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The Fifth Assessment Report (AR5) of the United Nations
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) a ...
(IPCC) is the fifth in
a series of such reports and was completed in 2014.
[IPCC (2014]
The IPCC’s Fifth Assessment Report (AR5) leaflet
/ref> 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 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
A Representative Concentration Pathway (RCP) is a greenhouse gas concentration (not emissions) trajectory adopted by the IPCC. Four pathways were used for climate modeling and research for the IPCC fifth Assessment Report (AR5) in 2014. The pa ...
" (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.
AR5 followed the same general format as of AR4, with three Working Group reports and a Synthesis report. The report was delivered in stages, starting with the report from Working GroupI in September 2013 which 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 the UN Climate Change Conference in Paris during late 2015.
Conclusions of the fifth assessment report are summarized below:
* Working Group I: "Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia". "Atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years". Human influence on the climate system is clear.[
IPCC (11 November 2013): D. Understanding the Climate System and its Recent Changes, in]
Summary for Policymakers
in:
It is extremely likely (95–100% probability) that human influence was the dominant cause of global warming between 1951 and 2010.
* Working Group II: "Increasing magnitudes of lobalwarming increase the likelihood of severe, pervasive, and irreversible impacts".[IPCC (25 June 2014): B-1. Key risks across Sectors and Regions, in]
Summary for Policymakers
in: "A first step towards adaptation to future climate change is reducing vulnerability and exposure to present climate variability". "The overall risks of climate change impacts can be reduced by limiting the rate and magnitude of climate change"
* Working Group III: Without new policies to mitigate climate change, projections suggest an increase in global mean temperature in 2100 of 3.7 to 4.8 °C, relative to pre-industrial levels (median values; the range is 2.5 to 7.8 °C including climate uncertainty). "(T)he current trajectory of global annual and cumulative emissions of GHGs is not consistent with widely discussed goals of limiting global warming at 1.5 to 2 degrees Celsius above the pre-industrial level." Pledges made as part of the Cancún Agreements are broadly consistent with cost-effective scenarios that give a "likely" chance (66–100% probability) of limiting global warming (in 2100) to below 3 °C, relative to pre-industrial levels.
Current status
The Fifth Assessment Report (AR5) consists of three Working Group (WG) Reports and a Synthesis Report. The first Working Group Report was published in 2013 and the rest were completed in 2014. The summaries for policy
Policy is a deliberate system of guidelines to guide decisions and achieve rational outcomes. A policy is a statement of intent and is implemented as a procedure or protocol. Policies are generally adopted by a governance body within an organ ...
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".
*WG I: The Physical Science Basis – 30 September 2013, Summary for Policymakers
The Summary for policymakers (SPM)
is a summary of the Intergovernmental Panel on Climate Change (IPCC) reports intended to aid policymakers. The form is approved line by line by governments: "Negotiations occur over wording to ensure accuracy, ...
published 27 September 2013.
*WG II: Impacts, Adaptation and Vulnerability – 31 March 2014
*WG III: Mitigation of Climate Change – 15 April 2014
*AR5 Synthesis Report (SYR) – 2 November 2014
The AR5 provides an update of knowledge on the scientific
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earliest archeological evidence for ...
, technical and socio-economic
Socioeconomics (also known as social economics) is the social science that studies how economic activity affects and is shaped by social processes. In general it analyzes how modern societies progress, stagnate, or regress because of their local ...
aspects of climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
.
More than 800 authors, selected from around 3,000 nominations, were involved in writing 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.
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 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
Ban Ki-moon (; ; born 13 June 1944) is a South Korean politician and diplomat who served as the eighth secretary-general of the United Nations between 2007 and 2016. Prior to his appointment as secretary-general, Ban was his country's Minister ...
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
The World Resources Institute (WRI) is a global research non-profit organization established in 1982 with funding from the MacArthur Foundation under the leadership of James Gustave Speth. WRI's activities are focused on seven areas: food, fore ...
, said "Hopefully the IPCC will inspire leadership, from the Mom to the business leader, to the mayor to the head of state." US Secretary of State John Kerry
John Forbes Kerry (born December 11, 1943) is an American attorney, politician and diplomat who currently serves as the first United States special presidential envoy for climate. A member of the Forbes family and the Democratic Party (Unite ...
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."
Authors and editors
The IPCC was established in 1988 by the World Meteorological Organization
The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics.
The WMO originated from the Internati ...
(WMO) and the United Nations Environment Programme
The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on th ...
(UNEP) to assess scientific
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earliest archeological evidence for ...
, technical and socio-economic
Socioeconomics (also known as social economics) is the social science that studies how economic activity affects and is shaped by social processes. In general it analyzes how modern societies progress, stagnate, or regress because of their local ...
information concerning climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, its potential effects and options for adaptation and mitigation.
In March 2010, 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 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
Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not ...
, physics, oceanography, statistics, engineering, ecology, social sciences and economics. In comparison to 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.
Climate change 2013: report overview
On 23 June 2010, the IPCC announced the release of 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:
* Working Group I Report (WGI): Focusing on the physical science basis and including 258 experts.
* Working Group II Report (WGII): Assessing the impacts, adaptation strategies and vulnerability related to climate change and involving 302 experts.
* Working Group III Report (WGIII): Covering mitigation response strategies in an integrated risk and uncertainty framework and its assessments carried out by 271 experts.
* The Synthesis Report (SYR): Final summary and overview.
Working group I contribution
The full text of ''Climate Change 2013: The Physical Science Basis'' 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
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press
A university press is an academic publishing hou ...
later in the year.
Summary for Policymakers
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 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:[
]
=General
=
* Warming of the atmosphere and ocean system is ''unequivocal''. Many of the associated impacts such as sea level change (among other metrics) have occurred since 1950 at rates unprecedented in the historical record.
* There is a clear human influence on the climate
* It is ''extremely likely'' that human influence has been the dominant cause of observed warming since 1950, with the level of confidence having increased since the fourth report.
* IPCC pointed out that the longer we wait to reduce our emissions, the more expensive it will become.
=Historical climate metrics
=
* It is ''likely'' (with medium confidence) that 1983–2013 was the warmest 30-year period for 1,400 years.
* It is ''virtually certain'' the upper ocean warmed from 1971 to 2010. This ocean warming accounts, with ''high confidence'', for 90% of the energy accumulation between 1971 and 2010.
* It can be said with ''high confidence'' that the Greenland
Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
and Antarctic
The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...
ice sheets have been losing mass in the last two decades and that Arctic sea ice
The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September, then increases during fall ...
and Northern Hemisphere spring snow cover have continued to decrease in extent.
* There is ''high confidence'' that the sea level rise since the middle of the 19th century has been larger than the mean sea level rise of the prior two millennia.
* Concentration of greenhouse gas
A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
es in the atmosphere has increased to levels unprecedented on earth in 800,000 years.
* Total radiative forcing
Radiative forcing (or climate forcing) is the change in energy flux in the atmosphere caused by natural or anthropogenic factors of climate change as measured by watts / metre2. It is a scientific concept used to quantify and compare the external ...
of the earth system, relative to 1750, is positive and the most significant driver is the increase in 's atmospheric concentration.
=Models
=
AR5 relies on the Coupled Model Intercomparison Project Phase 5 (CMIP5), an international effort among the climate modeling
Numerical climate models use quantitative methods to simulate the interactions of the important drivers of climate, including atmosphere, oceans, land surface and ice. They are used for a variety of purposes from study of the dynamics of the ...
community to coordinate climate change experiments. Most of the CMIP5 and Earth System Model (ESM) simulations for AR5 WRI were performed with prescribed concentrations reaching 421 ppm ( RCP2.6), 538 ppm (RCP4.5), 670 ppm (RCP6.0), and 936 ppm (RCP 8.5) by the year 2100. (IPCC AR5 WGI, page 22).
* Climate models have improved since the prior report.
* Model results, along with observations, provide confidence in the magnitude of global warming in response to past and future forcing.
=Projections
=
* Further warming will continue if emissions of greenhouse gases continue.
* The global surface temperature increase by the end of the 21st century is ''likely'' to exceed 1.5 °C relative to the 1850 to 1900 period for most scenarios, and is ''likely'' to exceed 2.0 °C for many scenarios
* The global water cycle
The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly cons ...
will change, with increases in disparity between wet and dry regions, as well as wet and dry seasons, with some regional exceptions.
* The oceans will continue to warm, with heat extending to the deep ocean, affecting circulation patterns.
* Decreases are ''very likely'' in Arctic sea ice cover, Northern Hemisphere spring snow cover, and global glacier volume
* Global mean sea level will continue to rise at a rate ''very likely'' to exceed the rate of the past four decades
* Changes in climate will cause an increase in the rate of production. Increased uptake by the oceans will increase the acidification of the oceans.
* Future surface temperatures will be largely determined by cumulative , which means climate change will continue even if emissions are stopped.
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
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
track worst-case scenarios of the IPCC Fifth Assessment Report's sea-level rise
Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cryo ...
projections.
Other
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 the scenarios from the Special Report on Emissions Scenarios
The Special Report on Emissions Scenarios (SRES) is a report by the Intergovernmental Panel on Climate Change (IPCC) that was published in 2000. The climate change scenario, greenhouse gas emissions scenarios described in the Report have been u ...
the models are performing simulations for various Representative Concentration Pathways
A Representative Concentration Pathway (RCP) is a greenhouse gas concentration (not emissions) trajectory adopted by the IPCC. Four pathways were used for climate modeling and research for the IPCC fifth Assessment Report (AR5) in 2014. The pa ...
.
Public debate after the publication of AR4 in 2009 put the IPCC under scrutiny, with controversies over alleged bias and inaccuracy in its reports. In 2010, this prompted U.N. Secretary-General Ban Ki-moon
Ban Ki-moon (; ; born 13 June 1944) is a South Korean politician and diplomat who served as the eighth secretary-general of the United Nations between 2007 and 2016. Prior to his appointment as secretary-general, Ban was his country's Minister ...
and IPCC chair Rajendra K. Pachauri
Rajendra Kumar Pachauri (20 August 1940 – 13 February 2020) was the chairman of the Intergovernmental Panel on Climate Change (IPCC) from 2002 to 2015, during the fourth and fifth assessment cycles. Under his leadership the IPCC was awarded ...
to request that the InterAcademy Council (IAC) review the IPCC and recommend ways to strengthen its processes and procedures for the preparation of AR5. The IAC report made recommendations to fortify IPCC's management structure, to further develop its conflict-of-interest policy, to strengthen the review process, to clarify the guidelines on the use of so-called gray literature
Grey literature (or gray literature) is materials and research produced by organizations outside of the traditional commercial or academic publishing and distribution channels. Common grey literature publication types include reports (annual, rese ...
, to ensure consistency in the use of probabilities for the likelihood of outcomes, and to improve its communications strategy especially regarding transparency and rapidity of response.
Condensed versions
The Climate and Development Knowledge Network
The Climate and Development Knowledge Network (CDKN) works to enhance the quality of life for the poorest and most vulnerable to climate change. CDKN does this by combining research, advisory services and knowledge management in support of local ...
has produced region-specific toolkits for policy makers, practitioners, journalists and teachers based on the findings in the Fifth Assessment Report. They include summary reports which distill the key findings of the IPCC report; as well as media materials such as infographics, slideshow presentations and images which can be used for training, educational and reporting purposes. The four toolkits that have been developed are:
The IPCC's Fifth Assessment Report: What's in it for Small Islands Developing States?
The IPCC's Fifth Assessment Report: What's in it for South Asia?
The IPCC's Fifth Assessment Report: What's in it for Africa?
The IPCC's Fifth Assessment Report: What's in it for Latin America?
Special Report on Global Warming of 1.5 °C
The IPCC published their "Special Report on Global Warming of 1.5 °C" on 8 October 2018.
See also
* ''Renewable Energy Sources and Climate Change Mitigation
The United Nations Intergovernmental Panel on Climate Change (IPCC) published a special report on ''Renewable Energy Sources and Climate Change Mitigation'' (''SRREN'') on May 9, 2011. The report developed under the leadership of Ottmar Edenhofer ...
'' – IPCC special report, 2011
* IPCC Sixth Assessment Report
The Sixth Assessment Report (AR6) of the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC) is the sixth in a series of reports which assess scientific, technical, and socio-economic information concerning climate change. Three ...
References
Sources
* . Archived
* . Archived
*
Climate Change 2013 Working Group 1 website.
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External links
Official IPCC WGI AR5 website
{{DEFAULTSORT:Ipcc Fifth Assessment Report
2014 in science
2014 in the environment
Articles containing video clips
Climate change assessment and attribution
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