgan, from the World Resources Institute , said "Hopefully the IPCC will inspire leadership, from
9191-495: The trend having actually occurred, for a human contribution to the trend, and for the trend occurring in the future. In relation to changes (including increased hurricane intensity) where the certainty of a human contribution is stated as "more likely than not" footnote f to table SPM-2 notes "Magnitude of anthropogenic contributions not assessed. Attribution for these phenomena based on expert judgment rather than formal attribution studies." AR4 describes warming and cooling effects on
9292-431: The various SRES Scenarios. "Low scenario" refers to B1, the most optimistic scenario family. "High scenario" refers to A1FI, the most pessimistic scenario family. There are six families of SRES scenarios, and AR4 provides projected temperature and sea level rises (excluding future rapid dynamical changes in ice flow) for each scenario family. In the weeks before publication of the first report, controversy broke out about
9393-612: The year 2100. (IPCC AR5 WGI, page 22). The summary also detailed the range of forecasts for warming, and climate impacts with different emission scenarios. Compared to the previous report, the lower bounds for the sensitivity of the climate system to emissions were slightly lowered, though the projections for global mean temperature rise (compared to pre-industrial levels) by 2100 exceeded 1.5 °C in all scenarios. In August 2020 scientists reported that observed ice-sheet losses in Greenland and Antarctica track worst-case scenarios of
9494-570: Was a high level of agreement and much evidence that "there is substantial economic potential for the mitigation of global greenhouse gas emissions over the coming decades, that could offset the projected growth of global emissions or reduce emissions below current levels", taking into account financial and social costs and benefits. The technologies with the largest economic potential within this timescale are considered to be: The IPCC estimates that stabilizing atmospheric greenhouse gases at between 445–535 ppm CO 2 equivalent would result in
9595-403: Was possible to keep warming below 1.5 °C during the 21st century. But this would mean deep cuts in emissions. It would also mean rapid, far-reaching changes in all aspects of society. The report showed warming of 2 °C would have much more severe impacts than 1.5 °C. In other words: every bit of warming matters. SR15 had an unprecedented impact for an IPCC report in the media and with
9696-519: Was published in 1990 and received an update in 1992. In intervals of about six years, new editions of IPCC Assessment Report followed. The focal points of the Member states — the individual appointed by each state to liaise with the IPCC — and the observer organizations submit to the IPCC Bureau a list of personalities, which they have freely constituted. The Bureau (more precisely, the co-chairs of
9797-535: Was published in 2013 and the rest were completed in 2014. The summaries for policy makers were released on 27 September 2013 for the first report, on 31 March 2014 for the second report entitled "Impacts, Adaptation, and Vulnerability", and on 14 April 2014 for the third report entitled "Mitigation of Climate Change". The AR5 provides an update of knowledge on the scientific , technical and socio-economic aspects of climate change . More than 800 authors, selected from around 3,000 nominations, were involved in writing
9898-465: Was published on 4 May 2007 at the 26th session of the IPCC. The full WG III report was published online in September 2007. The IPCC convened in Bangkok on April 30 to start discussions on the draft Summary, with the participation of over 400 scientists and experts from about 120 countries. At the full IPCC meeting on May 4, agreement was reached by the larger gathering of some 2,000 delegates. One of
9999-429: Was rated on a confidence scale, qualitatively from very low to very high and, where possible, quantitatively from exceptionally unlikely to virtually certain (determined based on statistical analysis and expert judgement). The principal findings were: Climate model simulations in support of AR5 use a different approach to account for increasing greenhouse gas concentrations than in the previous report. Instead of
10100-433: Was released 18 September 2007. WGII states that "evidence from all continents and most oceans shows that many natural systems are being affected by regional climate changes, particularly temperature increases". Some observed changes have been associated with climate change at varying levels of confidence. With a high confidence (about an 8 in 10 chance to be correct) WGII asserts that climate change has resulted in: With
10201-489: Was released in an unedited form on Monday, 30 September 2013. It was over 2,000 pages long and cited 9,200 scientific publications. The full, edited report was released online in January 2014 and published in physical form by Cambridge University Press later in the year. A concise overview of Working Group I's findings was published as the Summary for Policymakers on 27 September 2013. The level of confidence in each finding
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