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{{Short description|Evaluation of climate change by the scientific community}}
National and international science academies and professional societies have assessed the current '''scientific opinion on climate change''', in particular recent ]. These assessments have largely followed or endorsed the ] position that ''"An increasing body of observations gives a collective picture of a warming world and other changes in the climate system... There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities''."<ref name = "IPCC WG1">, IPCC.</ref>
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] from various scientific organizations show substantial agreement concerning the progress and extent of global warming: pairwise correlations for long-term datasets (1850+ and 1880+) exceed ].]]
This page documents ] as given by synthesis reports, scientific bodies of national or international standing, and surveys of opinion among climate scientists. It does not document the views of individual scientists or ] lists of individuals such as petitions.
There is a nearly unanimous<!--File:20200324 Global average temperature - NASA-GISS HadCrut NOAA Japan BerkeleyE.svg and File:20211103 Academic studies of scientific consensus - global warming, climate change - vertical bar chart - en.svg--> ] that the ] since the start of the ], that the rate of recent warming is largely unprecedented,<ref name="IPCC_AR6_WGI_SPM" />{{rp|8}}<ref name="NCAR5_Ch2" />{{rp|11}} and that this warming is mainly the result of a rapid increase in atmospheric ] caused by human activities. The human activities causing this warming include ], ], and ] changes such as ],<ref>"Total radiative forcing is positive and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO<sub>2</sub> since 1750." and "From 1750 to 2011, CO<sub>2</sub> emissions from fossil fuel combustion and cement production have released 375 GtC to the atmosphere, while deforestation and other land-use change are estimated to have released 180 GtC." In: . Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.</ref>{{rp|10–11}} with a significant supporting role from the other ]es such as ] and ].<ref name="IPCC_AR6_WGI_SPM" />{{rp|7}} This human role in climate change is considered "unequivocal" and "incontrovertible".<ref name="IPCC_AR6_WGI_SPM" />{{rp|4}}<ref name="NCAR5_Ch2" />{{rp|4}}


Nearly all actively publishing ] say humans are causing climate change.<ref name="Myers_2021" /><ref>{{cite journal|author=John Cook|display-authors= etal| title= Consensus on consensus: a synthesis of consensus estimates on human-caused global warming| journal= Environmental Research Letters |date=April 2016| doi=10.1088/1748-9326/11/4/048002|volume=11|issue=4|pages=048002|bibcode=2016ERL....11d8002C|doi-access=free}}</ref> Surveys of the scientific literature are another way to measure scientific consensus. A 2019 review of scientific papers found the consensus on the cause of climate change to be at 100%,<ref name="Powell2019" /> and a 2021 study concluded that over 99% of scientific papers agree on the human cause of climate change.<ref name="EnvRschLtrs_20211019" /> The small percentage of papers that disagreed with the consensus often contained errors or could not be replicated.<ref>{{Cite journal |last1=Benestad| first1=Rasmus E.|last2= Nuccitelli| first2= Dana|last3= Lewandowsky| first3= Stephan |last4=Hayhoe| first4= Katharine|last5=Hygen|first5=Hans Olav|last6=van Dorland| first6= Rob| last7=Cook|first7=John|date=1 November 2016|title=Learning from mistakes in climate research |journal= Theoretical and Applied Climatology |language=en|volume=126|issue=3|pages=699–703 |bibcode= 2016ThApC.126..699B|doi=10.1007/s00704-015-1597-5|issn=1434-4483 |doi-access=free}}</ref>
{{EnergyPortal}}
==Statements by concurring organizations==


The evidence for global warming due to human influence has been recognized by the national science academies of all the major industrialized countries.<ref>{{cite web |year=2005 |title=Joint Science Academies' Statement |url=http://nationalacademies.org/onpi/06072005.pdf |url-status=dead |archive-url=https://web.archive.org/web/20130909022954/http://www.nationalacademies.org/onpi/06072005.pdf |archive-date=2013-09-09 |access-date=2014-04-20 |quote=It is likely that most of the warming in recent decades can be attributed to human activities (IPCC 2001). This warming has already led to changes in the Earth's climate.}}</ref> In the ], there is a very strong consensus that global surface temperatures have increased in recent decades and that the trend is caused by human-induced emissions of ]es.<ref>{{Cite web |title='Climate Change 2013: The Physical Science Basis.' IPCC Fifth Assessment Report, Working Group I, Summary for Policymakers. 'The best estimate of the human-induced contribution to warming is similar to the observed warming over this period.' |url=https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WGIAR5_SPM_brochure_en.pdf |url-status=dead |archive-url=https://web.archive.org/web/20181022184656/https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WGIAR5_SPM_brochure_en.pdf |archive-date=22 October 2018 |access-date=26 December 2018}}</ref> No scientific body of national or international standing disagrees with this view.<ref>{{cite journal |author=Julie Brigham-Grette |author2=<Please add first missing authors to populate metadata.> |last3=Clague |last4=Cole |last5=Doran |last6=Gillespie |last7=Grimm |last8=Guccione |last9=Hughen |last10=Jackson |last11=Jull |last12=Leavitt |last13=Mandel |last14=Ortiz |last15=Rodbell |display-authors=1 |date=September 2006 |title=Petroleum Geologists' Award to Novelist Crichton Is Inappropriate |journal=] |volume=87 |issue=36 |pages=364 |bibcode=2006EOSTr..87..364B |doi=10.1029/2006EO360008 |quote=The AAPG stands alone among scientific societies in its denial of human-induced effects on global warming. |doi-access=free |last16=Schweger |last17=Smith |last18=Styles}}</ref> A few organizations with members in ] hold ],<ref>{{cite book |last1=DiMento |first1=Joseph F. C. |url=https://archive.org/details/climatechangewha00dime/page/68 |title=Climate Change: What It Means for Us, Our Children, and Our Grandchildren |last2=Doughman |first2=Pamela M. |publisher=The MIT Press |year=2007 |isbn=978-0-262-54193-0 |page=}}</ref> and some have tried to persuade the public that climate change is not happening, or if the climate is changing it is not because of human influence,<ref>{{cite journal |last1=Stoddard |first1=Isak |last2=Anderson |first2=Kevin |last3=Capstick |first3=Stuart |last4=Carton |first4=Wim |last5=Depledge |first5=Joanna |last6=Facer |first6=Keri |last7=Gough |first7=Clair |last8=Hache |first8=Frederic |last9=Hoolohan |first9=Claire |last10=Hultman |first10=Martin |last11=Hällström |first11=Niclas |last12=Kartha |first12=Sivan |last13=Klinsky |first13=Sonja |last14=Kuchler |first14=Magdalena |last15=Lövbrand |first15=Eva |display-authors=etal |date=18 October 2021 |title=Three Decades of Climate Mitigation: Why Haven't We Bent the Global Emissions Curve? |url=https://doi.org/10.1146/annurev-environ-012220-011104 |journal=Annual Review of Environment and Resources |language=en |volume=46 |issue=1 |pages=653–689 |doi=10.1146/annurev-environ-012220-011104 |issn=1543-5938 |s2cid=233815004 |access-date=31 August 2022 |last16=Nasiritousi |first16=Naghmeh |last17=Newell |first17=Peter |last18=Peters |first18=Glen P. |last19=Sokona |first19=Youba |last20=Stirling |first20=Andy |last21=Stilwell |first21=Matthew |last22=Spash |first22=Clive L. |last23=Williams |first23=Mariama |hdl=1983/93c742bc-4895-42ac-be81-535f36c5039d|hdl-access=free }}</ref><ref>{{Cite book |last1=Mann |first1=Michael E. |title=The Madhouse Effect |last2=Toles |first2=Tom |publisher=Columbia University Press |year=2016 |isbn=978-0231541817 |location=New York Chichester, West Sussex |doi=10.7312/mann17786}}</ref> attempting to ].<ref>{{Cite book |author1=Oreskes, Naomi |title=Merchants of doubt : how a handful of scientists obscured the truth on issues from tobacco smoke to global warming |author2=Conway, Erik |date=2012 |publisher=Bloomsbury |isbn=978-1408824832 |oclc=934374946}}</ref> {{TOC limit|limit=4}}
=== Intergovernmental Panel on Climate Change (IPCC) 2007 ===
{{main|Intergovernmental Panel on Climate Change}}


== Existence of a scientific consensus ==
In February 2007, the IPCC released a summary of the forthcoming ]. According to this summary, the Fourth Assessment Report finds that human actions are "very likely" the cause of global warming, meaning a 90% or greater probability.<ref>{{cite news |title=Warming 'very likely' human-made |url=http://news.bbc.co.uk/2/hi/science/nature/6321351.stm |work=] |publisher=] |date=] |accessdate=2007-02-01 }}</ref>
]


Studies of the scientific opinion on climate change have been undertaken since the 1970s,<ref name="NDU1978" /> and they have been establishing widespread consensus since the 1990s,<ref name="Stewart1992" /><ref name="BrayvonStorch1999" /> with the level of agreement increasing over time.<ref>{{Cite journal |last1=Cook|first1=John |last2=Oreskes|first2=Naomi |last3=Doran|first3=Peter T. |last4=Anderegg|first4=William R. L. |last5=Verheggen|first5=Bart |last6=Maibach|first6=Ed W. |last7=Carlton|first7=J. Stuart |last8=Lewandowsky|first8=Stephan |last9=Skuce|first9=Andrew G. |last10=Green|first10=Sarah A. |last11=Nuccitelli|first11=Dana |last12=Jacobs|first12=Peter |last13=Richardson|first13=Mark |last14=Winkler|first14=Bärbel |last15=Painting|first15=Rob |last16=Rice|first16=Ken |date=2016|title=Consensus on consensus: a synthesis of consensus estimates on human-caused global warming|journal=Environmental Research Letters|language=en|volume=11|issue=4|page=048002|doi=10.1088/1748-9326/11/4/048002|issn=1748-9326|bibcode=2016ERL....11d8002C|doi-access=free}}</ref> Individual scientists, universities, and laboratories contribute to the scientific opinion on climate change via their ] ], while the scientific bodies of national or international standing summarise the areas of collective agreement and relative certainty in ].<ref name="Oreskes_consensus" />
] reports on the report:
:The world's leading climate scientists said global warming has begun, is ''very likely'' caused by man, and will be unstoppable for centuries, ... . The phrase ''very likely'' translates to a more than 90 percent certainty that global warming is caused by man's burning of fossil fuels. That was the strongest conclusion to date, making it nearly impossible to say natural forces are to blame.<ref> Rosenthal, Elisabeth for The New York Times, ] ]</ref>


Examples of such reports include or the 2004 ] from the ] and the governments of the ],<ref name="amap" /><ref name="Impacts of a Warming Arctic: Arctic Climate Impact Assessment New Scientific Consensus: Arctic Is Warming Rapidly" /> or the United States' ], which has been released periodically since 2000 under the auspices of the ]. The fourth NCA, released in 2017, involved the efforts of thirteen federal agencies, led by the ] (NOAA),<ref name="USGCRP participants">{{cite web|url=https://www.globalchange.gov/agencies|title=US Government Agencies Participating in the USGCRP|date=20 October 2008 |work=Agencies|publisher=USGCRP|access-date=November 23, 2018}}</ref> and around "1,000 people, including 300 leading scientists, roughly half from outside the government."<ref name="CNN_Christensen_2018">{{cite news |url=https://www.cnn.com/2018/11/23/health/climate-change-report-bn/index.html |title=Climate change will shrink US economy and kill thousands, government report warns |first1=Jen |last1=Christensen |first2=Michael |last2=Nedelman |newspaper=CNN |date=November 23, 2018 |access-date=November 23, 2018}}</ref>
:The report said that an increase in hurricane and tropical cyclone strength since 1970 ''more likely than not'' can be attributed to man-made global warming. The scientists said global warming's connection varies with storms in different parts of the world, but that the storms that strike the Americas are global warming-influenced.<ref> Stevens, William for The New York Times, ] ]</ref>


The ] (IPCC) had been formed by the ] in 1988,<ref>{{cite web |title=About the IPCC |url=https://www.ipcc.ch/about/ |access-date=22 February 2019 |publisher=Intergovernmental Panel on Climate Change}}</ref><ref>{{cite web |title=UN General Assembly Resolution 43/53 "Protection of global climate for present and future generations of mankind" |url=https://documents-dds-ny.un.org/doc/RESOLUTION/GEN/NR0/530/32/IMG/NR053032.pdf?OpenElement |website=UN General Assembly Resolutions 43rd Session 1988–1989 |publisher=United Nations}}</ref> and it presents reports summarizing the strength and extent of consensus on climate change and ] to the ], with the major reports released at 5-to-7-year intervals starting from 1990.<ref>{{cite web |title=Annex C to Appendix C to the Principles Governing IPCC Work |url=https://www.ipcc.ch/documentation/procedures/ |website=IPCC Procedures |publisher=IPCC}}</ref>{{excerpt|Intergovernmental Panel on Climate Change#Assessment reports|paragraph=1|hat=no}}
The ] summarizes the position on sea level rise:
:On sea levels, the report projects rises of 7-23 inches by the end of the century. That could be augmented by an additional 4-8 inches if recent surprising polar ice sheet melt continues.<ref> Fox News, ] ]</ref>


In 2001, science academies from 17 countries (Australia, ], Brazil, Canada, China, France, Germany, India, ], Ireland, Italy, ], New Zealand, Sweden, ], ] and the United Kingdom made a joint statement endorsing the work of IPCC. They concurred that the temperatures are rising and will continue to rise due to human activities, and also stressed the importance of cutting ], concluding that "Business as usual is no longer a viable option". It is also notable for being one of the first statements to explicitly use the term "consensus".<ref name="The Science of Climate Change" /> In 2005, another joint statement from the science academies of major countries (Brazil, Canada, China, France, Germany, India, Italy, Japan, Russia, United Kingdom and the United States referred to the conclusions of the IPCC as "the international scientific consensus", and urged prompt action on both ] and ].<ref name="nationalacademies21" /> Elsewhere around the world, other organizations to have referred to the scientific consensus include ] in 2007,<ref name="NASAC2007" /> and the ] in 2008.<ref name="inqua" />
=== Joint science academies’ statement 2007 ===
In preparation for the 2007 ], the national science academies of the ] nations issued a declaration referencing the position of the 2005 ''joint science academies' statement'', and acknowledging the confirmation of their previous conclusion by recent research. Following the ], the states:
:It is unequivocal that the climate is changing, and it is very likely that this is predominantly caused by the increasing human interference with the atmosphere. These changes will transform the environmental conditions on Earth unless counter-measures are taken.


In 2013, a study which found that out of over 4,000 ] papers on climate science published since 1990, 97% agree, explicitly or implicitly, that global warming is happening and is human-caused.<ref>{{cite journal |last1=Cook |first1=John |last2=Nuccitelli |first2=Dana |last3=Green |first3=Sarah A. |last4=Richardson |first4=Mark |last5=Winkler |first5=Bärbel |last6=Painting |first6=Rob |last7=Way |first7=Robert |last8=Jacobs |first8=Peter |last9=Skuce |first9=Andrew |title=Quantifying the consensus on anthropogenic global warming in the scientific literature |journal=Environ. Res. Lett. |date=15 May 2013 |volume=8 |issue=2 |pages=024024 |doi=10.1088/1748-9326/8/2/024024 |publisher=IOP Publishing Ltd.|doi-access=free |bibcode=2013ERL.....8b4024C}}</ref><ref>{{cite web |title=Scientific and Public Perspectives on Climate Change / Scientists' vs. Public Understanding of Human-Caused Global Warming |url=https://climatecommunication.yale.edu/publications/scientific-and-public-perspectives-on-climate-change/ |website=climatecommunication.yale.edu |publisher=Yale University |archive-url=https://web.archive.org/web/20190417081857/http://climatecommunication.yale.edu/publications/scientific-and-public-perspectives-on-climate-change/ |archive-date=17 April 2019 |date=29 May 2013 |url-status=live}}</ref> Surveys of scientists' views on climate change – with a focus on human caused climate change – have been undertaken since the 1970s.<ref name="NDU1978" /><ref name="Stewart1992" /> A 2016 reanalysis confirmed that "the finding of 97% consensus in published climate research is robust and consistent with other surveys of climate scientists and peer-reviewed studies."<ref>{{citation |title=Consensus on consensus: a synthesis of consensus estimates on human-caused global warming |first1=John |last1=Cook |first2=Naomi |last2=Oreskes |first3=Peter T. |last3=Doran |first4=William R. L. |last4=Anderegg |first5=Bart |last5=Verheggen |first6=Ed W. |last6=Maibach |first7=J. Stuart |last7=Carlton |first8= Stephan |last8=Lewandowsky |first9= Andrew G. |last9=Skuce|first10=Sarah A. |last10=Green |date=2016 |journal=Environmental Research Letters |volume=11 |pages=048002 |number=44 |doi=10.1088/1748-9326/11/4/048002 |bibcode=2016ERL....11d8002C |doi-access=free}}048002</ref> A 2019 study found scientific consensus to be at 100%,<ref name="Powell2019" /> and a 2021 study found that consensus exceeded 99%.<ref name="EnvRschLtrs_20211019" />
=== Joint science academies’ statement 2005 ===
In 2005 the national science academies of the ] nations, plus ], ] and ], three of the largest emitters of greenhouse gases in the developing world, signed a statement on the global response to climate change. The statement stresses that the scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action<ref> ] ]</ref>, and explicitly endorsed the IPCC consensus. The eleven signatories were the science academies of ], ], ], ], ], ], ], ], ], the ], and the ].


==Consensus points==
=== Joint science academies’ statement 2001 ===
]) of long-lived atmospheric greenhouse gases has nearly doubled in 40 years.<ref name=NOAA_AGGI_2023>{{cite web |title=The NOAA Annual Greenhouse Gas Index (AGGI) |url=https://gml.noaa.gov/aggi/aggi.html |website=NOAA.gov |publisher=National Oceanic and Atmospheric Administration (NOAA) |archive-url=https://web.archive.org/web/20241005195609/https://gml.noaa.gov/aggi/aggi.html |archive-date=5 October 2024 |date=2024 |url-status=live }}</ref>]]
In 2001, following the publication of the ], sixteen national science academies issued a joint statement explicitly acknowledging the IPCC position as representing the scientific consensus on climate change science. The sixteen science academies that issued the statement were those of ], ], ], ], the ], ], ], ], ], ], ], ], ], ], ], and the ].<ref> from ''www.royalsociety.org''</ref>
The scientific consensus regarding ] and mechanisms of ], ] and what should be done about it (]) is that:


* It is "unequivocal" and "incontrovertible" that the ] from human activities have caused warming on land, in ] and in the ]. There are no natural processes which can provide an alternate explanation.<ref name="IPCC_AR6_WGI_SPM" />{{rp|4}}<ref name="NCAR5_Ch2" />{{rp|4}}
=== U.S. National Research Council, 2001 ===
* The atmospheric levels of ] are the highest they have been in at least 2&nbsp;million years,<ref name="IPCC_AR6_WGI_SPM" />{{rp|8}} if not 3.2&nbsp;million years.<ref name="NCAR5_Ch2" />{{rp|11}} The atmospheric levels of two other major greenhouse gases, ] and ], are the highest they have been in at least the past 800,000 years. The record of the past 800,000 years also shows that the increases in their concentrations seen since 1750 would take ] to be caused by natural processes.<ref name="IPCC_AR6_WGI_SPM" />{{rp|8}}
In 2001 the Committee on the Science of Climate Change of the ] published ''Climate Change Science: An Analysis of Some Key Questions'' <ref></ref>. This report explicitly endorses the IPCC view of attribution of recent climate change as representing the view of the scientific community:
* The decade of ] has been {{convert|1.1|C-change|F-change}} warmer than the late 19th century, and the warmest since the start of a consistent ].<ref name="IPCC_AR6_WGI_SPM" />{{rp|5}}<ref name="NCAR5_Ch2" />{{rp|4}} The warming of the past 50 years has occurred faster than any other warming over the past 2,000 years, if not longer.<ref name="IPCC_AR6_WGI_SPM" />{{rp|8}}<ref name="NCAR5_Ch2" />{{rp|11}}
* ] appears to have been increasing since 1950, but the rainfall patterns ], and there is more evidence for increases in heavy precipitation which causes ]s.<ref name="IPCC_AR6_WGI_SPM" />{{rp|5,9}}<ref name="NCAR5_Ch2" />{{rp|10,18}}
* Global sea level has increased by {{cvt|20–25|cm|in|frac=2}} since 1900, with half of that increase occurring since 1980. This ] has been the fastest in "at least the last 3000 years", which is very likely to have been caused by human activity.<ref name="IPCC_AR6_WGI_SPM" />{{rp|5,8}}<ref name="NCAR5_Ch2" />{{rp|4}}
* As the recent warming ], its water expands in volume. This causes half of the recent sea level rise, with the rest due to the warming melting the ]s and ]s.<ref name="IPCC_AR6_WGI_SPM" />{{rp|11}}<ref name="NCAR5_Ch2" />{{rp|35}}
* While there have always been ] and ] events (e.g. ]s, ]s, ]s, ]s, ]s, precipitation extremes), climate change has made many of them more severe, more frequent, or more likely to co-occur, in every part of the globe.<ref name="IPCC_AR6_WGI_SPM" />{{rp|8–9, 15–16}}<ref name="NCAR5_Ch2" />{{rp|4, 20}}
* The dangers of extreme weather events will continue increasing unless there is a rapid decrease in greenhouse gas emissions needed to curb further warming.<ref name="IPCC_AR6_WGI_SPM" />{{rp|15}}<ref name="NCAR5_Ch2" />{{rp|33}}
* Increased warming will lead to worse impacts.<ref name="IPCC_AR6_WGI_SPM" />{{rp|15}}<ref name="NCAR5_Ch2" />{{rp|21}}
* The extent of human-caused emissions will be the main cause of future warming.<ref name="IPCC_AR6_WGI_SPM" />{{rp|13,15}}<ref name="NCAR5_Ch2" />{{rp|35}}


== Statements by major scientific organizations about climate change ==
:The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability. Human-induced warming and associated sea level rises are expected to continue through the 21st century... The IPCC's conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue.<ref></ref>
{{Main|List of statements by major scientific organizations about climate change}}
Many of the major scientific organizations about climate change have issued formal statements of opinion. The vast majority of these statements concur with the IPCC view, some very few are non-committal, or dissent from it. The California Governor's Office website lists nearly 200 worldwide scientific organizations who hold the position that climate change has been caused by human action.<ref>{{cite web|title=List of Worldwide Scientific Organizations|url=https://www.opr.ca.gov/facts/list-of-scientific-organizations.html|publisher=California Governor's Office of Planning and Research|archive-url=https://web.archive.org/web/20240223070755/https://www.opr.ca.gov/facts/list-of-scientific-organizations.html|archive-date=23 February 2024|url-status=live|access-date=10 August 2024}}</ref>


==Surveys of scientists' views on climate change==
=== American Meteorological Society ===
{{See also|History of climate change science}}
The ] (AMS) statement adopted by their council in 2003 said:


===1970s===
: There is now clear evidence that the mean annual temperature at the Earth's surface, averaged over the entire globe, has been increasing in the past 200 years. There is also clear evidence that the abundance of greenhouse gases in the atmosphere has increased over the same period. In the past decade, significant progress has been made toward a better understanding of the climate system and toward improved projections of long-term climate change... Human activities have become a major source of environmental change. Of great urgency are the climate consequences of the increasing atmospheric abundance of greenhouse gases... Because greenhouse gases continue to increase, we are, in effect, conducting a global climate experiment, neither planned nor controlled, the results of which may present unprecedented challenges to our wisdom and foresight as well as have significant impacts on our natural and societal systems.<ref> from ''www.ametsoc.org''</ref>
] ("NCA4", USGCRP, 2017) includes charts<ref>{{cite journal |title=Climate Science Special Report: Fourth National Climate Assessment, Volume I – Chapter 3: Detection and Attribution of Climate Change |url=https://science2017.globalchange.gov/chapter/3/ |website=science2017.globalchange.gov |publisher=U.S. Global Change Research Program (USGCRP) |archive-url=https://web.archive.org/web/20190923190450/https://science2017.globalchange.gov/chapter/3/ |archive-date=23 September 2019 |date=2017 |pages=1–470 |url-status=live}} Adapted directly from Fig. 3.3.</ref> illustrating how human factors, especially accumulation in the atmosphere of greenhouse gases, are the predominant cause of observed global warming.<ref name="4thNationalClimateAssessment_20181123" /> In the 1970s, these factors were less well-understood, and some scientists thought volcanic activity would have a stronger cooling effect than what we know now.]]
In 1978, the ] of the United States had surveyed 24 experts about the near-term climate change and its ]. The majority of respondents had expected some warming to occur between 1970 and 2000, and described human emissions of carbon dioxide as the primary cause, but there was a disagreement on the extent, and a few had thought that an increase in volcanic activity would offset carbon dioxide emissions by elevating atmospheric ] concentrations (which have a reflective effect, also associated with ], and with some ] proposals) and result in overall cooling. When NDU had combined their predictions, they estimated a 10% likelihood of large (~{{convert|0.6|C-change|F-change}}) cooling occurring by 2000, a 25% likelihood of smaller cooling around {{convert|0.15|C-change|F-change}}, a 30% likelihood of limited change, with around {{convert|0.1|C-change|F-change}} warming, a 25% likelihood of "moderate" warming of ~{{convert|0.4|C-change|F-change}}, and a 10% likelihood of large warming of around {{convert|1|C-change|F-change}}.<ref name="NDU1978" /> Subsequently, about {{convert|0.5|C-change|F-change}} had occurred between 1950 and 2000, with about {{convert|0.4|C-change|F-change}} since 1970,<ref>{{Cite web |last=Roper |first=Willem |title=Global Warming Chart – Here's How Temperatures Have Risen Since 1950 |date=25 January 2021 |url=https://www.weforum.org/agenda/2021/01/global-warming-chart-average-temperatures-rising/ |publisher=] |access-date=5 November 2023}}</ref> largely matching the survey's "moderate global warming" scenario.


===1980s===
=== American Geophysical Union ===
In 1989, David H. Slade had surveyed 21 climate scientists, of whom 17 had expressed "a strong belief" in "the reality of a significant climate change".<ref>{{cite journal |last1=Slade |first1=David H. |year=1989 |title=A survey of informed opinion regarding the nature and reality of a 'global greenhouse warming' |journal=Climatic Change |volume=16 |pages=1–4 |doi=10.1007/BF00137342 |s2cid=153884762}}</ref><ref name="Stewart1992" />
The ] (AGU) statement <ref>http://www.agu.org/sci_soc/policy/positions/climate_change2008.shtml</ref> adopted by the society in 2003 and revised in 2007 affirms that rising levels of greenhouse gases have caused and will continue to cause the global surface temperature to be warmer:


=== 1990s ===
:The Earth's climate is now clearly out of balance and is warming. Many components of the climate system—including the temperatures of the atmosphere, land and ocean, the extent of sea ice and mountain glaciers, the sea level, the distribution of precipitation, and the length of seasons—are now changing at rates and in patterns that are not natural and are best explained by the increased atmospheric abundances of greenhouse gases and aerosols generated by human activity during the 20th century. Global average surface temperatures increased on average by about 0.6°C over the period 1956–2006. As of 2006, eleven of the previous twelve years were warmer than any others since 1850. The observed rapid retreat of Arctic sea ice is expected to continue and lead to the disappearance of summertime ice within this century. Evidence from most oceans and all continents except Antarctica shows warming attributable to human activities. Recent changes in many physical and biological systems are linked with this regional climate change. A sustained research effort, involving many AGU members and summarized in the 2007 assessments of the Intergovernmental Panel on Climate Change, continues to improve our scientific understanding of the climate.
In March 1990, Cutter Information Corporation (now known as ]) sent questionnaires to 1500 researchers who were on the attendance lists of climate change conferences, and received 331 responses from 41 countries. The survey revealed widespread agreement that global warming is already happening, that it will result in negative impacts such as ], and that reducing carbon dioxide emissions and halting ] is an appropriate response to it. Only 1.9% of respondents predicted that there would be an overall cooling across the next 100 years. There was more disagreement on the strength of future warming: i.e. around 30% believed that there was a less than 50% chance that the warming would reach or exceed {{convert|2|C-change|F-change}} over the next 100 years, while a larger fraction (almost 40%) thought such temperatures were at least 75% likely.<ref>{{cite report |title=GECR climate survey shows strong agreement on action, less so on warming |publisher=Global Environmental Change Report |year=1990 |volume=2 |issue=9 |pages=1–3}}</ref><ref name="Stewart1992" />


In 1991, the Center for Science, Technology, and Media sent a survey of 6 questions to around 4000 ocean and atmospheric scientists from 45 countries, and received 118 responses by January 1992, with 91% from North America. Out of those 118 scientists, 73 have either agreed or "strongly" agreed with the statement "There is little doubt among scientists that global mean temperature will increase", while 27 had disagreed and only 9 had "strongly disagreed", with the remaining 9 "neutral". 58 scientists had agreed that the ] are expected to be "substantial" by the scientific community as a whole, with 36 disagreeing and 21 staying neutral. Finally, when asked about the 1990 IPCC estimate of warming proceeding at {{convert|0.3|F-change|C-change}} per decade throughout the 21st century under the business-as-usual ], 13 (15%) expressed skepticism, 39 (44%) had emphasized uncertainty, and 37 (42%) had agreed. 52% thought the rate of warming would likely be lower, and 8% thought it would be higher.<ref name="Stewart1992" /> As of 2023, the rate of warming had been {{convert|0.2|F-change|C-change}} or less.<ref>{{Cite news|url=https://phys.org/news/2023-06-world-decade-scientists.html |title=World warming at record 0.2 C per decade, scientists warn |website=] |access-date=23 November 2023}}</ref>
=== American Institute of Physics ===
The Governing Board of the ] endorsed the AGU statement on human-induced climate change:<ref>, American Institute of Physics, 2003</ref>


In 1996, Dennis Bray and ], a pair of researchers at the Helmholtz Research Centre's Institute for Coastal Research, sent a ] over mail to 1000 climate scientists in Germany, the United States and Canada. 40% responded, and the results subsequently published in the ] in 1999. On a scale of 1 out of 7, where ''higher'' numbers indicated greater ''disagreement'', "global warming is already underway" had a mean rating of 3.4, and "global warming will occur in the future" had an even greater agreement of 2.6 Surveyed scientists had less confidence in the accuracy of contemporary ]s, rating their ability to make "reasonable predictions" 10 years out at 4.8, and 5.2 for 100-year predictions: however, they consistently rejected the notion that there was too much uncertainty to justify taking immediate action, with a mean 5.6 out of 7 rating. In fact, they usually agreed there was substantial uncertainty about how strongly the impacts will affect society, and that many changes would likely be necessary ].<ref name="BrayvonStorch1999" />
:The Governing Board of the American Institute of Physics has endorsed a position statement on climate change adopted by the American Geophysical Union (AGU) Council in December 2003.


=== American Astronomical Society === === 2000–2004 ===
In 2003, Bray and von Storch repeated their 1996 survey, using the same response structure with ratings on a 1–7 scale, and including all of the original questions. Further, new questions were added, which were devoted to ] and ]. This second survey received 530 responses from 27 different countries, but it has been strongly criticized on the grounds that it was performed on the web with no means to verify that the respondents were climate scientists or to prevent multiple submissions. While the survey required entry of a username and password, its critics alleged that both were circulated to non-scientists, including to a ] mailing list. Bray and von Storch defended their results, claiming that a ] with a ] and a ] revealed no significant irregularities.<ref name="BrayvonStorch2003" />
The ] has endorsed the AGU statement:<ref>, American Astronomical Society, 2004</ref>


In general, the second survey had demonstrated an increase in scientific confidence relative to the first. One of the greatest increases was for the statement "We can say for certain that global warming is a process already underway", where 1 represented strong agreement and 7 strong disagreement: the mean response went from 3.39 to 2.41. In response to the question, "To what extent do you agree or disagree that climate change is mostly the result of anthropogenic causes?", it went from 4.17 to 3.62.<ref name="BrayvonStorch2003" /> Notably, the percentage of respondents "strongly disagreeing" stayed the same, at 10%, and a similar percentage stayed neutral (14% in 1996 and 13% in 2003): yet, the overall split went from 41% agreement and 45% disagreement in 1996 to 56% agreement and 30% disagreement in 2003, as there was both a substantial increase in agreement and a decline percentage of those disagreeing less strongly.<ref>{{cite web |title=Climate scientists' views on climate change: a survey |date=8 August 2007 |url=http://blogs.nature.com/climatefeedback/2007/08/climate_scientists_views_on_cl_1.html |url-status=dead |archive-url=https://web.archive.org/web/20120113114849/http://blogs.nature.com/climatefeedback/2007/08/climate_scientists_views_on_cl_1.html |archive-date=13 January 2012 |publisher=]}}</ref> Similarly, there was a 72% to 20% split in favour of describing the IPCC reports as accurate, and a 15% to 80% rejection of the thesis that "there is enough uncertainty about the phenomenon of global warming that there is no need for immediate policy decisions."<ref name="BrayvonStorch2003" />
:In endorsing the "Human Impacts on Climate" statement , the AAS recognizes the collective expertise of the AGU in scientific subfields central to assessing and understanding global change, and acknowledges the strength of agreement among our AGU colleagues that the global climate is changing and human activities are contributing to that change.


In 2004, the geologist and historian of science ] analyzed the ] of 928 scientific papers on "global climate change" published between 1993 and 2003. 75% had either explicitly expressed support for the ] on anthropogenic climate change, or had accepted it as a given and were focused on evaluating its ] or proposing approaches for ], while the remaining 25% were devoted to methods of current climate change research or ] analysis. No abstract had explicitly rejected the scientific consensus.<ref>{{cite journal | author=Naomi Oreskes | date=3 December 2004 | title=Beyond the Ivory Tower: The Scientific Consensus on Climate Change | journal=Science | volume=306 | issue=5702 | page=1686 | doi=10.1126/science.1103618 | url=http://www.sciencemag.org/cgi/reprint/306/5702/1686.pdf | pmid=15576594| s2cid=153792099 | doi-access=free}}</ref>
=== American Physical Society ===
"Emissions of greenhouse gases from human activities are changing the atmosphere in ways that affect the Earth's climate. Greenhouse gases include carbon dioxide as well as methane, nitrous oxide and other gases. They are emitted from fossil fuel combustion and a range of industrial and agricultural processes.


=== 2005–2009 ===
"The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now."<ref>, American Physical Society, 2007</ref>
]
In 2007, ] surveyed 489 randomly selected members of either the ] or the ] for the ] (STATS) at ], publishing the results in April 2008. 97% of the scientists surveyed agreed that global temperatures had increased during the past 100 years, and only 5% believed that human activity does not contribute to greenhouse warming. 84% said they personally believed human-induced warming was occurring, and 74% agreed that "currently available scientific evidence" substantiated its occurrence. 56% described the study of global climate change as a mature science and 39% as an emerging science. When asked about the likely severity of ] over the next 50–100 years, 41% said they could be described as catastrophic; 44% thought the effects would be moderately dangerous while about 13% thought there was relatively little danger.<ref>{{cite web |last=Lichter |first=S. Robert |url=http://stats.org/stories/2008/global_warming_survey_apr23_08.html |title=Climate Scientists Agree on Warming, Disagree on Dangers, and Don't Trust the Media's Coverage of Climate Change |publisher=Statistical Assessment Service, George Mason University |date=24 April 2008 |access-date=20 January 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100111104946/http://stats.org/stories/2008/global_warming_survey_apr23_08.html |archive-date=11 January 2010}}</ref><ref>{{cite news|url=http://journalistsresource.org/studies/environment/climate-change/structure-scientific-opinion-climate-change/|title="Structure of Scientific Opinion on Climate Change" |publisher=Journalist's Resource.org}}</ref><ref name="The Structure of Scientific Opinion on Climate Change" /><ref>{{cite web |last= Lavelle |first= Marianne|url=https://www.usnews.com/articles/news/national/2008/04/23/survey-tracks-scientists-growing-climate-concern.html |title=Survey Tracks Scientists' Growing Climate Concern |publisher=U.S. News & World Report |date=23 April 2008 |access-date=20 January 2010}}</ref>


The third Dennis Bray and ] survey was also conducted in 2008, with the results published in 2010. It used the same methodology as their two previous surveys, with a similar number of sections and also asking to rate responses on a 1-to-7 scale (i.e. from 'not at all' to 'very much'), but it had also introduced web links with respondent-specific unique identifiers to eliminate multiple responses. 2058 climate scientists from 34 countries were surveyed, and a total of 373 responses were received (response rate of 18.2%).
=== Federal Climate Change Science Program, 2006 ===
On May 2, 2006, the Federal Climate Change Science Program commissioned by the Bush administration in 2002 released the first of 21 assessments. Though it did not state what percentage of climate change might be anthropogenic, the assessment concluded:
:Studies ... show clear evidence of human influences on the climate system (due to changes in greenhouse gases, aerosols, and stratospheric ozone). ... The observed patterns of change over the past 50 years cannot be explained by natural processes alone, nor by the effects of short-lived atmospheric constituents (such as aerosols and tropospheric ozone) alone.<ref> ''www.climatescience.gov''</ref>


To the question "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 67.1% said they very much agreed (7), 26.7% agreed to some large extent (6), 6.2% said to they agreed to some small extent (2–4), none said they did not agree at all. To the question "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?" the responses were 34.6% very much agree, 48.9% agreeing to a large extent, 15.1% to a small extent, and 1.35% not agreeing at all. Similarly, 34.6% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 27.6% agreed to a large extent, while only 1.1% did not agree at all.
===American Association for the Advancement of Science===
The ] stated,
"The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society."<ref> ''www.aaas.org'' ] ]</ref>


At the same time, the respondents had strongly rejected the concept of intentionally presenting the most extreme possibilities in the hope of mobilizing the public, with around 73% disagreeing (1–3), 12.5% unsure and 14.5% agreeing in any way (5–7). Only 1.6% had agreed very much, while 27.2% did not agree at all, even as they overwhelmingly agreed (84% vs. 4%) that the scientists who do this are the most likely to be listened to by journalists. The respondents have generally expressed high confidence in the IPCC reports, with 63.5% agreeing that they estimated the impacts of temperature change exactly right (4 on the scale), and only 1.4% responding that they had strongly underestimated and 2.5% that they had strongly overestimated those impacts (1 and 7 on a scale.) On ], 51.4% thought the reports were exactly right, and only about 16% thought it was overestimated in any way (5–7), while the remaining third believed it was underestimated (1–3).<ref>{{cite web |first1=Dennis |last1=Bray |first2=Hans |last2=von Storch |year=2010 |url=https://ncse.ngo/files/pub/polls/2010--Perspectives_of_Climate_Scientists_Concerning_Climate_Science_&_Climate_Change_.pdf |title=A Survey of the Perspectives of Climate Scientists Concerning Climate Science and Climate Change}}</ref><ref>{{cite journal |last=Bray |first=Dennis |date=August 2010 |title=The scientific consensus of climate change revisited |url=http://www.hzg.de/imperia/md/content/gkss/zentrale_einrichtungen/bibliothek/journals/2010/Bray-envscipol.pdf |journal=Environmental Science & Policy |volume=13 |issue=5 |pages=340–350 |doi=10.1016/j.envsci.2010.04.001}}, copy online at </ref><ref>{{cite journal|author=Bray, D.|author2=von Storch H. |year=2009 |title=Prediction' or 'Projection; The nomenclature of climate science |journal=] |volume=30 |pages=534–543 |doi=10.1177/1075547009333698 |issue=4|s2cid=145338218 |url=http://www.hzg.de/imperia/md/content/gkss/zentrale_einrichtungen/bibliothek/journals/2009/bray_27111.pdf}}</ref> Subsequent IPCC reports had been forced to regularly increase their estimates of future sea level rise, largely in response to newer research on the ]s of ] and ].<ref>{{cite news |title=Ice sheet melt on track with 'worst-case climate scenario' |language=en |work=www.esa.int |url=https://www.esa.int/Applications/Observing_the_Earth/Space_for_our_climate/Ice_sheet_melt_on_track_with_worst-case_climate_scenario |access-date=8 September 2020}}</ref><ref>{{cite journal |last1=Slater |first1=Thomas |last2=Hogg |first2=Anna E. |last3=Mottram |first3=Ruth |author-link3=Ruth Mottram |date=31 August 2020 |title=Ice-sheet losses track high-end sea-level rise projections |url=https://www.nature.com/articles/s41558-020-0893-y |journal=Nature Climate Change |language=en |volume=10 |issue=10 |pages=879–881 |bibcode=2020NatCC..10..879S |doi=10.1038/s41558-020-0893-y |issn=1758-6798 |archive-url=https://web.archive.org/web/20200902132539/https://www.nature.com/articles/s41558-020-0893-y |archive-date=2 September 2020 |access-date=8 September 2020 |s2cid=221381924}}</ref><ref>{{Cite journal |last1=Grinsted |first1=Aslak |last2=Christensen |first2=Jens Hesselbjerg |date=2021-02-02 |title=The transient sensitivity of sea level rise |url=https://os.copernicus.org/articles/17/181/2021/ |journal=Ocean Science |volume=17 |issue=1 |pages=181–186 |bibcode=2021OcSci..17..181G |doi=10.5194/os-17-181-2021 |issn=1812-0784 |s2cid=234353584 |doi-access=free|hdl=11250/3135359 |hdl-access=free }}</ref><ref>{{Cite journal |last1=Fox-Kemper |first1=B. |last2=Hewitt |first2=H.T.|author2-link=Helene Hewitt |last3=Xiao |first3=C. |last4=Aðalgeirsdóttir |first4=G. |last5=Drijfhout |first5=S.S. |last6=Edwards |first6=T.L. |last7=Golledge |first7=N.R. |last8=Hemer |first8=M. |last9=Kopp |first9=R.E. |last10=Krinner |first10=G. |last11=Mix |first11=A. |date=2021 |editor-last=Masson-Delmotte |editor-first=V. |editor2-last=Zhai |editor2-first=P. |editor3-last=Pirani |editor3-first=A. |editor4-last=Connors |editor4-first=S.L. |editor5-last=Péan |editor5-first=C. |editor6-last=Berger |editor6-first=S. |editor7-last=Caud |editor7-first=N. |editor8-last=Chen |editor8-first=Y. |editor9-last=Goldfarb |editor9-first=L. |title=Chapter 9: Ocean, Cryosphere and Sea Level Change |journal=Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change |url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf |publisher=Cambridge University Press, Cambridge, UK and New York, NY, US |pages=1302}}</ref>
===Stratigraphy Commission of the Geological Society of London===
The Stratigraphy Commission of the ] stated, "We find that the evidence for human-induced climate change is now persuasive, and the need for direct action compelling."<ref> ''www.geolsoc.org.uk''</ref>


In 2009, ] and Maggie Kendall Zimmerman at ] polled 10,257 ]s from various specialities and received replies from 3,146. 79 respondents were ] who had published over half of their ] research on the subject of climate change, and 76 of them agreed that mean global temperatures had risen compared to pre-1800s levels, with 75 describing human activity as a significant factor. Among all respondents, 90% agreed that temperatures have risen compared to pre-1800 levels, and 82% agreed that humans significantly influence the global temperature. ]s and ]s were among the biggest doubters, with only 47 percent and 64 percent, respectively, believing in significant human involvement. In summary, Doran and Zimmerman wrote:<ref>{{cite journal|first1=Peter T.|last1=Doran |last2=Zimmerman |first2=Maggie Kendall |date=20 January 2009 |title=Examining the Scientific Consensus on Climate Change |journal=] |volume=90 |issue=3 |pages=22–23 |doi=10.1029/2009EO030002 |url=https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2009EO030002 |bibcode=2009EOSTr..90...22D |s2cid=128398335}}</ref>
===Geological Society of America===
"The ] (GSA) supports the scientific conclusions that Earth’s climate is changing; the climate changes are due in part to human activities; and the probable consequences of the climate changes will be significant and blind to geopolitical boundaries. Furthermore, the potential implications of global climate change and the time scale over which such changes will likely occur require active, effective, long-term planning."<ref> Position Statement</ref>


{{blockquote|It seems that the debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes.}}
===American Chemical Society===
The ] stated:
:Careful and comprehensive scientific assessments have clearly demonstrated that the Earth’s climate system is changing rapidly in response to growing atmospheric burdens of greenhouse gases and absorbing aerosol particles (IPCC, 2007). There is very little room for doubt that observed climate trends are due to human activities. The threats are serious and action is urgently needed to mitigate the risks of climate change.
:<br>
:The reality of global warming, its current serious and potentially disastrous impacts on Earth system properties, and the key role emissions from human activities play in driving these phenomena have been recognized by earlier versions of this ACS policy statement (ACS, 2004), by other major scientific societies, including the American Geophysical Union (AGU, 2003), the American Meteorological Society (AMS, 2007) and the American Association for the Advancement of Science (AAAS, 2007), and by the U. S. National Academies and ten other leading national academies of science (NA, 2005). This statement reviews key global climate change impacts and recommends actions required to mitigate or adapt to currently anticipated consequences.<ref>{{cite web | title=Statement on Global Climate Change | publisher=] | year=2007 | accessdate=2008-01-09 | url=http://portal.acs.org/portal/fileFetch/C/WPCP_007661/pdf/WPCP_007661.pdf }}</ref>


=== 2010–2014 ===
===Engineers Australia (The Institution of Engineers Australia)===
A 2010 paper in the ] reviewed publication and citation data for 1,372 climate researchers, 908 of whom had authored 20 or more publications on climate, and found that
"] believes that Australia must act swiftly and proactively in line with global expectations to address climate change as an economic, social and environmental risk... We believe that addressing the costs of atmospheric emissions will lead to increasing our competitive advantage by minimising risks and creating new economic opportunities. Engineers Australia believes the Australian Government should ratify the Kyoto Protocol."<ref> ] ]</ref>


<blockquote>(i) 97–98% of the climate researchers most actively publishing in the field support the tenets of ACC (Anthropogenic Climate Change) outlined by the Intergovernmental Panel on Climate Change, and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.<ref>{{cite journal |title= Expert credibility in climate change|journal= Proceedings of the National Academy of Sciences|volume= 107|issue= 27|pages= 12107–12109|author1=William R. L. Anderegg |author2=James W. Prall |author3=Jacob Harold |author4=Stephen H. Schneider |name-list-style=amp |date= April 9, 2010|doi= 10.1073/pnas.1003187107|pmid = 20566872|pmc= 2901439|bibcode= 2010PNAS..10712107A|doi-access= free}}</ref><ref> by ], "Science Insider", ], 21 June 2010</ref>
=== The Canadian Meteorological and Oceanographic Society ===
</blockquote>
"CMOS endorses the process of periodic climate science assessment carried out by the Intergovernmental Panel on Climate Change and supports the conclusion, in its Third Assessment Report, which states that the balance of evidence suggests a discernible human influence on global climate."<ref> Updated, 2007</ref>


In October 2011, researchers from ] analyzed the results of a survey of 998 actively working scientists from the ], the ], or listed in the 23rd edition of ], 489 of whom had returned completed questionnaires. 97% of respondents had agreed that global temperatures have risen over the past century. 84% agreed that "human-induced greenhouse warming is now occurring," 5% disagreed, and 12% didn't know.<ref>{{cite news|url=http://journalistsresource.org/studies/environment/climate-change/structure-scientific-opinion-climate-change/|title="Structure of Scientific Opinion on Climate Change" at Journalist's Resource.org}}</ref><ref name="FL2011">{{cite journal |url= http://ijpor.oxfordjournals.org/content/early/2011/10/27/ijpor.edr033.short|title= The Structure of Scientific Opinion on Climate Change|journal= International Journal of Public Opinion Research|volume= 24|pages= 93–103|author1=Stephen J. Farnsworth |author2=S. Robert Lichter |date= 27 October 2011|access-date= 2 December 2011 |doi= 10.1093/ijpor/edr033}} Paywalled; full test online , retrieved 30 November 2014. From Table I, "Q: In your opinion, is human-induced greenhouse warming now occurring?" Yes, 84%. No, 5%. Don't Know, 12%</ref> When asked what they regard as "the likely effects of global climate change in the next 50 to 100 years," on a scale of 1 to 10, from Trivial to Catastrophic: 13% of respondents replied 1 to 3 (trivial/mild), 44% replied 4 to 7 (moderate), 41% replied 8 to 10 (severe/catastrophic), and 2% didn't know.<ref name="FL2011" />
==Noncommittal statements==


In 2012, ], a former member of the ], analyzed published research on global warming and climate change between 1991 and 2012 and found that of the 13,950 articles in peer-reviewed journals, only 24 (&lt;0.2%) rejected anthropogenic global warming.<ref>{{citation |title=The State of Climate Science: A Thorough Review of the Scientific Literature on Global Warming |first=James Lawrence |last=Powell |author-link=James L. Powell |date=15 November 2012 |url=https://scienceprogress.org/2012/11/27479/ |work=Science Progress |access-date=21 September 2016}}</ref><ref>{{cite book |isbn=978-0-231-15718-6 |title=The Inquisition of Climate Science |first=James Lawrence |last=Powell |author-link=James L. Powell |publisher=Columbia University Press |date=2011}}</ref><ref>{{cite news|last=Plait|first=P.|date=11 December 2012|title=Why Climate Change Denial Is Just Hot Air|url=http://www.slate.com/blogs/bad_astronomy/2012/12/11/climate_change_denial_why_don_t_they_publish_scientific_papers.html |newspaper=Slate |access-date=12 June 2014}}</ref><ref>{{cite web | url=https://www.motherjones.com/blue-marble/2012/11/chart-only-017-percent-peer-reviewed-papers-question-global-warming | title=CHART: Only 0.17 Percent of Peer-Reviewed Papers Question Global Warming | work=] | date=1 December 2012 | access-date=12 February 2014 | author=Sheppard, Kate}}</ref> This was a follow-up to an analysis looking at 2,258 peer-reviewed articles published between November 2012 and December 2013, which revealed that only one of the 9,136 authors rejected anthropogenic global warming.<ref>{{cite news|last=Plait|first=P.|date=14 January 2014|title=The Very, Very Thin Wedge of Denial |url=http://www.slate.com/blogs/bad_astronomy/2014/01/14/climate_change_another_study_shows_they_don_t_publish_actual_papers.html |newspaper=Slate |access-date=12 June 2014}}</ref><ref>{{cite web | url=http://www.popsci.com/article/science/infographic-scientists-who-doubt-human-caused-climate-change | title=Infographic: Scientists Who Doubt Human-Caused Climate Change | work=] | date=10 January 2014 | access-date=12 February 2014 | author=Gertz, Emily}}</ref><ref>The study in question was: {{Cite journal | doi = 10.1134/S1019331613030015| title = The role of solar activity in global warming| journal = Herald of the Russian Academy of Sciences| volume = 83| issue = 3| pages = 275–285| year = 2013| last1 = Avakyan | first1 = S. V.| bibcode = 2013HRuAS..83..275A| s2cid = 154047107}}</ref>
===American Association of State Climatologists===
The ] statement from the ] noted the difficulties with predicting impacts due to climate change, while acknowledging that human activities are having an effect on climate:
:Climate prediction is difficult because it involves complex, nonlinear interactions among all components of the earth’s environmental system. (...) The AASC recognizes that human activities have an influence on the climate system. Such activities, however, are not limited to greenhouse gas forcing and include changing land use and sulfate emissions, which further complicates the issue of climate prediction. Furthermore, climate predictions have not demonstrated skill in projecting future variability and changes in such important climate conditions as growing season, drought, flood-producing rainfall, heat waves, tropical cyclones and winter storms. These are the type of events that have a more significant impact on society than annual average global temperature trends. Policy responses to climate variability and change should be flexible and sensible – The difficulty of prediction and the impossibility of verification of predictions decades into the future are important factors that allow for competing views of the long-term climate future. Therefore, the AASC recommends that policies related to long-term climate not be based on particular predictions, but instead should focus on policy alternatives that make sense for a wide range of plausible climatic conditions regardless of future climate.<ref> by the American Association of State Climatologists (AASC)</ref>


Dennis Bray and Hans von Storch had conducted their fourth survey in 2013, publishing its results the following year. 283 scientists had responded: 185 (65.4%) had been working in climate science for over 15 years, and only 19 (6.7%) had 0 to 5 years of experience. It had the same methodology as the third survey, ranking responses on a 1-to-7 scale and similar responses to the same questions: i.e., when asked, "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 74.7% said they very much agreed (7), 2.9% were "neutral" (4), and only 2.1% were 1–3 on the scale. To the question "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?", 43% had very much agreed, 28.5% agreeing to a large extent (6), 16.6% to a small extent (2–4), and 2.5% did not agree at all (1). 41.8% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 23.2% agreed to a large extent, while 3.5% did not agree at all. A new question asked respondents to attribute a ''percentage'' of recent warming to anthropogenic causes: 73.3% of scientists attributed 70–100%, while only 1.5% said there was zero human role.<ref>{{cite web |first1=Dennis |last1=Bray |first2=Hans |last2=von Storch |year=2014 |url=https://www.hereon.de/imperia/md/content/hzg/zentrale_einrichtungen/bibliothek/berichte/hzg_reports_2014/hzg_report_2014_4.pdf |title=A survey of the perceptions of climate scientists 2013}}</ref>
===American Association of Petroleum Geologists (AAPG)===
]
The ] (AAPG) Position Statement on climate change states that "the AAPG membership is divided on the degree of influence that anthropogenic CO2 has on recent and potential global temperature increases ... Certain climate simulation models predict that the warming trend will continue, as reported through NAS, AGU, AAAS and AMS. AAPG respects these scientific opinions but wants to add that the current climate warming projections could fall within well-documented natural variations in past climate and observed temperature data. These data do not necessarily support the maximum case scenarios forecast in some models."<ref> from ''http://dpa.aapg.org''</ref>
In 2013, another scientist, John Cook, examined 11,944 abstracts from the peer-reviewed scientific literature from 1991 to 2011 that matched the topics 'global climate change' or 'global warming'.<ref name="John Cook 2013" /> He and his co-authors found that, while 66.4% of them expressed no position on anthropogenic global warming (AGW), of those that did, 97.1% endorsed the consensus position that humans are contributing to global warming. They also invited authors to rate their own papers and found that, while 35.5% rated their paper as expressing no position on AGW (known to be expected in a consensus situation{{sfn|Oreskes|2007|p=72|ps=: " generally focus their discussions on questions that are still disputed or unanswered rather than on matters about which everyone agrees"}}) 97.2% of the rest endorsed the consensus. In both cases the percentage of endorsements among papers expressing a position was marginally increasing over time. They concluded that the number of papers actually rejecting the consensus on AGW is a vanishingly small proportion of the published research, and that "the fundamental science of AGW is no longer controversial among the publishing science community and the remaining debate in the field has moved on to other topics."<ref name="John Cook 2013" />


In 2014, researchers from the ] surveyed 1,868 climate scientists. They found that, consistent with other research, the level of agreement on anthropogenic causation correlated with expertise – 90% of those surveyed with more than 10 peer-reviewed papers related to climate (just under half of survey respondents) explicitly agreed that greenhouse gases were the main cause of global warming.<ref>{{cite journal|last1=Verheggen|first1=Bart|last2=Strengers|first2=Bart|last3=Cook|first3=John|last4=van Dorland|first4=Rob|last5=Vringer|first5=Kees|last6=Peters|first6=Jeroen|last7=Visser|first7=Hans|last8=Meyer|first8=Leo|title=Scientists' Views about Attribution of Global Warming|journal=]|date=19 August 2014|volume=48|issue=16|pages=8963–8971|doi=10.1021/es501998e|pmid=25051508|bibcode=2014EnST...48.8963V|doi-access=}}</ref> They included researchers on mitigation and adaptation in their surveys in addition to physical climate scientists, leading to a slightly lower level of consensus compared to previous studies.<ref>{{Cite journal|last1=Verheggen|first1=Bart|last2=Strengers|first2=Bart|last3=Vringer|first3=Kees|last4=Cook|first4=John|last5=Dorland|first5=Rob van|last6=Peters|first6=Jeroen|last7=Visser|first7=Hans|last8=Meyer|first8=Leo|date=2 December 2014|title=Reply to Comment on "Scientists' Views about Attribution of Global Warming"|journal=Environmental Science & Technology|volume=48|issue=23|pages=14059–14060|doi=10.1021/es505183e|pmid=25405594|issn=0013-936X|bibcode=2014EnST...4814059V|doi-access=free}}</ref>
Prior to the adoption of this statement, the AAPG was the only major scientific organization that rejected the finding of significant human influence on recent climate, according to a statement by the Council of the American Quaternary Association.<ref name=AQAonAAPG>{{cite journal|author=Julie Brigham-Grette et al.|title=Petroleum Geologists‘ Award to Novelist Crichton Is Inappropriate|journal=]|volume=87|issue=36|quote=The AAPG stands alone among scientific societies in its denial of human-induced effects on global warming.|url=http://www.agu.org/fora/eos/pdfs/2006EO360008.pdf|date=September 2006|accessdate=2007-01-23}}</ref> The AAPG updated its statement in part because the previous statement was "not supported by a significant number of our members and prospective members".<ref></ref>


=== 2015–2019 ===
==Statements by dissenting organizations==
]
With the July 2007 release of the by the ], no remaining scientific body of national or international standing is known to reject the basic findings of human influence on recent climate.<ref name=AQAonAAPG/>
A 2016 study titled ''Learning from mistakes in climate research'' followed up on John Cook's 2013 paper by examining the quality of the 3% of peer-reviewed papers which had rejected the consensus view. They discovered that "replication reveals a number of methodological flaws, and a pattern of common mistakes emerges that is not visible when looking at single isolated cases".<ref>{{Cite journal |last1=Benestad |first1=Rasmus E. |last2=Nuccitelli |first2=Dana |last3=Lewandowsky |first3=Stephan |last4=Hayhoe |first4=Katharine |last5=Hygen |first5=Hans Olav |last6=van Dorland |first6=Rob |last7=Cook |first7=John |date=November 2016 |title=Learning from mistakes in climate research |journal=Theoretical and Applied Climatology |language=en |volume=126 |issue=3–4 |pages=699–703 |doi=10.1007/s00704-015-1597-5 |bibcode=2016ThApC.126..699B |issn=0177-798X|doi-access=free}}</ref> That same year, Cook's paper was criticized by ],<ref>{{cite journal | last=Tol | first=Richard S J | title=Comment on 'Quantifying the consensus on anthropogenic global warming in the scientific literature' | journal=Environmental Research Letters | publisher=IOP Publishing | volume=11 | issue=4 | date=1 April 2016 | issn=1748-9326 | doi=10.1088/1748-9326/11/4/048001 | page=048001| bibcode=2016ERL....11d8001T | doi-access=free}}</ref> but strongly defended by a companion paper in the same volume.<ref>{{Cite journal|last1=Cook|first1=John|last2=Oreskes|first2=Naomi|last3=Doran|first3=Peter T.|last4=Anderegg|first4=William R. L.|last5=Verheggen|first5=Bart|last6=Maibach|first6=Ed W.|last7=Carlton|first7=J. Stuart|last8=Lewandowsky|first8=Stephan|last9=Skuce|first9=Andrew G.|last10=Green|first10=Sarah A.|last11=Nuccitelli|first11=Dana|date=April 2016|title=Consensus on consensus: a synthesis of consensus estimates on human-caused global warming|journal=Environmental Research Letters|language=en|volume=11|issue=4|pages=048002|doi=10.1088/1748-9326/11/4/048002|issn=1748-9326|doi-access=free|bibcode=2016ERL....11d8002C}}</ref>


The 5th International Survey of Climate Scientists by Dennis Bray and Hans von Storch took place over December 2015 and January 2016. Unlike the past surveys, the scientists were no longer questioned on their opinion of the IPCC, and there was much more focus on ]. In other ways, it had replicated the methodology of the previous surveys, with most responses ranked on a 1-to-7 scale. There were over 600 complete responses: 291 (45.2%) had been working in climate science for over 15 years, while 79 (12.3%) had 0 to 5 years of experience. When asked "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 79.3% said they very much agreed (7), 1.2% were "neutral" (4), and only 2.1% were 1–3 on the scale. To the question "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?", 47.7% had very much agreed, 26% agreeing to a large extent (6), 9.8% to a small extent (2–4), and 1.9% did not agree at all (1). 46% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 26% agreed to a large extent, while 2.2% did not agree at all. 75.8% said that the level of uncertainty in climate science had decreased since 1996, while 13.6% said it had increased. 75.7% said that the level of risk associated with climate change had increased considerably since 1996, while 5% said it had decreased.<ref>{{cite web |first1=Dennis |last1=Bray |first2=Hans |last2=von Storch |year=2016 |url=https://www.researchgate.net/publication/316170360 |title=The Bray and von Storch 5th International Survey of Climate Scientists 2015/2016 |doi=10.13140/RG.2.2.11802.85443}}</ref>
==Scientific consensus==
A question which frequently arises in conveying the scientific opinion to a broader audience is to what extent that opinion rises to the level of a consensus. Several scientific organizations have explicitly used the term "consensus" in their statements:
*]: "The conclusions in this statement reflect the scientific consensus represented by, for example, the Intergovernmental Panel on Climate Change, and the Joint National Academies' statement."<ref> ] ]</ref>
*]: "In the judgment of most climate scientists, Earth’s warming in recent decades has been caused primarily by human activities that have increased the amount of greenhouse gases in the atmosphere. ... On climate change, have assessed consensus findings on the science..."<ref></ref>
*Joint Science Academies' statement, 2005: "We recognise the international scientific consensus of the Intergovernmental Panel on Climate Change (IPCC)."<ref></ref>
*Joint Science Academies' statement, 2001: "The work of the Intergovernmental Panel on Climate Change (IPCC) represents the consensus of the international scientific community on climate change science. We recognise IPCC as the world’s most reliable source of information on climate change and its causes, and we endorse its method of achieving this consensus."<ref></ref>
*]: "The nature of science is such that there is rarely total agreement among scientists. Individual scientific statements and papers—the validity of some of which has yet to be assessed adequately—can be exploited in the policy debate and can leave the impression that the scientific community is sharply divided on issues where there is, in reality, a strong scientific consensus. ...IPCC assessment reports are prepared at approximately five-year intervals by a large international group of experts who represent the broad range of expertise and perspectives relevant to the issues. The reports strive to reflect a consensus evaluation of the results of the full body of peer-reviewed research. ... They provide an analysis of what is known and not known, the degree of consensus, and some indication of the degree of confidence that can be placed on the various statements and conclusions."<ref> ] ]</ref>


In 2017, James L. Powell analyzed five surveys of the peer-reviewed literature from 1991 to 2015, and found that they amounted to a combined 54,195 articles, few of which had outright rejected anthropogenic climate change, resulting in an average consensus of 99.94%.<ref name="Powell2017" /> In November 2019, his survey of over 11,600 peer-reviewed articles published in the first seven months of 2019 showed that the consensus had reached 100%.<ref name="Powell2019" />
==Surveys of scientists and scientific literature==
Various surveys have been conducted to determine a ] on ]. Few have been conducted within the last ten years.


=== Oreskes, 2004 === === 2020s ===
{{multiple image |total_width=500
A 2004 article by geologist and historian of science ] summarized a study of the scientific literature on climate change.<ref>{{cite journal
| image1= 20211103 Academic studies of scientific consensus - global warming, climate change - vertical bar chart - en.svg | caption1= ''Scientific consensus on causation:'' Academic studies of scientific agreement on human-caused global warming among climate experts (2010–2015) reflect that the level of consensus correlates with expertise in climate science.<ref>{{cite journal |last1=Cook |first1=John |last2=Oreskes |first2= Naomi |last3=Doran |first3=Peter T. |last4=Anderegg |first4=William R. L. |last5=Verheggen |first5=Bart |display-authors=4 |date=2016 |title=Consensus on consensus: a synthesis of consensus estimates on human-caused global warming |journal=Environmental Research Letters |volume=11 |issue=4 |page=048002 |bibcode= 2016ERL....11d8002C |doi= 10.1088/1748-9326/11/4/048002 |doi-access=free}}</ref> A 2019 study found scientific consensus to be at 100%,<ref name="Powell2019" /> and a 2021 study concluded that consensus exceeded 99%.<ref name="EnvRschLtrs_20211019" /> Another 2021 study found that 98.7% of climate experts indicated that the Earth is getting warmer mostly because of human activity.<ref name="Myers_2021" />
| author = Naomi Oreskes
| image2= 20240508 Survey of IPCC lead authors and review editors re expectation of global warming.svg |caption2= In a 2024 survey, 76.3% of responding IPCC lead authors and review editors projected at least 2.5{{nbsp}}°C of global warming by 2100; only 5.79% forecast warming of 1.5{{nbsp}}°C or less.<ref name=Guardian_20240508/> Separately, then-current climate policies indicate the world will have warmed by about 2.7{{nbsp}}°C.<ref name=Guardian_20240508>{{cite news |last1=Carrington |first1=Damian |title=World's top climate scientists expect global heating to blast past 1.5C target |work=The Guardian |url=https://www.theguardian.com/environment/article/2024/may/08/world-scientists-climate-failure-survey-global-temperature |date=8 May 2024 |archive-url=https://web.archive.org/web/20240509191712/https://www.theguardian.com/environment/article/2024/may/08/world-scientists-climate-failure-survey-global-temperature |archive-date=9 May 2024 |url-status=live }} Replies were received from 380 of 843 scientists believed to have been contacted.</ref>
| date = December 3, 2004 (Erratum January 21, 2005)
}}
| title = Beyond the Ivory Tower: The Scientific Consensus on Climate Change
In 2021, Krista Myers led a paper which surveyed 2780 Earth scientists. Depending on expertise, between 91% (all scientists) to 100% (climate scientists with high levels of expertise, 20+ papers published) agreed human activity is causing climate change. Among the total group of climate scientists, 98.7% agreed. The agreement was lowest among scientists who chose Economic Geology as one of their fields of research (84%).<ref name="Myers_2021" />
| journal = Science
| volume = 306
| issue = 5702
| pages = 1686
| doi = 10.1126/science.1103618
| url=http://www.sciencemag.org/cgi/reprint/306/5702/1686.pdf }} ()</ref> The essay concluded that there is a ] on the reality of ]. The author analyzed 928 ] of papers from refereed scientific journals between 1993 and 2003, listed with the keywords "global climate change". Oreskes divided the abstracts into six categories: explicit endorsement of the consensus position, evaluation of impacts, mitigation proposals, methods, ] analysis, and rejection of the consensus position. 75% of the abstracts were placed in the first three categories, thus either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, thus taking no position on current anthropogenic climate change; none of the abstracts disagreed with the consensus position, which the author found to be "remarkable". According to the report, "authors evaluating impacts, developing methods, or studying paleoclimatic change might believe that current climate change is natural. However, none of these papers argued that point."


Also in 2021, a team led by Mark Lynas had found 80,000 climate-related studies published between 2012 and 2020, and chose to analyse a random subset of 3000. Four of these were skeptical of the human cause of climate change, 845 were endorsing the human cause perspective at different levels, and 1869 were indifferent to the question. The authors estimated the proportion of papers not skeptical of the human cause as 99.85% (95% confidence limit 99.62%–99.96%). Excluding papers which took no position on the human cause led to an estimate of the proportion of consensus papers as 99.53% (95% confidence limit 98.80%–99.87%). They confirmed their numbers by explicitly looking for alternative hypotheses in the entire dataset, which resulted in 28 papers.<ref name="EnvRschLtrs_20211019" /><ref>{{cite web |last1=Ramanujan |first1=Krishna |title=More than 99.9% of studies agree: Humans caused climate change |url=https://news.cornell.edu/stories/2021/10/more-999-studies-agree-humans-caused-climate-change |website=Cornell Chronicle |publisher=Environmental Research Letters |access-date=20 October 2021}}</ref>
=== Bray and von Storch, 2003 ===
A survey was conducted in 2003 by Dennis Bray and ] <ref>http://w3g.gkss.de/G/mitarbeiter/bray/BrayGKSSsite/BrayGKSS/surveyframe.html</ref> <ref></ref> Bray's submission to '']'' on December 22, 2004 was rejected, but the survey's results were reported through non-scientific venues.<ref>, ''Matthews, Robert'' Telegraph, ] ]</ref><ref></ref> The survey received 530 responses from 27 different countries. One of the questions asked was ''"To what extent do you agree or disagree that climate change is mostly the result of anthropogenic causes?"'', with a value of 1 indicating strongly agree and a value of 7 indicating strongly disagree. The results showed a mean of 3.62, with 50 responses (9.4%) indicating "strongly agree" and 54 responses (9.7%) indicating "strongly disagree". The same survey indicates a 72% to 20% endorsement of the IPCC reports as accurate, and a 15% to 80% rejection of the thesis that ''"there is enough uncertainty about the phenomenon of global warming that there is no need for immediate policy decisions."''


== See also ==
The survey has been criticized on the grounds that it was performed on the web with no means to verify that the respondents were climate scientists or to prevent multiple submissions. The survey required entry of a username and password, but this information was circulated to a climate skeptics mailing list and elsewhere on the internet.<ref>""</ref><ref></ref>. Bray and von Storch have recently defended their results<ref> ''Hans von Storch and Dennis Bray''</ref> and accused skeptics of interpreting the results with bias.
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== References ==
=== Survey of U.S. state climatologists 1997 ===
{{reflist|refs=
In 1997, the conservative think tank ] surveyed America's 48 state climatologists on questions related to climate change<ref></ref>.
<ref name="amap">{{cite web |url=http://amap.no/acia/ |title=ACIA Display |publisher=Amap.no |access-date=30 July 2012 |archive-date=14 December 2010 |archive-url=https://web.archive.org/web/20101214135239/http://amap.no/acia/ |url-status=dead}}</ref>
Of the 36 respondents, 44% considered global warming to be a largely natural phenomenon, compared to 17% who considered warming to be largely man-made. The survey further found that 58% disagreed or somewhat disagreed with then-President Clinton's assertion that "the overwhelming balance of evidence and scientific opinion is that it is no longer a theory, but now fact, that global warming is for real". Eighty-nine percent agreed that "current science is unable to isolate and measure variations in global temperatures caused ONLY by man-made factors," and 61% said that historical data do not indicate "that fluctuations in global temperatures are attributable to human influences such as burning fossil fuels."


<ref name="Impacts of a Warming Arctic: Arctic Climate Impact Assessment New Scientific Consensus: Arctic Is Warming Rapidly">{{cite web |url=http://www.grida.no/polar/news/2427.aspx |title=Impacts of a Warming Arctic: Arctic Climate Impact Assessment New Scientific Consensus: Arctic Is Warming Rapidly|publisher=UNEP/GRID-Arendal|date=8 November 2004|access-date=20 January 2010}}</ref>
Sixty percent of the respondents said that reducing man-made CO2 emissions by 15% below 1990 levels would not prevent global temperatures from rising, and 86% said that reducing emissions to 1990 levels would not prevent rising temperatures. Thirty nine percent agreed and 33% disagreed that "evidence exists to suggest that the earth is headed for another glacial period,"<ref> Cooler Heads Coalition ] ]</ref> though the time scale for the next glacial period was not specified.


<ref name="inqua">{{cite web|url=http://www.inqua.org/files/iscc.pdf|title=INQUA Statement On Climate Change.}}</ref>
=== Bray and von Storch, 1996 ===
In 1996, Dennis Bray and Hans von Storch undertook a survey of climate scientists on attitudes towards global warming and related matters. The results were subsequently published in the ].<ref>{{cite journal | url=http://coast.gkss.de/staff/storch/pdf/bray_storch_1999.pdf | title=Climate Science: An Empirical Example of Postnormal Science | journal=Bulletin of the American Meteorological Society | last=Bray | first=Dennis | coauthors=] | date=1999 | accessdate=2007-09-04}}</ref> The paper addressed the views of climate scientists, with a response rate of 40% from a mail survey questionnaire to 1000 scientists in ], the ] and ]. Most of the scientists believed that global warming was occurring and appropriate policy action should be taken, but there was wide disagreement about the likely effects on society and almost all agreed that the predictive ability of currently existing models was limited.


<ref name="NASAC2007">{{cite web | url=http://www.interacademies.net/File.aspx?id=4825 | title=Joint statement by the Network of African Science Academies (NASAC) to the G8 on sustainability, energy efficiency and climate change | year=2007 | access-date=28 August 2012 | publisher=Network of African Science Academies | format=PDF | archive-date=9 June 2017 | archive-url=https://web.archive.org/web/20170609114053/http://www.interacademies.net/File.aspx?id=4825 | url-status=dead}}</ref>
The abstract says:


<ref name="nationalacademies21">{{cite web|url=http://nationalacademies.org/onpi/06072005.pdf|title=Joint Science Academies' Statement|access-date=2006-08-30|archive-date=2013-09-09|archive-url=https://web.archive.org/web/20130909022954/http://www.nationalacademies.org/onpi/06072005.pdf|url-status=dead}}</ref>
:The international consensus was, however, apparent regarding the utility of the knowledge to date: climate science has provided enough knowledge so that the initiation of abatement measures is warranted. However, consensus also existed regarding the current inability to explicitly specify detrimental effects that might result from climate change. This incompatibility between the state of knowledge and the calls for action suggests that, to some degree at least, scientific advice is a product of both scientific knowledge and normative judgment, suggesting a socioscientific construction of the climate change issue.


<ref name="Oreskes_consensus">{{cite book |title=Climate Change: What It Means for Us, Our Children, and Our Grandchildren |editor1-last=DiMento |editor1-first=Joseph F. C. |editor2-last=Doughman |editor2-first=Pamela M. |year=2007 |publisher=MIT Press |isbn=978-0-262-54193-0 |pages=65–66 |chapter=The Scientific Consensus on Climate Change: How Do We Know We're Not Wrong? |last=Oreskes |first=Naomi |chapter-url=https://books.google.com/books?id=PXJIqCkb7YIC&pg=PA65 |url=https://books.google.com/books?id=PXJIqCkb7YIC}}</ref>
The survey was extensive, and asked numerous questions on many aspects of climate science, model formulation, and utility, and science/public/policy interactions. To pick out some of the more vital topics, from the body of the paper:


<ref name="The Science of Climate Change">{{cite journal |date=18 May 2001 |title=The Science of Climate Change |journal=Science |volume=292 |issue=5520 |page=1261 |url=https://www.science.org/doi/10.1126/science.292.5520.1261 |publisher=Science Magazine|doi=10.1126/science.292.5520.1261 |pmid=11360966 |author1=Australian Academy of Science |author2=Royal Flemish Academy of Belgium for Sciences and the Arts |author3=Brazilian Academy of Sciences |author4=Royal Society of Canada |author5=Caribbean Academy of Sciences |author6=Chinese Academy of Sciences |author7=French Academy of Sciences |author8=German Academy of Natural Scientists Leopoldina |author9=Indian National Science Academy |author10=Indonesian Academy of Sciences |author11=Royal Irish Academy |author12=Accademia Nazionale dei Lincei (Italy) |author13=Academy of Sciences Malaysia |author14=Academy Council of the Royal Society of New Zealand |author15=Royal Swedish Academy of Sciences |author16=Turkish Academy of Sciences |author17=Royal Society (UK) }}</ref>
: The resulting questionnaire, consisting of 74 questions, was pre-tested in a German institution and after revisions, distributed to a total of 1,000 scientists in North America and Germany... The number of completed returns was as follows: USA 149, Canada 35, and Germany 228, a response rate of approximately 40%...


<ref name="The Structure of Scientific Opinion on Climate Change">{{cite web |url= http://ijpor.oxfordjournals.org/content/early/2011/10/27/ijpor.edr033.short|archive-url= https://web.archive.org/web/20130311113824/http://ijpor.oxfordjournals.org/content/early/2011/10/27/ijpor.edr033.short|url-status= dead|archive-date= 11 March 2013|title= The Structure of Scientific Opinion on Climate Change|author1=Stephen J. Farnsworth |author2=S. Robert Lichter |date= 27 October 2011|publisher= International Journal of Public Opinion Research |access-date= 2 December 2011}}</ref>
: ...With a value of 1 indicating the highest level of belief that predictions are possible and a value of 7 expressing the least faith in the predictive capabilities of the current state of climate science knowledge, the mean of the entire sample of 4.6 for the ability to make reasonable predictions of inter-annual variability tends to indicate that scientists feel that reasonable prediction is not yet a possibility... mean of 4.8 for reasonable predictions of 10 years... mean of 5.2 for periods of 100 years...


<ref name="Myers_2021">{{cite journal |last1=Myers |first1=Krista F. |last2= Doran |first2=Peter T. |last3=Cook |first3=John |last4=Kotcher |first4=John E. |last5=Myers |first5=Teresa A. |title=Consensus revisited: quantifying scientific agreement on climate change and climate expertise among Earth scientists 10 years later |journal= Environmental Research Letters |date=20 October 2021 |volume=16 |issue=10 |page=104030 |doi= 10.1088/1748-9326/ac2774 |bibcode= 2021ERL....16j4030M |s2cid= 239047650 |doi-access=free}}</ref>
: ...a response of a value of 1 indicates a strong level of agreement with the statement of certainty that global warming is already underway or will occur without modification to human behavior... the mean response for the entire sample was 3.3 indicating a slight tendency towards the position that global warming has indeed been detected and is underway.... Regarding global warming as being a possible future event, there is a higher expression of confidence as indicated by the mean of 2.6.


<ref name="EnvRschLtrs_20211019">{{cite journal |last1=Lynas |first1=Mark |last2=Houlton |first2=Benjamin Z. |last3=Perry |first3=Simon |title=Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature |journal=Environmental Research Letters |date=19 October 2021 |volume=16 |issue=11 |page= 114005 |doi=10.1088/1748-9326/ac2966 |bibcode= 2021ERL....16k4005L |s2cid= 239032360 |doi-access=free}}</ref>
=== Other older surveys of scientists ===
Note that the following surveys are over 15 years old. The state of climate science and the beliefs of climate scientists have changed radically since their time, as demonstrated by the reviews cited above.
*Global Environmental Change Report, 1990: GECR climate survey shows strong agreement on action, less so on warming. Global Environmental Change Report 2, No. 9, pp. 1-3
*, T.R., Mumpower, J.L., and Reagan-Cirincione, P. (1992). Scientists' opinions about global climate change: Summary of the results of a survey. NAEP (National Association of Environmental Professionals) Newsletter, 17(2), 6-7.
* A ] ] of 400 members of the ] and the ]{{Fact|date=February 2007}}
** ] states that the report said that 66% of the scientists said that human-induced global warming was occurring, with 10% disagreeing and the rest undecided. In a correction Gallup stated: "Most scientists involved in research in this area believe that human-induced global warming is occurring now."{{Fact|date=September 2007}}
** ] reported "53 percent do not believe warming has occurred, and another 30 percent are uncertain." (Washington Post, September 3, 1992)
** A 1993 publication by the ] states: "A Gallup poll conducted on February 13, 1992 of members of the American Geophysical Union and the American Meteorological Society - the two professional societies whose members are most likely to be involved in climate research - found that 18 percent thought some global warming had occurred, 33 percent said insufficient information existed to tell, and 49 percent believed no warming had taken place.<ref>http://downloads.heartland.org/2329do.pdf</ref>


<ref name="4thNationalClimateAssessment_20181123">{{cite journal |title=Climate Science Special Report / Fourth National Climate Assessment (NCA4), Volume I /Executive Summary / Highlights of the Findings of the U.S. Global Change Research Program Climate Science Special Report |url=https://science2017.globalchange.gov/chapter/executive-summary/ |website=globalchange.gov |publisher=U.S. Global Change Research Program |archive-url=https://web.archive.org/web/20190614150544/https://science2017.globalchange.gov/chapter/executive-summary/ |archive-date=14 June 2019 |date=23 November 2018 |doi=10.7930/J0DJ5CTG |url-status=live |last1=Wuebbles |first1=D.J. |last2=Fahey |first2=D.W. |last3=Hibbard |first3=K.A. |last4=Deangelo |first4=B. |last5=Doherty |first5=S. |last6=Hayhoe |first6=K. |last7=Horton |first7=R. |last8=Kossin |first8=J.P. |last9=Taylor |first9=P.C. |last10=Waple |first10=A.M. |last11=Yohe |first11=C.P. |pages=1–470 |doi-access=free}}</ref>
==See also==


<ref name="NDU1978">{{cite report |title=Climate Change to the Year 2000: A Survey of Expert Opinion |url=https://files.eric.ed.gov/fulltext/ED160394.pdf |date=February 1978}}</ref>
*]
*] , Sept. 21, 2005
*]
*] survey on climate change
*]
*]


<ref name="Stewart1992">{{cite report |last1=Stewart |first1=Thomas R. |last2=Mumpower |first2=Jeryl L. |last3=Reagan-Cirincione |first3=Patricia |url=https://www.albany.edu/cpr/stewart/Papers/StewartClimateSurvey-1992.pdf |title=Scientists' Agreement and Disagreement about Global Climate Change: Evidence from Surveys |date=April 1992}}</ref>
==References==
{{reflist|2}}


<ref name="BrayvonStorch1999">{{cite journal |last=Bray |first=Dennis |author2=Hans von Storch |author2-link=Hans von Storch |title=Climate Science: An Empirical Example of Postnormal Science |journal=Bulletin of the American Meteorological Society |year=1999 |url=https://ruby.fgcu.edu/courses/twimberley/envirophilo/postnormal.pdf |volume=80 |issue=3 |pages=439–455 |issn=1520-0477 |doi=10.1175/1520-0477(1999)080<0439:CSAEEO>2.0.CO;2 |bibcode=1999BAMS...80..439B |doi-access=free}}</ref>
==External links==
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* Freeview video provided by the Vega Science Trust.
*, National Academy of Sciences


<ref name="BrayvonStorch2003">{{cite journal |last1=Bray|first1=Dennis|last2=Storch|first2=Hans von |title=Climate Scientists' Perceptions of Climate Change Science.|journal=GKSS Report 11/2007|url=https://www.hereon.de/imperia/md/content/hzg/zentrale_einrichtungen/bibliothek/berichte/gkss_berichte_2007/gkss_2007_11.pdf}}</ref>
{{global warming}}


<ref name="John Cook 2013">{{cite journal|last=Cook|first=John |author2=Dana Nuccitelli |author3=Sarah A Green |author4=Mark Richardson |author5=Bärbel Winkler |author6=Rob Painting |author7=Robert Way |author8=Peter Jacobs |author9=Andrew Skuce|title=Quantifying the consensus on anthropogenic global warming in the scientific literature|journal=Environmental Research Letters|date=May 2013|volume=8|issue=2|pages=024024 |doi=10.1088/1748-9326/8/2/024024 |author-link=John Cook (Australian scientist)|bibcode = 2013ERL.....8b4024C |doi-access=free}}</ref>
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<ref name="Powell2017">{{Cite journal|last=Powell|first=James Lawrence|author-link=James L. Powell|date=24 May 2017|title=The Consensus on Anthropogenic Global Warming Matters|journal=Bulletin of Science, Technology & Society|language=en|volume=36|issue=3|pages=157–163|doi=10.1177/0270467617707079|s2cid=148618842}}</ref>
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<ref name="Powell2019">{{cite journal |last1=Powell |first1=James Lawrence |author-link=James L. Powell |date=20 November 2019 |title= Scientists Reach 100% Consensus on Anthropogenic Global Warming |url=https://journals.sagepub.com/doi/abs/10.1177/0270467619886266 |journal=Bulletin of Science, Technology & Society |volume=37 |issue=4 |pages= 183–184 |doi= 10.1177/0270467619886266 |s2cid= 213454806 |access-date=15 November 2020}}</ref>

<ref name="IPCC_AR6_WGI_SPM">IPCC, 2021: . In: . Cambridge University Press, Cambridge, United Kingdom and New York City, US, pp. 3–32, doi:10.1017/9781009157896.001.</ref>

<ref name="NCAR5_Ch2">Marvel, K., W. Su, R. Delgado, S. Aarons, A. Chatterjee, M.E. Garcia, Z. Hausfather, K. Hayhoe, D.A. Hence,
E.B. Jewett, A. Robel, D. Singh, A. Tripati, and R.S. Vose, 2023: . In: . Crimmins, A.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, B.C. Stewart, and T.K. Maycock, Eds. U.S.
Global Change Research Program, Washington, DC, USA. doi:10.7930/NCA5.2023.CH2</ref>
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{{Climate change}}

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Latest revision as of 20:28, 5 October 2024

Evaluation of climate change by the scientific community

Observed global warming: Global average temperature data from various scientific organizations show substantial agreement concerning the progress and extent of global warming: pairwise correlations for long-term datasets (1850+ and 1880+) exceed 99.1%.

There is a nearly unanimous scientific consensus that the Earth has been consistently warming since the start of the Industrial Revolution, that the rate of recent warming is largely unprecedented, and that this warming is mainly the result of a rapid increase in atmospheric carbon dioxide (CO2) caused by human activities. The human activities causing this warming include fossil fuel combustion, cement production, and land use changes such as deforestation, with a significant supporting role from the other greenhouse gases such as methane and nitrous oxide. This human role in climate change is considered "unequivocal" and "incontrovertible".

Nearly all actively publishing climate scientists say humans are causing climate change. Surveys of the scientific literature are another way to measure scientific consensus. A 2019 review of scientific papers found the consensus on the cause of climate change to be at 100%, and a 2021 study concluded that over 99% of scientific papers agree on the human cause of climate change. The small percentage of papers that disagreed with the consensus often contained errors or could not be replicated.

The evidence for global warming due to human influence has been recognized by the national science academies of all the major industrialized countries. In the scientific literature, there is a very strong consensus that global surface temperatures have increased in recent decades and that the trend is caused by human-induced emissions of greenhouse gases. No scientific body of national or international standing disagrees with this view. A few organizations with members in extractive industries hold non-committal positions, and some have tried to persuade the public that climate change is not happening, or if the climate is changing it is not because of human influence, attempting to sow doubt in the scientific consensus.

Existence of a scientific consensus

The public substantially underestimates the degree of scientific consensus that humans are causing climate change. Studies from 2019 to 2021 found scientific consensus to range from 98.7–100%.

Studies of the scientific opinion on climate change have been undertaken since the 1970s, and they have been establishing widespread consensus since the 1990s, with the level of agreement increasing over time. Individual scientists, universities, and laboratories contribute to the scientific opinion on climate change via their peer-reviewed publications, while the scientific bodies of national or international standing summarise the areas of collective agreement and relative certainty in synthesis reports.

Examples of such reports include or the 2004 Arctic Climate Impact Assessment from the International Arctic Science Committee and the governments of the Arctic Council, or the United States' National Climate Assessment, which has been released periodically since 2000 under the auspices of the United States Global Change Research Program. The fourth NCA, released in 2017, involved the efforts of thirteen federal agencies, led by the National Oceanic and Atmospheric Administration (NOAA), and around "1,000 people, including 300 leading scientists, roughly half from outside the government."

The Intergovernmental Panel on Climate Change (IPCC) had been formed by the United Nations in 1988, and it presents reports summarizing the strength and extent of consensus on climate change and its numerous aspects to the member states of the United Nations, with the major reports released at 5-to-7-year intervals starting from 1990.

Page counts of the six IPCC Assessment Reports (1990 to 2021)
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 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.

In 2001, science academies from 17 countries (Australia, Belgium, Brazil, Canada, China, France, Germany, India, Indonesia, Ireland, Italy, Malaysia, New Zealand, Sweden, Trinidad, Turkey and the United Kingdom made a joint statement endorsing the work of IPCC. They concurred that the temperatures are rising and will continue to rise due to human activities, and also stressed the importance of cutting greenhouse gas emissions, concluding that "Business as usual is no longer a viable option". It is also notable for being one of the first statements to explicitly use the term "consensus". In 2005, another joint statement from the science academies of major countries (Brazil, Canada, China, France, Germany, India, Italy, Japan, Russia, United Kingdom and the United States referred to the conclusions of the IPCC as "the international scientific consensus", and urged prompt action on both climate change mitigation and climate change adaptation. Elsewhere around the world, other organizations to have referred to the scientific consensus include Network of African Science Academies in 2007, and the International Union for Quaternary Research in 2008.

In 2013, a study which found that out of over 4,000 peer-reviewed papers on climate science published since 1990, 97% agree, explicitly or implicitly, that global warming is happening and is human-caused. Surveys of scientists' views on climate change – with a focus on human caused climate change – have been undertaken since the 1970s. A 2016 reanalysis confirmed that "the finding of 97% consensus in published climate research is robust and consistent with other surveys of climate scientists and peer-reviewed studies." A 2019 study found scientific consensus to be at 100%, and a 2021 study found that consensus exceeded 99%.

Consensus points

The warming influence (called radiative forcing) of long-lived atmospheric greenhouse gases has nearly doubled in 40 years.

The scientific consensus regarding causes and mechanisms of climate change, its effects and what should be done about it (climate action) is that:

  • It is "unequivocal" and "incontrovertible" that the greenhouse gas emissions from human activities have caused warming on land, in oceans and in the troposphere. There are no natural processes which can provide an alternate explanation.
  • The atmospheric levels of carbon dioxide are the highest they have been in at least 2 million years, if not 3.2 million years. The atmospheric levels of two other major greenhouse gases, methane and nitrous oxide, are the highest they have been in at least the past 800,000 years. The record of the past 800,000 years also shows that the increases in their concentrations seen since 1750 would take millennia to be caused by natural processes.
  • The decade of 2010s has been 1.1 °C (2.0 °F) warmer than the late 19th century, and the warmest since the start of a consistent instrumental temperature record. The warming of the past 50 years has occurred faster than any other warming over the past 2,000 years, if not longer.
  • Precipitation appears to have been increasing since 1950, but the rainfall patterns have also been shifting, and there is more evidence for increases in heavy precipitation which causes flash floods.
  • Global sea level has increased by 20–25 cm (8–10 in) since 1900, with half of that increase occurring since 1980. This sea level rise has been the fastest in "at least the last 3000 years", which is very likely to have been caused by human activity.
  • As the recent warming heats the ocean, its water expands in volume. This causes half of the recent sea level rise, with the rest due to the warming melting the ice sheets and glaciers.
  • While there have always been severe and extreme weather events (e.g. tropical cyclones, thunderstorms, tornados, droughts, heat waves, precipitation extremes), climate change has made many of them more severe, more frequent, or more likely to co-occur, in every part of the globe.
  • The dangers of extreme weather events will continue increasing unless there is a rapid decrease in greenhouse gas emissions needed to curb further warming.
  • Increased warming will lead to worse impacts.
  • The extent of human-caused emissions will be the main cause of future warming.

Statements by major scientific organizations about climate change

Main article: List of statements by major scientific organizations about climate change

Many of the major scientific organizations about climate change have issued formal statements of opinion. The vast majority of these statements concur with the IPCC view, some very few are non-committal, or dissent from it. The California Governor's Office website lists nearly 200 worldwide scientific organizations who hold the position that climate change has been caused by human action.

Surveys of scientists' views on climate change

See also: History of climate change science

1970s

The Fourth National Climate Assessment ("NCA4", USGCRP, 2017) includes charts illustrating how human factors, especially accumulation in the atmosphere of greenhouse gases, are the predominant cause of observed global warming. In the 1970s, these factors were less well-understood, and some scientists thought volcanic activity would have a stronger cooling effect than what we know now.

In 1978, the National Defense University of the United States had surveyed 24 experts about the near-term climate change and its effects on agriculture. The majority of respondents had expected some warming to occur between 1970 and 2000, and described human emissions of carbon dioxide as the primary cause, but there was a disagreement on the extent, and a few had thought that an increase in volcanic activity would offset carbon dioxide emissions by elevating atmospheric sulfate concentrations (which have a reflective effect, also associated with global dimming, and with some solar geoengineering proposals) and result in overall cooling. When NDU had combined their predictions, they estimated a 10% likelihood of large (~0.6 °C (1.1 °F)) cooling occurring by 2000, a 25% likelihood of smaller cooling around 0.15 °C (0.27 °F), a 30% likelihood of limited change, with around 0.1 °C (0.18 °F) warming, a 25% likelihood of "moderate" warming of ~0.4 °C (0.72 °F), and a 10% likelihood of large warming of around 1 °C (1.8 °F). Subsequently, about 0.5 °C (0.90 °F) had occurred between 1950 and 2000, with about 0.4 °C (0.72 °F) since 1970, largely matching the survey's "moderate global warming" scenario.

1980s

In 1989, David H. Slade had surveyed 21 climate scientists, of whom 17 had expressed "a strong belief" in "the reality of a significant climate change".

1990s

In March 1990, Cutter Information Corporation (now known as Cutter Consortium) sent questionnaires to 1500 researchers who were on the attendance lists of climate change conferences, and received 331 responses from 41 countries. The survey revealed widespread agreement that global warming is already happening, that it will result in negative impacts such as sea level rise, and that reducing carbon dioxide emissions and halting deforestation is an appropriate response to it. Only 1.9% of respondents predicted that there would be an overall cooling across the next 100 years. There was more disagreement on the strength of future warming: i.e. around 30% believed that there was a less than 50% chance that the warming would reach or exceed 2 °C (3.6 °F) over the next 100 years, while a larger fraction (almost 40%) thought such temperatures were at least 75% likely.

In 1991, the Center for Science, Technology, and Media sent a survey of 6 questions to around 4000 ocean and atmospheric scientists from 45 countries, and received 118 responses by January 1992, with 91% from North America. Out of those 118 scientists, 73 have either agreed or "strongly" agreed with the statement "There is little doubt among scientists that global mean temperature will increase", while 27 had disagreed and only 9 had "strongly disagreed", with the remaining 9 "neutral". 58 scientists had agreed that the effects of climate change are expected to be "substantial" by the scientific community as a whole, with 36 disagreeing and 21 staying neutral. Finally, when asked about the 1990 IPCC estimate of warming proceeding at 0.3 °F (0.17 °C) per decade throughout the 21st century under the business-as-usual climate change scenario, 13 (15%) expressed skepticism, 39 (44%) had emphasized uncertainty, and 37 (42%) had agreed. 52% thought the rate of warming would likely be lower, and 8% thought it would be higher. As of 2023, the rate of warming had been 0.2 °F (0.11 °C) or less.

In 1996, Dennis Bray and Hans von Storch, a pair of researchers at the Helmholtz Research Centre's Institute for Coastal Research, sent a questionnaire over mail to 1000 climate scientists in Germany, the United States and Canada. 40% responded, and the results subsequently published in the Bulletin of the American Meteorological Society in 1999. On a scale of 1 out of 7, where higher numbers indicated greater disagreement, "global warming is already underway" had a mean rating of 3.4, and "global warming will occur in the future" had an even greater agreement of 2.6 Surveyed scientists had less confidence in the accuracy of contemporary climate models, rating their ability to make "reasonable predictions" 10 years out at 4.8, and 5.2 for 100-year predictions: however, they consistently rejected the notion that there was too much uncertainty to justify taking immediate action, with a mean 5.6 out of 7 rating. In fact, they usually agreed there was substantial uncertainty about how strongly the impacts will affect society, and that many changes would likely be necessary to adapt.

2000–2004

In 2003, Bray and von Storch repeated their 1996 survey, using the same response structure with ratings on a 1–7 scale, and including all of the original questions. Further, new questions were added, which were devoted to climate change adaptation and media coverage of climate change. This second survey received 530 responses from 27 different countries, but it has been strongly criticized on the grounds that it was performed on the web with no means to verify that the respondents were climate scientists or to prevent multiple submissions. While the survey required entry of a username and password, its critics alleged that both were circulated to non-scientists, including to a climate change denial mailing list. Bray and von Storch defended their results, claiming that a statistical analysis with a Kolmogorov-Smirnov test and a Wald–Wolfowitz runs test revealed no significant irregularities.

In general, the second survey had demonstrated an increase in scientific confidence relative to the first. One of the greatest increases was for the statement "We can say for certain that global warming is a process already underway", where 1 represented strong agreement and 7 strong disagreement: the mean response went from 3.39 to 2.41. In response to the question, "To what extent do you agree or disagree that climate change is mostly the result of anthropogenic causes?", it went from 4.17 to 3.62. Notably, the percentage of respondents "strongly disagreeing" stayed the same, at 10%, and a similar percentage stayed neutral (14% in 1996 and 13% in 2003): yet, the overall split went from 41% agreement and 45% disagreement in 1996 to 56% agreement and 30% disagreement in 2003, as there was both a substantial increase in agreement and a decline percentage of those disagreeing less strongly. Similarly, there was a 72% to 20% split in favour of describing the IPCC reports as accurate, and a 15% to 80% rejection of the thesis that "there is enough uncertainty about the phenomenon of global warming that there is no need for immediate policy decisions."

In 2004, the geologist and historian of science Naomi Oreskes analyzed the abstracts of 928 scientific papers on "global climate change" published between 1993 and 2003. 75% had either explicitly expressed support for the scientific consensus on anthropogenic climate change, or had accepted it as a given and were focused on evaluating its impacts or proposing approaches for climate change mitigation, while the remaining 25% were devoted to methods of current climate change research or paleoclimate analysis. No abstract had explicitly rejected the scientific consensus.

2005–2009

A graphic representing the combined result of surveys taken throughout 2000s.

In 2007, Harris Interactive surveyed 489 randomly selected members of either the American Meteorological Society or the American Geophysical Union for the Statistical Assessment Service (STATS) at George Mason University, publishing the results in April 2008. 97% of the scientists surveyed agreed that global temperatures had increased during the past 100 years, and only 5% believed that human activity does not contribute to greenhouse warming. 84% said they personally believed human-induced warming was occurring, and 74% agreed that "currently available scientific evidence" substantiated its occurrence. 56% described the study of global climate change as a mature science and 39% as an emerging science. When asked about the likely severity of effects of climate change over the next 50–100 years, 41% said they could be described as catastrophic; 44% thought the effects would be moderately dangerous while about 13% thought there was relatively little danger.

The third Dennis Bray and Hans von Storch survey was also conducted in 2008, with the results published in 2010. It used the same methodology as their two previous surveys, with a similar number of sections and also asking to rate responses on a 1-to-7 scale (i.e. from 'not at all' to 'very much'), but it had also introduced web links with respondent-specific unique identifiers to eliminate multiple responses. 2058 climate scientists from 34 countries were surveyed, and a total of 373 responses were received (response rate of 18.2%).

To the question "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 67.1% said they very much agreed (7), 26.7% agreed to some large extent (6), 6.2% said to they agreed to some small extent (2–4), none said they did not agree at all. To the question "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?" the responses were 34.6% very much agree, 48.9% agreeing to a large extent, 15.1% to a small extent, and 1.35% not agreeing at all. Similarly, 34.6% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 27.6% agreed to a large extent, while only 1.1% did not agree at all.

At the same time, the respondents had strongly rejected the concept of intentionally presenting the most extreme possibilities in the hope of mobilizing the public, with around 73% disagreeing (1–3), 12.5% unsure and 14.5% agreeing in any way (5–7). Only 1.6% had agreed very much, while 27.2% did not agree at all, even as they overwhelmingly agreed (84% vs. 4%) that the scientists who do this are the most likely to be listened to by journalists. The respondents have generally expressed high confidence in the IPCC reports, with 63.5% agreeing that they estimated the impacts of temperature change exactly right (4 on the scale), and only 1.4% responding that they had strongly underestimated and 2.5% that they had strongly overestimated those impacts (1 and 7 on a scale.) On sea level rise, 51.4% thought the reports were exactly right, and only about 16% thought it was overestimated in any way (5–7), while the remaining third believed it was underestimated (1–3). Subsequent IPCC reports had been forced to regularly increase their estimates of future sea level rise, largely in response to newer research on the ice sheets of Greenland and Antarctica.

In 2009, Peter Doran and Maggie Kendall Zimmerman at University of Illinois at Chicago polled 10,257 earth scientists from various specialities and received replies from 3,146. 79 respondents were climatologists who had published over half of their peer-reviewed research on the subject of climate change, and 76 of them agreed that mean global temperatures had risen compared to pre-1800s levels, with 75 describing human activity as a significant factor. Among all respondents, 90% agreed that temperatures have risen compared to pre-1800 levels, and 82% agreed that humans significantly influence the global temperature. Economic geologists and meteorologists were among the biggest doubters, with only 47 percent and 64 percent, respectively, believing in significant human involvement. In summary, Doran and Zimmerman wrote:

It seems that the debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes.

2010–2014

A 2010 paper in the Proceedings of the National Academy of Sciences of the United States of America reviewed publication and citation data for 1,372 climate researchers, 908 of whom had authored 20 or more publications on climate, and found that

(i) 97–98% of the climate researchers most actively publishing in the field support the tenets of ACC (Anthropogenic Climate Change) outlined by the Intergovernmental Panel on Climate Change, and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.

In October 2011, researchers from George Mason University analyzed the results of a survey of 998 actively working scientists from the American Geophysical Union, the American Meteorological Society, or listed in the 23rd edition of American Men and Women of Science, 489 of whom had returned completed questionnaires. 97% of respondents had agreed that global temperatures have risen over the past century. 84% agreed that "human-induced greenhouse warming is now occurring," 5% disagreed, and 12% didn't know. When asked what they regard as "the likely effects of global climate change in the next 50 to 100 years," on a scale of 1 to 10, from Trivial to Catastrophic: 13% of respondents replied 1 to 3 (trivial/mild), 44% replied 4 to 7 (moderate), 41% replied 8 to 10 (severe/catastrophic), and 2% didn't know.

In 2012, James L. Powell, a former member of the National Science Board, analyzed published research on global warming and climate change between 1991 and 2012 and found that of the 13,950 articles in peer-reviewed journals, only 24 (<0.2%) rejected anthropogenic global warming. This was a follow-up to an analysis looking at 2,258 peer-reviewed articles published between November 2012 and December 2013, which revealed that only one of the 9,136 authors rejected anthropogenic global warming.

Dennis Bray and Hans von Storch had conducted their fourth survey in 2013, publishing its results the following year. 283 scientists had responded: 185 (65.4%) had been working in climate science for over 15 years, and only 19 (6.7%) had 0 to 5 years of experience. It had the same methodology as the third survey, ranking responses on a 1-to-7 scale and similar responses to the same questions: i.e., when asked, "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 74.7% said they very much agreed (7), 2.9% were "neutral" (4), and only 2.1% were 1–3 on the scale. To the question "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?", 43% had very much agreed, 28.5% agreeing to a large extent (6), 16.6% to a small extent (2–4), and 2.5% did not agree at all (1). 41.8% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 23.2% agreed to a large extent, while 3.5% did not agree at all. A new question asked respondents to attribute a percentage of recent warming to anthropogenic causes: 73.3% of scientists attributed 70–100%, while only 1.5% said there was zero human role.

In 2013, it had been quantified that the vast majority of published scientific literature had agreed with the human role in climate change since the 1990s.

In 2013, another scientist, John Cook, examined 11,944 abstracts from the peer-reviewed scientific literature from 1991 to 2011 that matched the topics 'global climate change' or 'global warming'. He and his co-authors found that, while 66.4% of them expressed no position on anthropogenic global warming (AGW), of those that did, 97.1% endorsed the consensus position that humans are contributing to global warming. They also invited authors to rate their own papers and found that, while 35.5% rated their paper as expressing no position on AGW (known to be expected in a consensus situation) 97.2% of the rest endorsed the consensus. In both cases the percentage of endorsements among papers expressing a position was marginally increasing over time. They concluded that the number of papers actually rejecting the consensus on AGW is a vanishingly small proportion of the published research, and that "the fundamental science of AGW is no longer controversial among the publishing science community and the remaining debate in the field has moved on to other topics."

In 2014, researchers from the Netherlands Environmental Assessment Agency surveyed 1,868 climate scientists. They found that, consistent with other research, the level of agreement on anthropogenic causation correlated with expertise – 90% of those surveyed with more than 10 peer-reviewed papers related to climate (just under half of survey respondents) explicitly agreed that greenhouse gases were the main cause of global warming. They included researchers on mitigation and adaptation in their surveys in addition to physical climate scientists, leading to a slightly lower level of consensus compared to previous studies.

2015–2019

The consensus on anthropogenic global warming among the peer-reviewed studies published between 1991 and 2015.

A 2016 study titled Learning from mistakes in climate research followed up on John Cook's 2013 paper by examining the quality of the 3% of peer-reviewed papers which had rejected the consensus view. They discovered that "replication reveals a number of methodological flaws, and a pattern of common mistakes emerges that is not visible when looking at single isolated cases". That same year, Cook's paper was criticized by Richard Tol, but strongly defended by a companion paper in the same volume.

The 5th International Survey of Climate Scientists by Dennis Bray and Hans von Storch took place over December 2015 and January 2016. Unlike the past surveys, the scientists were no longer questioned on their opinion of the IPCC, and there was much more focus on extreme event attribution. In other ways, it had replicated the methodology of the previous surveys, with most responses ranked on a 1-to-7 scale. There were over 600 complete responses: 291 (45.2%) had been working in climate science for over 15 years, while 79 (12.3%) had 0 to 5 years of experience. When asked "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 79.3% said they very much agreed (7), 1.2% were "neutral" (4), and only 2.1% were 1–3 on the scale. To the question "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?", 47.7% had very much agreed, 26% agreeing to a large extent (6), 9.8% to a small extent (2–4), and 1.9% did not agree at all (1). 46% had very much agreed that climate change "poses a very serious and dangerous threat to humanity" and 26% agreed to a large extent, while 2.2% did not agree at all. 75.8% said that the level of uncertainty in climate science had decreased since 1996, while 13.6% said it had increased. 75.7% said that the level of risk associated with climate change had increased considerably since 1996, while 5% said it had decreased.

In 2017, James L. Powell analyzed five surveys of the peer-reviewed literature from 1991 to 2015, and found that they amounted to a combined 54,195 articles, few of which had outright rejected anthropogenic climate change, resulting in an average consensus of 99.94%. In November 2019, his survey of over 11,600 peer-reviewed articles published in the first seven months of 2019 showed that the consensus had reached 100%.

2020s

Scientific consensus on causation: Academic studies of scientific agreement on human-caused global warming among climate experts (2010–2015) reflect that the level of consensus correlates with expertise in climate science. A 2019 study found scientific consensus to be at 100%, and a 2021 study concluded that consensus exceeded 99%. Another 2021 study found that 98.7% of climate experts indicated that the Earth is getting warmer mostly because of human activity.In a 2024 survey, 76.3% of responding IPCC lead authors and review editors projected at least 2.5 °C of global warming by 2100; only 5.79% forecast warming of 1.5 °C or less. Separately, then-current climate policies indicate the world will have warmed by about 2.7 °C.

In 2021, Krista Myers led a paper which surveyed 2780 Earth scientists. Depending on expertise, between 91% (all scientists) to 100% (climate scientists with high levels of expertise, 20+ papers published) agreed human activity is causing climate change. Among the total group of climate scientists, 98.7% agreed. The agreement was lowest among scientists who chose Economic Geology as one of their fields of research (84%).

Also in 2021, a team led by Mark Lynas had found 80,000 climate-related studies published between 2012 and 2020, and chose to analyse a random subset of 3000. Four of these were skeptical of the human cause of climate change, 845 were endorsing the human cause perspective at different levels, and 1869 were indifferent to the question. The authors estimated the proportion of papers not skeptical of the human cause as 99.85% (95% confidence limit 99.62%–99.96%). Excluding papers which took no position on the human cause led to an estimate of the proportion of consensus papers as 99.53% (95% confidence limit 98.80%–99.87%). They confirmed their numbers by explicitly looking for alternative hypotheses in the entire dataset, which resulted in 28 papers.

See also

References

  1. ^ IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change . Cambridge University Press, Cambridge, United Kingdom and New York City, US, pp. 3–32, doi:10.1017/9781009157896.001.
  2. ^ Marvel, K., W. Su, R. Delgado, S. Aarons, A. Chatterjee, M.E. Garcia, Z. Hausfather, K. Hayhoe, D.A. Hence, E.B. Jewett, A. Robel, D. Singh, A. Tripati, and R.S. Vose, 2023: Chapter 2. Climate trends. In: Fifth National Climate Assessment. Crimmins, A.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, B.C. Stewart, and T.K. Maycock, Eds. U.S. Global Change Research Program, Washington, DC, USA. doi:10.7930/NCA5.2023.CH2
  3. "Total radiative forcing is positive and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750." and "From 1750 to 2011, CO2 emissions from fossil fuel combustion and cement production have released 375 GtC to the atmosphere, while deforestation and other land-use change are estimated to have released 180 GtC." In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change . Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
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