View source for Earth:Scientific opinion on climate change


[[File:Scientific consensus - Earth's climate is warming (Temperature Anomaly ℃).png|thumb|450px|<small>From NASA’s Global Climate Change website - https://climate.nasa.gov/</small>]]

'''Scientific opinion on climate change''' is a judgment of scientists regarding the degree to which [[Earth:Global warming|global warming]] is occurring, its likely causes, and its probable consequences. 

A related&mdash;but not identical&mdash;term, "scientific '''consensus''' on climate change," is the ''prevailing'' view on climate change within the scientific community. The consensus is that:
* Earth's climate has warmed significantly since the late 1800s, 
* Human activities (primarily [[Chemistry:Greenhouse gas|greenhouse gas]] emissions) are the primary cause, 
* Continuing emissions will increase the likelihood and severity of [[Biology:Effects of global warming|global effects]], and that
* We could manage future climate change impacts through intense efforts at [[Earth:Climate change mitigation|reducing further warming]] while [[Earth:Climate change adaptation|preparing for any unavoidable]] climate changes.


==Scientific consensus==
Several studies of the consensus have been undertaken.<ref name=ConsensusOnConsensus2016>{{Cite journal |last=Cook|first=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|url=http://stacks.iop.org/1748-9326/11/i=4/a=048002|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}}</ref> Among the most-cited is a 2013 study of nearly 12,000 abstracts of peer-reviewed papers on climate science published since 1990, of which just over 4,000 papers expressed an opinion on the cause of recent global warming. Of these, 97% agree, explicitly or implicitly, that global warming is happening and is human-caused.<ref>Cook, John, ''et al.'' "[http://iopscience.iop.org/article/10.1088/1748-9326/8/2/024024 Quantifying the consensus on anthropogenic global warming in the scientific literature]." ''IOP Science,'' 30 Oct. 2013. Retrieved 28 June 2018.</ref><ref>{{cite web|title=Scientific and Public Perspective on climate change|url=http://climatecommunication.yale.edu/publications/scientific-and-public-perspectives-on-climate-change/|website=Yale Program on Climate Communication}}</ref> It is "extremely likely"<ref name="USGCRP4volI">Wuebbles, D.J., et al., 2017: Executive summary. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I [Wuebbles, D.J., D.W. Fahey, K.A. Hibbard, D.J. Dokken, B.C. Stewart, and T.K. Maycock (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, pp. 12-34, [https://science2017.globalchange.gov/chapter/executive-summary/ doi:10.7930/J0DJ5CTG].</ref> that this warming arises from "... human activities, especially emissions of [[Chemistry:Greenhouse gas|greenhouse gas]]es ..."<ref name="USGCRP4volI" /> in the [[Earth:Atmosphere of Earth|atmosphere]].<ref>{{Cite news|url=https://climate.nasa.gov/scientific-consensus/|title=Scientific consensus: Earth's climate is warming|work=Climate Change: Vital Signs of the Planet|publisher=National Aeronautics and Space Administration (NASA)|access-date=2018-08-18|quote=Multiple studies published in peer-reviewed scientific journals1 show that 97 percent or more of actively publishing climate scientists agree: Climate-warming trends over the past century are extremely likely due to human activities. In addition, most of the leading scientific organizations worldwide have issued public statements endorsing this position.}}</ref> Natural change alone would have had a slight cooling effect rather than a warming effect.<ref name="AR4-warming-unequivocal" /><ref name="ipcc">{{citation
 | author = IPCC
 | title = Detection and Attribution of Climate Change
 | chapter = Summary for Policymakers
 | chapter-url = http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf
 | quote = «It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century» (page 17) and «In this Summary for Policymakers, the following terms have been used to indicate the assessed likelihood of an outcome or a result: (...) extremely likely: 95–100%» (page 2).
 }}, in {{Harvnb|IPCC AR5 WG1|2013}}.</ref><ref name="ipcc1" /><ref name="AmericasClimateChoices-2010-SciPanel" />

This scientific opinion is expressed in [[Systematic review|synthesis reports]], by scientific bodies of national or international standing, and by [[Earth:Surveys of scientists' views on climate change|surveys of opinion among climate scientists]]. Individual scientists, universities, and laboratories contribute to the overall scientific opinion via their peer-reviewed [[Scientific journal|publications]], and the areas of collective agreement and relative certainty are summarised in these respected reports and surveys.<ref name="Oreskes_consensus"/>
The [[Organization:Intergovernmental Panel on Climate Change|IPCC]]'s Fifth Assessment Report (AR5) was completed in 2014.<ref name="IPCC_AR5_Synth">IPCC, 2014: [http://www.ipcc.ch/report/ar5/syr/ Climate Change 2014: Synthesis Report]. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.</ref> Its conclusions are summarized below:
* "Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia".<ref>
IPCC (11 November 2013): B. Observed Changes in the Climate System, in: [https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf Summary for Policymakers (finalized version)], in: {{harvnb|IPCC AR5 WG1|2013|p=2}}
</ref>
* "Atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years".<ref> IPCC (11 November 2013): B.5 Carbon and Other Biogeochemical Cycles, in: [https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf Summary for Policymakers (finalized version)], in: {{harvnb|IPCC AR5 WG1|2013|p=9}}
</ref>
* Human influence on the climate system is clear.<ref name="IPCC AR5 attribution">
IPCC (11 November 2013): D. Understanding the Climate System and its Recent Changes, in: [https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf Summary for Policymakers (finalized version)], in: {{harvnb|IPCC AR5 WG1|2013|p=13}}
</ref> It is extremely likely (95-100% probability)<ref>
IPCC (11 November 2013): Footnote 2, in: [https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf Summary for Policymakers (finalized version)], in: {{harvnb|IPCC AR5 WG1|2013|p=2}}</ref> that human influence was the dominant cause of global warming between 1951-2010.<ref name="IPCC AR5 attribution"/>
* "Increasing magnitudes of [global] warming increase the likelihood of severe, pervasive, and irreversible impacts"<ref name="Summary for Policymakers">[http://ipcc-wg2.gov/AR5/images/uploads/WG2AR5_SPM_FINAL.pdf Summary for Policymakers], p.14 (archived [https://web.archive.org/web/20140625070215/http://ipcc-wg2.gov/AR5/images/uploads/WG2AR5_SPM_FINAL.pdf 25 June 2014)], in {{harvnb|IPCC AR5 WG2 A|2014}}</ref>
* "A first step towards adaptation to future climate change is reducing vulnerability and exposure to present climate variability"<ref>
[http://ipcc-wg2.gov/AR5/images/uploads/WG2AR5_SPM_FINAL.pdf Summary for Policymakers], p.23 (archived [https://web.archive.org/web/20140625070215/http://ipcc-wg2.gov/AR5/images/uploads/WG2AR5_SPM_FINAL.pdf 25 June 2014)], in {{harvnb|IPCC AR5 WG2 A|2014}}</ref>
* "The overall risks of climate change impacts can be reduced by limiting the rate and magnitude of climate change"<ref name="Summary for Policymakers"/>
* Without new [[Earth:Individual and political action on climate change|policies to mitigate climate change]], projections suggest an increase in global mean temperature in 2100 of 3.7 to 4.8&nbsp;°C, relative to pre-industrial levels ([[Median|median]] values; the range is 2.5 to 7.8&nbsp;°C including climate uncertainty).<ref>
SPM.3 Trends in stocks and flows of greenhouse gases and their drivers, in: [http://templatelab.com/ipcc_wg3_ar5_summary-for-policymakers_approved/ Summary for Policymakers], p.8 (archived [https://web.archive.org/web/20140702014732/http://report.mitigation2014.org/spm/ipcc_wg3_ar5_summary-for-policymakers_approved.pdf 2 July 2014)], in {{harvnb|IPCC AR5 WG3|2014}}
</ref>
* The current trajectory of global greenhouse gas emissions is not consistent with limiting global warming to below 1.5 or 2&nbsp;°C, relative to pre-industrial levels.<ref>
Victor, D., ''et al.'', Executive summary, in: [http://report.mitigation2014.org/drafts/final-draft-postplenary/ipcc_wg3_ar5_final-draft_postplenary_chapter1.pdf Chapter 1: Introductory Chapter], p.4 (archived [https://web.archive.org/web/20140703063821/http://report.mitigation2014.org/drafts/final-draft-postplenary/ipcc_wg3_ar5_final-draft_postplenary_chapter1.pdf 3 July 2014)], in {{harvnb|IPCC AR5 WG3|2014}}
</ref> Pledges made as part of the Cancún Agreements are broadly consistent with cost-effective scenarios that give a "likely" chance (66-100% probability) of limiting global warming (in 2100) to below 3&nbsp;°C, relative to pre-industrial levels.<ref>
SPM.4.1 Long‐term mitigation pathways, in: [http://report.mitigation2014.org/spm/ipcc_wg3_ar5_summary-for-policymakers_approved.pdf Summary for Policymakers], p.15 (archived [https://web.archive.org/web/20140702014732/http://report.mitigation2014.org/spm/ipcc_wg3_ar5_summary-for-policymakers_approved.pdf 2 July 2014)], in {{harvnb|IPCC AR5 WG3|2014}}
</ref>
[[File:Columbia Glacier in Alaska.jpg|alt=The Columbia Glacier in Alaska - 1986 vs 2011|left|thumb|The Columbia Glacier in Alaska, one of many vanishing around the world. Glacier retreat is one of the most direct and understandable effects of climate change.]]
National and international science academies and [[Organization:Learned society|scientific societies]] have assessed current scientific opinion on [[Earth:Global warming|global warming]]. These assessments are generally consistent with the conclusions of the [[Organization:Intergovernmental Panel on Climate Change|Intergovernmental Panel on Climate Change]].

Some scientific bodies have recommended specific policies to governments, and science can play a role in informing an effective response to climate change. Policy decisions, however, may require value judgements and so are not included in the scientific opinion.<ref name="tar value judgements"/><ref name="NRC on policy"/>

No scientific body of national or international standing maintains a formal opinion dissenting from any of these main points. The last national or international scientific body to drop dissent was the [[Organization:American Association of Petroleum Geologists|American Association of Petroleum Geologists]],<ref name=AQAonAAPG/> which in 2007<ref name="aapg19"/> updated its statement to its current non-committal position.<ref name="Oreskes07p68"/> Some other organizations, primarily those focusing on geology, also hold non-committal positions.

== Synthesis reports ==
Synthesis reports are assessments of scientific literature that compile the results of a range of stand-alone studies in order to achieve a broad level of understanding, or to describe the state of knowledge of a given subject.<ref name="Integration and Synthesis: Assessing Climate Change Impacts in Northern Canada"/>

=== Intergovernmental Panel on Climate Change (IPCC) 2014 ===
{{main article|Organization:Intergovernmental Panel on Climate Change|Earth:IPCC Fifth Assessment Report}}

The IPCC Fifth Assessment Report followed the same general format as the Fourth Assessment Report, with three Working Group reports and a Synthesis report.<ref name="IPCC_AR5_Synth"/> The Working Group I report (WG1) was published in September 2013.<ref name="IPCC_AR5_Synth"/> The report's ''Summary for Policymakers'' stated that warming of the climate system is 'unequivocal' with changes unprecedented over decades to millennia, including warming of the atmosphere and oceans, [[Earth:Retreat of glaciers since 1850|loss of snow and ice]], and [[Earth:Sea level rise|sea level rise]]. [[Chemistry:Greenhouse gas|Greenhouse gas]] emissions, driven largely by economic and population growth, have led to greenhouse gas concentrations that are unprecedented in at least the last 800,000 years. These, together with other anthropogenic drivers, are "extremely likely" to have been the dominant cause of the observed global warming since the mid-20th century.<ref name=IPCC-AR5-SYN>{{cite web|title=Climate Change 2014 Synthesis Report Summary for Policymakers|url=http://www.ipcc.ch/pdf/assessment-report/ar5/syr/AR5_SYR_FINAL_SPM.pdf|publisher=IPCC|accessdate=1 August 2015}}</ref>

It said that
{{quote|Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks.<ref name=IPCC-AR5-SYN/>}}

Reporting on the publication of the report, ''{{wipe|The Guardian}}'' said that
{{quote|In the end it all boils down to risk management. The stronger our efforts to reduce greenhouse gas emissions, the lower the risk of extreme climate impacts. The higher our emissions, the larger climate changes we'll face, which also means more expensive adaptation, more species extinctions, more food and water insecurities, more income losses, more conflicts, and so forth.<ref>{{cite news|last1=Nuccitelli|first1=Dana|title=IPCC report warns of future climate change risks, but is spun by contrarians|url=https://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/mar/31/ipcc-warns-climate-change-risks|accessdate=1 August 2015|publisher=The Guardian|date=31 March 2014}}</ref>}}

''{{wipe|The New York Times}}'' reported that
{{quote|In Washington, President Obama's science adviser, [[Biography:John Holdren|John P. Holdren]], cited increased scientific confidence "that the kinds of harm already being experienced from climate change will continue to worsen unless and until comprehensive and vigorous action to reduce emissions is undertaken worldwide."<ref name=NYTimes-AR5>{{cite news|title=U.N. Climate Panel Endorses Ceiling on Global Emissions|url=https://www.nytimes.com/2013/09/28/science/global-climate-change-report.html|accessdate=1 August 2015|publisher=The New York Times|date=27 September 2013}}</ref>}}
It went on to say that Ban Ki-moon, the {{wipe|United Nations}} secretary general, had declared his intention to call a meeting of heads of state in 2014 to develop such a treaty. The last such meeting, in Copenhagen in 2009, the NY Times reported, had ended in disarray.<ref name=NYTimes-AR5/>

=== Intergovernmental Panel on Climate Change (IPCC) 2007 ===
In February 2007, the IPCC released a summary of the forthcoming [[Earth:IPCC Fourth Assessment Report|Fourth Assessment Report]]. According to this summary, the Fourth Assessment Report found that human actions are "very likely" the cause of global warming, meaning a 90% or greater probability. Global warming in this case was indicated by an increase of 0.75 degrees in average global temperatures over the last 100 years.<ref name="Warming 'very likely' human-made"/>

The [[Earth:IPCC Fourth Assessment Report|IPCC Fourth Assessment Report]] stated that:
* Warming of the climate system is unequivocal, as evidenced by increases in global average air and ocean [[Earth:Instrumental temperature record|temperatures]], the widespread melting of [[Physics:Snow|snow]] and [[Earth:Ice|ice]], and rising global average sea level.<ref>{{citation|title=1. Observed changes in climate and their effects|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms1.html|chapter=Summary for Policymakers|chapter-url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spm.html}}, in {{harvnb|IPCC AR4 SYR|2007}}
</ref>
* Most of the global warming since the mid-20th century is very likely due to [[Earth:Attribution of recent climate change|human activities]].<ref>{{citation|title=2. Causes of change|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms2.html|chapter=Summary for Policymakers|chapter-url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spm.html}}, in {{harvnb|IPCC AR4 SYR|2007}}
</ref>[[File:NASA Global Temperature change from 1880 to 2013.webm|alt=Color-coded map displaying a progression of changing global surface temperatures 1880 through 2013.|right|thumb|This color-coded map displays a progression of changing global surface temperatures anomalies from 1880 through 2013. Higher than normal temperatures are shown in red and lower than normal temperatures are shown in blue.]]
* Benefits and costs of climate change for [human] society will vary widely by location and scale.<ref name="parry social impacts">{{citation|title=Industry, settlement and society, in: Box TS.5. The main projected impacts for systems and sectors|url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/tssts-4-1.html|author=Parry, M.L.|chapter=Technical summary|chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ts.html|display-authors=0}}, in {{harvnb|IPCC AR4 WG2|2007}}
</ref> Some of the effects in [[Earth:Temperate climate|temperate]] and polar regions will be positive and others elsewhere will be negative.<ref name="parry social impacts" /> Overall, net effects are more likely to be strongly negative with larger or more rapid warming.<ref name="parry social impacts" />
* The range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time.<ref>{{citation|title=Magnitudes of impact|url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/spmsspm-c-15-magnitudes-of.html|author=IPCC|chapter=Summary for Policymakers|chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/spm.html}}, in {{harvnb|IPCC AR4 WG2|2007}}
</ref>
* The resilience of many [[Earth:Climate change and ecosystems|ecosystems]] is likely to be exceeded this century by an unprecedented combination of climate change, associated disturbances (e.g. [[Earth:Flood|flood]]ing, [[Earth:Drought|drought]], [[Biology:Wildfire|wildfire]], [[Biology:Insect|insect]]s, [[Biology:Ocean acidification|ocean acidification]]) and other [[Global change|global change]] drivers (e.g. land-use change, pollution, fragmentation of natural systems, [[Earth:Overexploitation|over-exploitation]] of resources).<ref>{{citation|title=Ecosystems, in: Sec 3.3.1 Impacts on systems and sectors|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/mains3-3-1.html|chapter=Synthesis report|chapter-url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spm.html}}, in {{harvnb|IPCC AR4 SYR|2007}}
</ref>

''The New York Times'' reported that "the leading international network of climate scientists has concluded for the first time that global warming is 'unequivocal' and that human activity is the main driver, 'very likely' causing most of the rise in temperatures since 1950".<ref name="rosenthal"/>

A retired journalist for ''The New York Times'', William K. Stevens wrote: "The Intergovernmental Panel on Climate Change said the likelihood was 90 percent to 99 percent that emissions of heat-trapping greenhouse gases like carbon dioxide, spewed from tailpipes and smokestacks, were the dominant cause of the observed warming of the last 50 years. In the panel's parlance, this level of certainty is labeled 'very likely'. Only rarely does scientific odds-making provide a more definite answer than that, at least in this branch of science, and it describes the endpoint, so far, of a progression.".<ref name="On the Climate Change Beat, Doubt Gives Way to Certainty"/>

The Associated Press summarized the position on sea level rise:
{{quote|On sea levels, the report projects rises of 7 to 23 inches by the end of the century. An additional 3.9 to 7.8 inches are possible if recent, surprising melting of polar ice sheets continues.<ref name="foxnews"/>}}

=== U.S. Global Change Research Program ===

:''Formerly: Climate Change Science Program''

The [[Organization:U.S. Global Change Research Program|U.S. Global Change Research Program]] reported in June 2009<ref name="globalchange"/> that:

{{quote|Observations show that warming of the climate is unequivocal. The global warming observed over the past 50 years is due primarily to human-induced emissions of heat-trapping gases. These emissions come mainly from the burning of fossil fuels (coal, oil, and gas), with important contributions from the clearing of forests, agricultural practices, and other activities.}}

The report, which is about the effects that climate change is having in the United States, also says:

{{quote|Climate-related changes have already been observed globally and in the United States. These include increases in air and water temperatures, reduced frost days, increased frequency and intensity of heavy downpours, a rise in sea level, and reduced snow cover, glaciers, permafrost, and sea ice. A longer ice-free period on lakes and rivers, lengthening of the growing season, and increased [[Physics:Water vapor|water vapor]] in the atmosphere have also been observed. Over the past 30 years, temperatures have risen faster in winter than in any other season, with average winter temperatures in the Midwest and northern Great Plains increasing more than {{convert|7|F-change|C-change}}. Some of the changes have been faster than previous assessments had suggested.}}

=== Arctic Climate Impact Assessment ===
In 2004, the intergovernmental [[Organization:Arctic Council|Arctic Council]] and the non-governmental [[Organization:International Arctic Science Committee|International Arctic Science Committee]] released the synthesis report of the [[Earth:Arctic Climate Impact Assessment|Arctic Climate Impact Assessment]]:<ref name="Impacts of a Warming Arctic: Arctic Climate Impact Assessment New Scientific Consensus: Arctic Is Warming Rapidly"/>

{{quote|Climate conditions in the past provide evidence that rising atmospheric carbon dioxide levels are associated with rising global temperatures. Human activities, primarily the burning of fossil fuels (coal, oil, and natural gas), and secondarily the clearing of land, have increased the concentration of carbon dioxide, methane, and other heat-trapping ("greenhouse") gases in the atmosphere...There is international scientific consensus that most of the warming observed over the last 50 years is attributable to human activities.<ref name="amap"/>}}

== Policy ==

There is an extensive discussion in the [[Scientific literature|scientific literature]] on what policies might be effective in responding to climate change.<ref name="ar4 policy assessment">The literature has been assessed by the IPCC, e.g., see:
* {{citation
 | title=Ch 17: Assessment of Adaptation Practices, Options, Constraints and Capacity
 | url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch17.html
 | author=Adger, W.N. |display-authors=0
}}, in {{harvnb|IPCC AR4 WG2|2007}}
* {{citation
 | title=Technical summary
 | url=http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ts.html
 | author=Barker, T. |display-authors=0
}}, in {{harvnb|IPCC AR4 WG3|2007}}
</ref> Some scientific bodies have recommended specific policies to governments (refer to the later sections of the article).<ref name="nationalacademies6"/> The [[Natural science|natural]] and [[Social:Social science|social science]]s can play a role in informing an effective response to climate change.<ref name="tar value judgements">
{{citation
 | title=1.1
 | url=http://www.grida.no/climate/ipcc_tar/vol4/english/017.htm
 | chapter=Question 1
}}, in {{harvnb|IPCC TAR SYR|2001|p=38}}
</ref> However, policy decisions may require value judgements.<ref name="tar value judgements"/> For example, the US National Research Council has commented:<ref name="NRC on policy">
[http://www.nap.edu/openbook.php?record_id=10139&page=4 Summary], in {{harvnb|US NRC|2001|p=4}}
</ref><blockquote>The question of whether there exists a "safe" level of concentration of greenhouse gases cannot be answered directly because it would require a value judgment of what constitutes an acceptable risk to human welfare and ecosystems in various parts of the world, as well as a more quantitative assessment of the risks and costs associated with the various impacts of global warming. In general, however, risk increases with increases in both the rate and the magnitude of climate change.</blockquote>

This article mostly focuses on the views of natural scientists. However, social scientists,<ref name="ar4 policy assessment"/> medical experts,<ref>
{{citation
 | title=Doha Declaration on Climate, Health and Wellbeing
 | url=http://dohadeclaration.weebly.com/
}}. This statement has been signed by numerous medical organizations, including the [[Organization:World Medical Association|World Medical Association]].
</ref> engineers<ref name="ar4 policy assessment"/> and philosophers<ref>
{{citation
 | title=The Ethics of Global Climate Change
 | date=March 2011
 | publisher=Cambridge University Press
 | url=http://www.cambridge.org/gb/knowledge/isbn/item5744232/?site_locale=en_GB
 | isbn=9781107000698
 | editor=Arnold, D.G.
}}
</ref> have also commented on climate change science and policies. Climate change policy is discussed in several articles: [[Earth:Climate change mitigation|climate change mitigation]], [[Earth:Climate change adaptation|climate change adaptation]], [[Earth:Climate engineering|climate engineering]], [[Earth:Politics of global warming|politics of global warming]], [[Earth:Climate ethics|climate ethics]], and [[Earth:Economics of global warming|economics of global warming]].

== Statements by scientific organizations of national or international standing ==
This is a list of scientific bodies of national or international standing, that have issued formal statements of opinion, classifies those organizations according to whether they concur with the IPCC view, are non-committal, or dissent from it. The California Governor's Office website lists nearly 200 worldwide scientific organizations hold the position that climate change has been caused by human action.<ref>{{cite web |url=https://www.opr.ca.gov/s_listoforganizations.php |title=Archived copy |accessdate=2017-08-07 |deadurl=yes |archiveurl=https://web.archive.org/web/20170807111205/https://www.opr.ca.gov/s_listoforganizations.php |archivedate=2017-08-07 |df= }}</ref>

=== Concurring ===

==== Academies of science (general science) ====
Since 2001, 34 national science academies, three regional academies, and both the international InterAcademy Council and International Council of Academies of Engineering and Technological Sciences have made formal declarations confirming human induced global warming and urging nations to reduce emissions of greenhouse gases. The 34 national science academy statements include 33 who have signed joint science academy statements and one individual declaration by the Polish Academy of Sciences in 2007.

===== Joint national science academy statements =====
* 2001 Following the publication of the [[Earth:IPCC Third Assessment Report|IPCC Third Assessment Report]], seventeen national science academies issued a joint statement, entitled "The Science of Climate Change", explicitly acknowledging the IPCC position as representing the scientific consensus on climate change science. The statement, printed in an editorial in the journal ''Science'' on May 18, 2001,<ref name="Editorial: The Science of Climate Change"/> was signed by the science academies of Australia, Belgium, Brazil, Canada, the Caribbean, China, France, Germany, India, Indonesia, Ireland, Italy, Malaysia, New Zealand, Sweden, Turkey, and the United Kingdom.<ref name="The Science of Climate Change"/>
* 2005 The national science academies of the [[Organization:G8|G8]] nations, plus Brazil, China and India, 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, and explicitly endorsed the IPCC consensus. The eleven signatories were the science academies of Brazil, Canada, China, France, Germany, India, Italy, Japan, Russia, the United Kingdom, and the United States.<ref name="nationalacademies"/>
* 2007 In preparation for the 33rd G8 summit, the national science academies of the [[Organization:G8+5|G8+5]] 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 [[Earth:IPCC Fourth Assessment Report|IPCC Fourth Assessment Report]], the declaration 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 [[Astronomy:Earth|Earth]] unless counter-measures are taken." The thirteen signatories were the national science academies of Brazil, Canada, China, France, Germany, Italy, India, Japan, Mexico, Russia, South Africa, the United Kingdom, and the United States.<ref name="pik-potsdam"/>
* 2007 In preparation for the 33rd G8 summit, the Network of African Science Academies submitted a joint "statement on sustainability, energy efficiency, and climate change" : {{quote|A consensus, based on current evidence, now exists within the global scientific community that human activities are the main source of climate change and that the burning of fossil fuels is largely responsible for driving this change. The IPCC should be congratulated for the contribution it has made to public understanding of the nexus that exists between energy, climate and sustainability. | The thirteen signatories were the science academies of Cameroon, Ghana, Kenya, {{wipe|Madagascar}}, Nigeria, Senegal, {{wipe|South Africa}}, Sudan, Tanzania, Uganda, Zambia, Zimbabwe, as well as the African Academy of Sciences | <ref name="autogenerated1"/>}}
* 2008 In preparation for the 34th G8 summit, the national science academies of the G8+5 nations issued a declaration reiterating the position of the 2005 joint science academies’ statement, and reaffirming "that climate change is happening and that anthropogenic warming is influencing many physical and biological systems." Among other actions, the declaration urges all nations to "(t)ake appropriate economic and policy measures to accelerate transition to a low carbon society and to encourage and effect changes in individual and national behaviour." The thirteen signatories were the same national science academies that issued the 2007 joint statement.<ref name="nationalacademies5"/>
* 2009 In advance of the UNFCCC negotiations to be held in [[Place:Copenhagen|Copenhagen]] in December 2009, the national science academies of the G8+5 nations issued a joint statement declaring, "Climate change and sustainable energy supply are crucial challenges for the future of humanity. It is essential that world leaders agree on the emission reductions needed to combat negative consequences of anthropogenic climate change". The statement references the IPCC's Fourth Assessment of 2007, and asserts that "climate change is happening even faster than previously estimated; global {{CO2}} emissions since 2000 have been higher than even the highest predictions, Arctic sea ice has been melting at rates much faster than predicted, and the rise in the sea level has become more rapid." The thirteen signatories were the same national science academies that issued the 2007 and 2008 joint statements.<ref name="nationalacademies6"/>

===== Polish Academy of Sciences =====
In December 2007, the General Assembly of the Polish Academy of Sciences (Polska Akademia Nauk), which has not been a signatory to joint national science academy statements issued a declaration endorsing the IPCC conclusions, and stating:
{{quote|it is the duty of Polish science and the national government to, in a thoughtful, organized and active manner, become involved in realisation of these ideas.

Problems of global warming, climate change, and their various negative impacts on human life and on the functioning of entire societies are one of the most dramatic challenges of modern times.

PAS General Assembly calls on the national scientific communities and the national government to actively support Polish participation in this important endeavor.<ref name="Stanowisko Zgromadzenia Ogólnego PAN z dnia 13 grudnia 2007 r"/>}}

===== Additional national science academy and society statements =====
* American Association for the Advancement of Science as the world's largest general scientific society, adopted an official statement on climate change in 2006: {{quote|The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society....The pace of change and the evidence of harm have increased markedly over the last five years. The time to control greenhouse gas emissions is now.<ref name="aaas board"/>}}
* Federation of Australian Scientific and Technological Societies in 2008 published ''FASTS Statement on Climate Change''<ref name="FASTS Statement on Climate Change"/> which states: {{quote|Global climate change is real and measurable...To reduce the global net economic, environmental and social losses in the face of these impacts, the policy objective must remain squarely focused on returning greenhouse gas concentrations to near pre-industrial levels through the reduction of emissions. The spatial and temporal fingerprint of warming can be traced to increasing greenhouse gas concentrations in the atmosphere, which are a direct result of burning fossil fuels, broad-scale deforestation and other human activity.}}
* United States National Research Council through its Committee on the Science of Climate Change in 2001, published ''Climate Change Science: An Analysis of Some Key Questions''.<ref name="CCSAASKQ">{{cite book |author=Committee on the Science of Climate Change, Division on Earth and Life Studies, National Research Council |title=Climate Change Science: An Analysis of Some Key Questions |publisher=National Academy Press |location=Washington DC |year=2001 |isbn=0-309-07574-2 |url=http://books.nap.edu/html/climatechange |archive-url=https://web.archive.org/web/20010628070322/http://books.nap.edu/html/climatechange/ |dead-url=yes |archive-date=2001-06-28 }}</ref> This report explicitly endorses the IPCC view of attribution of recent climate change as representing the view of the scientific community: {{quote|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 name="CCSAASKQ"/>}}
* Royal Society of New Zealand having signed onto the first joint science academy statement in 2001, released a separate statement in 2008 in order to clear up "the controversy over climate change and its causes, and possible confusion among the public": {{quote|The globe is warming because of increasing greenhouse gas emissions. Measurements show that greenhouse gas concentrations in the atmosphere are well above levels seen for many thousands of years. Further global climate changes are predicted, with impacts expected to become more costly as time progresses. Reducing future impacts of climate change will require substantial reductions of greenhouse gas emissions.<ref name="Climate change statement from the Royal Society of New Zealand"/>}}
* The Royal Society of the United Kingdom has not changed its concurring stance reflected in its participation in joint national science academies' statements on anthropogenic global warming. According to the Telegraph, "The most prestigious group of scientists in the country was forced to act after fellows complained that doubts over man made global warming were not being communicated to the public".<ref name="telegraph.co.uk"/> In May 2010, it announced that it "is presently drafting a new public facing document on climate change, to provide an updated status report on the science in an easily accessible form, also addressing the levels of certainty of key components."<ref name="RS-CC"/> The society says that it is three years since the last such document was published and that, after an extensive process of debate and review,<ref name="Society to review climate message"/><ref name="Some excitable climate-change deniers just don't understand what science is"/> the new document was printed in September 2010. It summarises the current scientific evidence and highlights the areas where the science is well established, where there is still some debate, and where substantial uncertainties remain. The society has stated that "this is not the same as saying that the climate science itself is in error – no Fellows have expressed such a view to the RS".<ref name="RS-CC"/>  The introduction includes this statement: {{quote|There is strong evidence that the warming of the Earth over the last half-century has been caused largely by human activity, such as the burning of fossil fuels and changes in land use, including agriculture and deforestation.}}

===== International science academies =====
* African Academy of Sciences in 2007 was a signatory to the "statement on sustainability, energy efficiency, and climate change". This joint statement of African science academies, was organized through the Network of African Science Academies. Its stated goal was "to convey information and spur action on the occasion of the G8 Summit in Heiligendamm, Germany, in June 2007". {{quote|A consensus, based on current evidence, now exists within the global scientific community that human activities are the main source of climate change and that the burning of fossil fuels is largely responsible for driving this change.<ref>{{cite web|title=Joint statement by the Network of African Science Academies (NASAC) to the G8 on sustainability,  energy efficiency and climate change|url=http://www.interacademies.net/file.aspx?id=4825|accessdate=22 May 2015|date=2007|quote=A consensus, based on current evidence, now exists within the global scientific community that human activities are the main source of climate change and that the burning of fossil fuels is largely responsible for driving this change... Although we recognize that this nexus poses daunting challenges for the developed world, we firmly believe that these challenges are even more daunting for the most impoverished, science-poor regions of the developing world, especially in Africa.}}</ref>}}
* [[Organization:European Academy of Sciences and Arts|European Academy of Sciences and Arts]] in 2007 issued a formal declaration on climate change titled ''Let's Be Honest'': {{quote|Human activity is most ''likely'' responsible for climate warming. Most of the climatic warming over the last 50 years is ''likely'' to have been caused by increased concentrations of greenhouse gases in the atmosphere. Documented long-term climate changes include changes in Arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and [[Earth:Extreme weather|extreme weather]] including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones. The above development potentially has dramatic consequences for mankind's future.<ref name="euro-acad"/>}}
* European Science Foundation in a 2007 position paper <ref name="European Science Foundation Position Paper ''Impacts of Climate Change on the European Marine and Coastal Environment — Ecosystems Approach''"/> states: {{quote|There is now convincing evidence that since the industrial revolution, human activities, resulting in increasing concentrations of greenhouse gases have become a major agent of climate change... On-going and increased efforts to mitigate climate change through reduction in greenhouse gases are therefore crucial.}}
* InterAcademy Council As the representative of the world's scientific and engineering academies,<ref name="nytimes"/><ref name="interacademycouncil"/> the InterAcademy Council issued a report in 2007 titled ''Lighting the Way: Toward a Sustainable Energy Future''. {{quote|Current patterns of energy resources and energy usage are proving detrimental to the long-term welfare of humanity. The integrity of essential natural systems is already at risk from climate change caused by the atmospheric emissions of greenhouse gases.<ref name="interacademycouncil7"/> Concerted efforts should be mounted for improving energy efficiency and reducing the carbon intensity of the world economy.<ref name="interacademycouncil8"/>}}
* International Council of Academies of Engineering and Technological Sciences (CAETS) in 2007, issued a ''Statement on Environment and Sustainable Growth'':<ref name="caets">{{cite web |url=http://www.caets.org/nae/naecaets.nsf/(weblinks)/WSAN-78QL9A?OpenDocument |title=Archived copy |accessdate=2008-04-18 |deadurl=yes |archiveurl=https://web.archive.org/web/20081210053304/http://www.caets.org/nae/naecaets.nsf/(weblinks)/WSAN-78QL9A?OpenDocument |archivedate=2008-12-10 |df= }}</ref> {{quote|As reported by the Intergovernmental Panel on Climate Change (IPCC), most of the observed global warming since the mid-20th century is very likely due to human-produced emission of greenhouse gases and this warming will continue unabated if present anthropogenic emissions continue or, worse, expand without control. CAETS, therefore, endorses the many recent calls to decrease and control greenhouse gas emissions to an acceptable level as quickly as possible.}}

==== Physical and chemical sciences ====
* [[Organization:American Chemical Society|American Chemical Society]]<ref name="American Chemical Society ''Global Climate Change''"/>
* [[Organization:American Institute of Physics|American Institute of Physics]]<ref name="American Institute of Physics Statement supporting AGU statement on human-induced climate change"/>
* [[Organization:American Physical Society|American Physical Society]]<ref name="American Physical Society Climate Change Policy Statement"/>
* [[Organization:Australian Institute of Physics|Australian Institute of Physics]]<ref name="AIP science policy document."/>
* [[Organization:European Physical Society|European Physical Society]]<ref name="EPS Position Paper ''Energy for the future: The Nuclear Option''"/>

==== Earth sciences ====

===== American Geophysical Union =====
The [[Organization:American Geophysical Union|American Geophysical Union]] (AGU) adopted a statement on ''Climate Change and Greenhouse Gases'' in 1998.<ref>{{cite journal |first=Tamara S. |last=Ledley |first2=Eric T. |last2=Sundquist |first3=Stephen E. |last3=Schwartz |first4=Dorothy K. |last4=Hall |first5=Jack D. |last5=Fellows |first6=Timothy L. |last6=Killeen |title=Climate Change and Greenhouse Gases |journal=EOS |date=September 28, 1999 |volume=80 |issue=39 |pages=453–454, 457–458 |doi=10.1029/99EO00325 |quote=There is no known geologic precedent for large increases of atmospheric C0<sub>2</sub> without simultaneous changes in other components of the carbon cycle and climate system.[...] Changes in the climate system that are confidently predicted in response to increases in greenhouse gases include increases in mean surface air temperature, increases in global mean rates of precipitation and evaporation, rising sea level, and changes in the biosphere. |url=http://www.ecd.bnl.gov/pubs/BNL66903.pdf |accessdate=16 August 2016 |bibcode=1999EOSTr..80Q.453L |archive-url=https://web.archive.org/web/20161009000325/http://www.ecd.bnl.gov/pubs/BNL66903.pdf |archive-date=2016-10-09 |dead-url=yes |df= }}</ref> A new statement, adopted by the society in 2003, revised in 2007,<ref name="agu"/> and revised and expanded in 2013,<ref>{{cite web|title=Human-induced Climate Change Requires Urgent Action|url=http://www.agu.org/news/press/pr_archives/2013/2013-38.shtml|work=Position Statement|publisher=American Geophysical Union|accessdate=14 August 2013}}</ref> affirms that rising levels of greenhouse gases have caused and will continue to cause the global surface temperature to be warmer:

{{quote|Human activities are changing Earth's climate. At the global level, atmospheric concentrations of carbon dioxide and other heat-trapping greenhouse gases have increased sharply since the Industrial Revolution. Fossil fuel burning dominates this increase. Human-caused increases in greenhouse gases are responsible for most of the observed global average surface warming of roughly 0.8{{nnbsp}}°C (1.5{{nnbsp}}°F) over the past 140 years. Because natural processes cannot quickly remove some of these gases (notably carbon dioxide) from the atmosphere, our past, present, and future emissions will influence the climate system for millennia.

While important scientific uncertainties remain as to which particular impacts will be experienced where, no uncertainties are known that could make the impacts of climate change inconsequential. Furthermore, surprise outcomes, such as the unexpectedly rapid loss of Arctic summer sea ice, may entail even more dramatic changes than anticipated.}}

===== American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America =====
In May, 2011, the American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and [[Organization:Soil Science Society of America|Soil Science Society of America]] (SSSA) issued a joint position statement on climate change as it relates to agriculture:

{{quote|A comprehensive body of scientific evidence indicates beyond reasonable doubt that global climate change is now occurring and that its manifestations threaten the stability of societies as well as natural and managed ecosystems. Increases in ambient temperatures and changes in related processes are directly linked to rising anthropogenic greenhouse gas (GHG) concentrations in the atmosphere.

Unless the emissions of GHGs are curbed significantly, their concentrations will continue to rise, leading to changes in temperature, precipitation, and other climate variables that will undoubtedly affect agriculture around the world.

Climate change has the potential to increase weather variability as well as gradually increase global temperatures. Both of these impacts have the potential to negatively impact the adaptability and resilience of the world's food production capacity; current research indicates climate change is already reducing the productivity of vulnerable cropping systems.<ref name="soils"/>}}

===== European Federation of Geologists =====
In 2008, the European Federation of Geologists<ref name="eurogeologists"/> (EFG) issued the position paper ''Carbon Capture and geological Storage '':

{{quote|The EFG recognizes the work of the IPCC and other organizations, and subscribes to the major findings that climate change is happening, is predominantly caused by anthropogenic emissions of {{CO2}}, and poses a significant threat to human civilization.

It is clear that major efforts are necessary to quickly and strongly reduce {{CO2}} emissions. The EFG strongly advocates renewable and sustainable energy production, including geothermal energy, as well as the need for increasing energy efficiency.

CCS [Carbon Capture and geological Storage] should also be regarded as a bridging technology, facilitating the move towards a carbon free economy.<ref name="eurogeologists9"/>}}

===== European Geosciences Union =====
In 2005, the Divisions of Atmospheric and Climate Sciences of the [[Organization:European Geosciences Union|European Geosciences Union]] (EGU) issued a position statement in support of the [[Earth:Scientific opinion on climate change#Joint science academies’ statement 2005|joint science academies’ statement]] on global response to climate change. The statement refers to the [[Organization:Intergovernmental Panel on Climate Change|Intergovernmental Panel on Climate Change]] (IPCC), as "the main representative of the global [[Philosophy:Scientific community|scientific community]]", and asserts that the IPCC

{{quote|represents the state-of-the-art of climate science supported by the major science academies around the world and by the vast majority of science researchers and investigators as documented by the peer-reviewed scientific literature.<ref name="www"/>}}

Additionally, in 2008, the EGU issued a position statement on [[Biology:Ocean acidification|ocean acidification]] which states, "Ocean acidification is already occurring today and will continue to intensify, closely tracking atmospheric {{CO2}} increase. Given the potential threat to marine ecosystems and its ensuing impact on human society and economy, especially as it acts in conjunction with anthropogenic global warming, there is an urgent need for immediate action." The statement then advocates for strategies "to limit future release of {{CO2}} to the atmosphere and/or enhance removal of excess {{CO2}} from the atmosphere."<ref name="www10"/>

===== Geological Society of America =====
In 2006, the Geological Society of America adopted a position statement on global [[Earth:Climate change|climate change]]. It amended this position on April 20, 2010 with more explicit comments on need for {{CO2}} reduction.
{{quote|Decades of scientific research have shown that climate can change from both natural and anthropogenic causes. The Geological Society of America (GSA) concurs with assessments by the National Academies of Science (2005), the National Research Council (2006), and the Intergovernmental Panel on Climate Change (IPCC, 2007) that global climate has warmed and that human activities (mainly greenhouse‐gas emissions) account for most of the warming since the middle 1900s. If current trends continue, the projected increase in global temperature by the end of the twenty first century will result in large impacts on humans and other species. Addressing the challenges posed by climate change will require a combination of adaptation to the changes that are likely to occur and global reductions of {{CO2}} emissions from anthropogenic sources.<ref name="geosociety"/>}}

===== Geological Society of London =====
In November 2010, the Geological Society of London issued the position statement ''Climate change: evidence from the geological record'':

{{quote|The last century has seen a rapidly growing global population and much more intensive use of resources, leading to greatly increased emissions of gases, such as carbon dioxide and methane, from the burning of fossil fuels (oil, gas and coal), and from agriculture, cement production and deforestation. Evidence from the geological record is consistent with the physics that shows that adding large amounts of carbon dioxide to the atmosphere warms the world and may lead to: higher sea levels and flooding of low-lying coasts; greatly changed patterns of rainfall; increased acidity of the oceans; and decreased oxygen levels in seawater.

There is now widespread concern that the Earth's climate will warm further, not only because of the lingering effects of the added carbon already in the system, but also because of further additions as human population continues to grow. Life on Earth has survived large climate changes in the past, but extinctions and major redistribution of species have been associated with many of them. When the human population was small and nomadic, a rise in sea level of a few metres would have had very little effect on Homo sapiens. With the current and growing global population, much of which is concentrated in coastal cities, such a rise in sea level would have a drastic effect on our complex society, especially if the climate were to change as suddenly as it has at times in the past. Equally, it seems likely that as warming continues some areas may experience less precipitation leading to drought. With both rising seas and increasing drought, pressure for human migration could result on a large scale.<ref name="geolsoc"/>}}

===== International Union of Geodesy and Geophysics =====
In July 2007, the [[Organization:International Union of Geodesy and Geophysics|International Union of Geodesy and Geophysics]] (IUGG) adopted a resolution titled "The Urgency of Addressing Climate Change". In it, the IUGG concurs with the "comprehensive and widely accepted and endorsed scientific assessments carried out by the Intergovernmental Panel on Climate Change and regional and national bodies, which have firmly established, on the basis of scientific evidence, that human activities are the primary cause of recent climate change." They state further that the "continuing reliance on combustion of fossil fuels as the world's primary source of energy will lead to much higher atmospheric concentrations of greenhouse gases, which will, in turn, cause significant increases in surface temperature, sea level, ocean acidification, and their related consequences to the environment and society."<ref name="iugg"/>

===== National Association of Geoscience Teachers =====
In July 2009, the National Association of Geoscience Teachers<ref name="nagt"/> (NAGT) adopted a position statement on climate change in which they assert that "Earth's climate is changing [and] "that present warming trends are largely the result of human activities":

{{quote|NAGT strongly supports and will work to promote education in the science of climate change, the causes and effects of current global warming, and the immediate need for policies and actions that reduce the emission of greenhouse gases.<ref name="nagt11"/>}}

==== Meteorology and oceanography ====

===== American Meteorological Society =====
The American Meteorological Society (AMS) statement adopted by their council in 2012 concluded:

{{quote|There is unequivocal evidence that Earth's lower atmosphere, ocean, and land surface are warming; sea level is rising; and snow cover, mountain glaciers, and Arctic sea ice are shrinking. The dominant cause of the warming since the 1950s is human activities. This scientific finding is based on a large and persuasive body of research. The observed warming will be irreversible for many years into the future, and even larger temperature increases will occur as greenhouse gases continue to accumulate in the atmosphere. Avoiding this future warming will require a large and rapid reduction in global greenhouse gas emissions. The ongoing warming will increase risks and stresses to human societies, economies, ecosystems, and wildlife through the 21st century and beyond, making it imperative that society respond to a changing climate. To inform decisions on adaptation and mitigation, it is critical that we improve our understanding of the global climate system and our ability to project future climate through continued and improved monitoring and research. This is especially true for smaller (seasonal and regional) scales and weather and climate extremes, and for important hydroclimatic variables such as precipitation and water availability.

Technological, economic, and policy choices in the near future will determine the extent of future impacts of climate change. Science-based decisions are seldom made in a context of absolute certainty. National and international policy discussions should include consideration of the best ways to both adapt to and mitigate climate change. Mitigation will reduce the amount of future climate change and the risk of impacts that are potentially large and dangerous. At the same time, some continued climate change is inevitable, and policy responses should include adaptation to climate change. Prudence dictates extreme care in accounting for our relationship with the only planet known to be capable of sustaining human life.<ref name="ametsoc"/>}}

===== Australian Meteorological and Oceanographic Society =====
The [[Organization:Australian Meteorological and Oceanographic Society|Australian Meteorological and Oceanographic Society]] has issued a ''Statement on Climate Change'', wherein they conclude:

{{quote|Global climate change and global warming are real and observable ... It is highly likely that those human activities that have increased the concentration of greenhouse gases in the atmosphere have been largely responsible for the observed warming since 1950. The warming associated with increases in greenhouse gases originating from human activity is called the enhanced [[Earth:Greenhouse effect|greenhouse effect]]. The atmospheric concentration of carbon dioxide has increased by more than 30% since the start of the industrial age and is higher now than at any time in at least the past 650,000 years. This increase is a direct result of burning fossil fuels, broad-scale deforestation and other human activity."<ref name="amos"/>}}

===== Canadian Foundation for Climate and Atmospheric Sciences =====
In November 2005, the [[Organization:Canadian Foundation for Climate and Atmospheric Sciences|Canadian Foundation for Climate and Atmospheric Sciences]] (CFCAS) issued a letter to the Prime Minister of Canada stating that

{{quote|We concur with the climate science assessment of the Intergovernmental Panel on Climate Change (IPCC) in 2001 ... We endorse the conclusions of the IPCC assessment that 'There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities'. ... There is increasingly unambiguous evidence of changing climate in Canada and around the world. There will be increasing impacts of climate change on Canada's natural ecosystems and on our socio-economic activities. Advances in climate science since the 2001 IPCC Assessment have provided more evidence supporting the need for action and development of a strategy for adaptation to projected changes.<ref name="cfcas"/>}}

===== Canadian Meteorological and Oceanographic Society =====
In November 2009,  a letter to the Canadian Parliament by The [[Organization:Canadian Meteorological and Oceanographic Society|Canadian Meteorological and Oceanographic Society]] states:
{{quote|Rigorous international research, including work carried out and supported by the Government of Canada, reveals that greenhouse gases resulting from human activities contribute to the warming of the atmosphere and the oceans and constitute a serious risk to the health and safety of our society, as well as having an impact on all life.<ref name="cmos"/>}}

===== Royal Meteorological Society (UK) =====
In February 2007, after the release of the IPCC's Fourth Assessment Report, the Royal Meteorological Society issued an endorsement of the report. In addition to referring to the IPCC as "[the] world's best climate scientists", they stated that climate change is happening as "the result of emissions since industrialization and we have already set in motion the next 50 years of global warming – what we do from now on will determine how worse it will get."<ref name="rmets"/>

===== World Meteorological Organization =====
In its ''Statement at the Twelfth Session of the Conference of the Parties to the U.N. Framework Convention on Climate Change'' presented on November 15, 2006, the [[Organization:World Meteorological Organization|World Meteorological Organization]] (WMO) confirms the need to "prevent dangerous anthropogenic interference with the climate system." The WMO concurs that "scientific assessments have increasingly reaffirmed that human activities are indeed changing the composition of the atmosphere, in particular through the burning of fossil fuels for energy production and transportation." The WMO concurs that "the present atmospheric concentration of {{CO2}} was never exceeded over the past 420,000 years;" and that the IPCC "assessments provide the most authoritative, up-to-date scientific advice."
<ref name="www12">{{cite web|url=http://www.wmo.ch/pages/mediacentre/statann/documents/SG21_2006_E.pdf|title=WMO's Statement at the Twelfth Session of the Conference of the Parties to the U.N. Framework Convention on Climate Change.|publisher=}}</ref>

===== American Quaternary Association =====
The [[Organization:American Quaternary Association|American Quaternary Association]] (AMQUA) has stated

{{quote|Few credible Scientists now doubt that humans have influenced the documented rise of global temperatures since the Industrial Revolution," citing "the growing body of evidence that warming of the atmosphere, especially over the past 50 years, is directly impacted by human activity.<ref name="agu13"/>}}

===== International Union for Quaternary Research =====
The statement on climate change issued by the [[Organization:International Union for Quaternary Research|International Union for Quaternary Research]] (INQUA) reiterates the conclusions of the IPCC, and urges all nations to take prompt action in line with the UNFCCC principles.

{{quote|Human activities are now causing atmospheric concentrations of greenhouse gases — including carbon dioxide, methane, tropospheric ozone, and nitrous oxide — to rise well above pre-industrial levels….Increases in greenhouse gases are causing temperatures to rise…The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action….Minimizing the amount of this carbon dioxide reaching the atmosphere presents a huge challenge but must be a global priority.<ref name="inqua"/>}}

==== Biology and life sciences ====
Life science organizations have outlined the dangers climate change pose to wildlife.
* American Association of Wildlife Veterinarians<ref name="AAWV ''Position Statement on Climate Change, Wildlife Diseases, and Wildlife Health''"/>
* [[Organization:American Institute of Biological Sciences|American Institute of Biological Sciences]]. In October 2009, the leaders of 18 US scientific societies and organizations sent an open letter to the United States Senate reaffirming the scientific consensus that climate change is occurring and is primarily caused by human activities.  The American Institute of Biological Sciences (AIBS) adopted this letter as their official position statement.<ref name="AIBS Position Statements"/><ref name="Scientific societies warn Senate: climate change is real"/> The letter goes on to warn of predicted impacts on the United States such as [[Earth:Sea level rise|sea level rise]] and increases in extreme weather events, [[Water scarcity|water scarcity]], heat waves, wildfires, and the disturbance of biological systems.  It then advocates for a dramatic reduction in emissions of greenhouse gases.<ref name="Letter to US Senators"/>
* [[Organization:American Society for Microbiology|American Society for Microbiology]]<ref name="Global Environmental Change — Microbial Contributions, Microbial Solutions"/>
* Australian Coral Reef Society<ref name="Australian Coral Reef Society official letter"/>
* [[Organization:Institute of Biology|Institute of Biology]] (UK)<ref name="iob"/>
* Society of American Foresters issued two position statements pertaining to climate change in which they cite the IPCC<ref name="SAF ''Forest Management and Climate Change ''"/> and the UNFCCC.<ref name="SAF ''Forest Offset Projects in a Carbon Trading System''"/>
* The Wildlife Society (international)<ref name="Wildlife Society ''Global Climate Change and Wildlife''"/>

==== Human health ====
A number of health organizations have warned about the numerous [[Earth:Effects of global warming on human health|negative health effects of global warming]]
* American Academy of Pediatrics<ref name="AAP ''Global Climate Change and Children's Health''"/>
* American College of Preventive Medicine<ref name="ACPM Policy Statement ''Abrupt Climate Change and Public Health Implications''"/>
* American Medical Association<ref name="American Medical Association Policy Statement"/>
* [[Organization:American Public Health Association|American Public Health Association]]<ref name="apha"/>
* Australian Medical Association in 2004<ref name="AMA ''Climate Change and Human Health — 2004''"/> and in 2008<ref name="AMA ''Climate Change and Human Health'' — 2004. Revised 2008."/>
* World Federation of Public Health Associations<ref name="wfpha"/>
* [[Organization:World Health Organization|World Health Organization]]<ref name="WHO ''Protecting health from climate change''"/>

{{quote|There is now widespread agreement that the Earth is warming, due to emissions of greenhouse gases caused by human activity. It is also clear that current trends in energy use, development, and population growth will lead to continuing – and more severe – climate change.}}

{{quote|The changing climate will inevitably affect the basic requirements for maintaining health: clean air and water, sufficient food and adequate shelter. Each year, about 800,000 people die from causes attributable to urban air pollution, 1.8 million from diarrhoea resulting from lack of access to clean water supply, sanitation, and poor hygiene, 3.5 million from [[Medicine:Malnutrition|malnutrition]] and approximately 60,000 in natural disasters. A warmer and more variable climate threatens to lead to higher levels of some air pollutants, increase transmission of diseases through unclean water and through contaminated food, to compromise agricultural production in some of the least developed countries, and increase the hazards of extreme weather.}}

==== Miscellaneous ====
A number of other national scientific societies have also endorsed the opinion of the IPCC:
* American Astronomical Society<ref name="Statement supporting AGU statement on human-induced climate change"/>
* American Statistical Association<ref name="ASA Statement on Climate Change"/>
* Canadian Council of Professional Engineers  <ref>{{cite web |last1= Lapp |first1= David |title= What Is Climate Change |url= http://www.engineerscanada.ca/climate-change |work= Canadian Council of Professional Engineers |accessdate= 18 August 2015}}</ref>
* The Institution of Engineers Australia<ref name="Policy Statement, Climate Change and Energy"/>
* International Association for Great Lakes Research<ref name="IAGLR Fact Sheet ''The Great Lakes at a Crossroads: Preparing for a Changing Climate''"/>
* Institute of Professional Engineers New Zealand<ref name="IPENZ Informatory Note, ''Climate Change and the greenhouse effect''"/>
* [http://www.wfeo.net/events/international-conclave-on-climate-change/%20%20 The World Federation of Engineering Organizations (WFEO)]

=== Non-committal ===
{{anchor|Non-committal statements}}

==== American Association of Petroleum Geologists ====
As of June 2007, the [[Organization:American Association of Petroleum Geologists|American Association of Petroleum Geologists]] (AAPG) Position Statement on climate change stated:

{{quote|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 name="aapg"/>}}

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"/> Explaining the plan for a revision, AAPG president Lee Billingsly wrote in March 2007:

{{quote|Members have threatened to not renew their memberships… if AAPG does not alter its position on global climate change... And I have been told of members who already have resigned in previous years because of our current global climate change position… The current policy statement is not supported by a significant number of our members and prospective members.<ref name="aapg14"/>}}

AAPG President John Lorenz announced the "sunsetting" of AAPG's Global Climate Change Committee in January 2010.  The AAPG Executive Committee determined:

{{quote|Climate change is peripheral at best to our science […] AAPG does not have credibility in that field […] and as a group we have no particular knowledge of global atmospheric geophysics.<ref name="2010_tpgmarapr"/>}}

==== American Institute of Professional Geologists (AIPG) ====
The official position statement from AIPG on the Environment states that "combustion of fossil fuel include and the generation of GHGs [greenhouse gases] including carbon dioxide (CO2) and methane (CH4).  Emissions of GHGs are perceived by some to be one of the largest, global environmental concerns related to energy production due to potential effects on the global energy system and possibly global climate. Fossil fuel use is the primary source of the increased atmospheric concentration of GHGs since industrialization".<ref>{{cite web |title=AIPG Position Statements |url=http://aipg.org/posstatements |accessdate=2018-02-01}}</ref>

In March 2010, AIPG's Executive Director issued a statement regarding polarization of opinions on climate change within the membership and announced that the AIPG Executive had made a decision to cease publication of articles and opinion pieces concerning climate change in AIPG's news journal, ''The Professional Geologist''.<ref name="aipg17"/>

=== Opposing ===

Since 2007, when the [[Organization:American Association of Petroleum Geologists|American Association of Petroleum Geologists]] released a revised statement,<ref name="aapg19"/> no national or international scientific body rejects the findings of human-induced effects on climate change.<ref name=AQAonAAPG/><ref name=Oreskes07p68/>

== Surveys of scientists and scientific literature ==
{{Main article|Earth:Surveys of scientists' views on climate change}}
[[File:Climate science opinion2.png|thumb|Summary of opinions from climate and earth scientists regarding climate change. Click to see a more detailed summary of the sources.]]
[[File:Cook et al. (2016) Studies consensus.jpg|thumb|Seven papers into man-made global warming consensus, from 2004–2015, by Naomi Oreskes,<ref name="Beyond the Ivory Tower: The Scientific Consensus on Climate Change"/> Peter Doran,<ref name=DZ_EOS_2009/> William Anderegg,<ref name="Expert credibility in climate change"/> Bart Verheggen,<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=Environmental Science & Technology|date=19 August 2014|volume=48|issue=16|pages=8963–8971|doi=10.1021/es501998e|pmid=25051508|issn=0013-936X|bibcode=2014EnST...48.8963V}}</ref> Neil Stenhouse,<ref>{{cite journal|last1=Stenhouse|first1=Neil|last2=Maibach|first2=Edward|last3=Cobb|first3=Sara|last4=Ban|first4=Ray|last5=Bleistein|first5=Andrea|last6=Croft|first6=Paul|last7=Bierly|first7=Eugene|last8=Seitter|first8=Keith|last9=Rasmussen|first9=Gary|last10=Leiserowitz|first10=Anthony|title=Meteorologists' Views About Global Warming: A Survey of American Meteorological Society Professional Members|journal=Bulletin of the American Meteorological Society|date=8 November 2013|volume=95|issue=7|pages=1029–1040|doi=10.1175/BAMS-D-13-00091.1|issn=0003-0007|bibcode=2014BAMS...95.1029S}}</ref> J. Stuart Carlton,<ref>{{cite journal|last1=Carlton|first1=J. S.|last2=Perry-Hill|first2=Rebecca|last3=Huber|first3=Matthew|last4=Prokopy|first4=Linda S.|title=The climate change consensus extends beyond climate scientists|journal=Environmental Research Letters|date=1 January 2015|volume=10|issue=9|page=094025|doi=10.1088/1748-9326/10/9/094025|language=en|issn=1748-9326|bibcode=2015ERL....10i4025C}}</ref> and John Cook.<ref name="Cook_etal_13"/><ref name=ConsensusOnConsensus2016/>]]

Various surveys have been conducted to evaluate scientific opinion on [[Earth:Global warming|global warming]]. They have concluded that the majority of scientists support the idea of anthropogenic climate change.

In 2004, the geologist and historian of science [[Biography:Naomi Oreskes|Naomi Oreskes]] summarized a study of the scientific literature on climate change.<ref name="Beyond the Ivory Tower: The Scientific Consensus on Climate Change"/> She analyzed 928 [[Abstract (summary)|abstracts]] of papers from refereed scientific journals between 1993 and 2003 and concluded that there is a scientific consensus on the reality of anthropogenic climate change.

Oreskes divided the abstracts into six categories: explicit endorsement of the consensus position, evaluation of impacts, mitigation proposals, methods, [[Earth:Paleoclimatology|paleoclimate]] analysis, and rejection of the consensus position. Seventy-five per cent of the abstracts were placed in the first three categories (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."

In 2007, Harris Interactive surveyed 489 randomly selected members of either the American Meteorological Society or the [[Organization:American Geophysical Union|American Geophysical Union]] for the [[Organization:Statistical Assessment Service|Statistical Assessment Service]] (STATS) at [[Organization:George Mason University|George Mason University]]. 97% of the scientists surveyed agreed that global temperatures had increased during the past 100 years; 84% said they personally believed human-induced warming was occurring, and 74% agreed that "currently available scientific evidence" substantiated its occurrence. Catastrophic effects in 50–100 years would likely be observed according to 41%, while 44% thought the effects would be moderate and about 13 percent saw relatively little danger. 5% said they thought human activity did not contribute to greenhouse warming.<ref name="Survey Tracks Scientists' Growing Climate Concern"/><ref name="Climate Scientists Agree on Warming, Disagree on Dangers, and Don't Trust the Media's Coverage of Climate Change">{{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=2008-04-24 |accessdate=2010-01-20 |deadurl=yes |archiveurl=https://web.archive.org/web/20100111104946/http://stats.org/stories/2008/global_warming_survey_apr23_08.html |archivedate=2010-01-11 |df= }}</ref><ref name="journalistsresource"/><ref name="The Structure of Scientific Opinion on Climate Change"/>

Dennis Bray and Hans von Storch conducted a survey in August 2008 of 2058 climate scientists from 34 different countries.<ref name="A Survey of the Perspectives of Climate Scientists Concerning Climate Science and Climate Change"/> A web link with a unique identifier was given to each respondent to eliminate multiple responses. A total of 373 responses were received giving an overall response rate of 18.2%. No paper on climate change consensus based on this survey has been published yet (February 2010), but one on another subject has been published based on the survey.<ref name="Prediction' or 'Projection; The nomenclature of climate science"/>

The survey was composed of 76 questions split into a number of sections.
There were sections on the demographics of the respondents, their assessment of the state of climate science, how good the science is, climate change impacts, adaptation and mitigation, their opinion of the IPCC, and how well climate science was being communicated to the public.
Most of the answers were on a scale from 1 to 7 from 'not at all' to 'very much'.

To the question "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 67.1% said they very much agreed, 26.7% agreed to some large extent, 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.

A poll performed by [[Biography:Peter Doran|Peter Doran]] and Maggie Kendall Zimmerman at [[Organization:University of Illinois at Chicago|University of Illinois at Chicago]] received replies from 3,146 of the 10,257 polled Earth scientists. Results were analyzed globally and by specialization. 76 out of 79 climatologists who "listed climate science as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change" believed that mean global temperatures had risen compared to pre-1800s levels. Seventy-five of 77 believed that human activity is a significant factor in changing mean global temperatures. 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 [[Meteorologist|meteorologist]]s were among the biggest doubters, with only 47 percent and 64 percent, respectively, believing in significant human involvement. The authors summarised the findings:

{{quote|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.<ref name="DZ_EOS_2009"/>}}

A 2010 paper in the ''Proceedings of the National Academy of Sciences of the United States'' (PNAS) reviewed publication and citation data for 1,372 climate researchers and drew the following two conclusions:

<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 name="Expert credibility in climate change"/></blockquote>

A 2013 paper in Environmental Research Letters reviewed 11,944 abstracts of scientific papers matching "global warming" or "global climate change". They found 4,014 which discussed the cause of recent global warming, and of these "97.1% endorsed the consensus position that humans are causing global warming".<ref name="Cook_etal_13"/> This study was criticised by Richard Tol.<ref name="Tol p=048001">{{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}}</ref>

James L. Powell, a former member of the [[Organization:National Science Board|National Science Board]] and current executive director of the [[Organization:National Physical Science Consortium|National Physical Science Consortium]], 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 rejected anthropogenic global warming.<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|accessdate=14 February 2014}}</ref> A follow-up analysis looking at 2,258 peer-reviewed climate articles with 9,136 authors published between November 2012 and December 2013 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|accessdate=14 February 2014}}</ref> His 2015 paper on the topic, covering 24,210 articles published by 69,406 authors during 2013 and 2014 found only five articles by four authors rejecting anthropogenic global warming. Over 99.99% of climate scientists did not reject AGW in their peer-reviewed research.<ref name=Powell2015>{{cite journal|last1=Powell|first1=James Lawrence|title=Climate Scientists Virtually Unanimous Anthropogenic Global Warming Is True|journal=Bulletin of Science, Technology & Society|date=1 October 2015|volume=35|issue=5–6|pages=121–124|doi=10.1177/0270467616634958|url=http://bst.sagepub.com/content/35/5-6/121|language=en|issn=0270-4676}}</ref>
[[File:The Consensus on Anthropogenic Global Warming, 2017.jpg|thumb|Peer-reviewed studies of the consensus on anthropogenic global warming.]]
In his latest paper, Powell reported that using rejection as the criterion of consensus, five surveys of the peer-reviewed literature from 1991 to 2015, including several of those above, combine to 54,195 articles with an average consensus of 99.94%.<ref>{{Cite journal|last=Powell|first=James Lawrence|date=2017-05-24|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}}</ref>

Replication studies have shown that the 2% of climate science papers that rejected the scientific consensus on climate change in 2016 were methodologically flawed.<ref>{{cite journal|title=Learning from mistakes in climate research|first1=Rasmus E.|last1=Benestad|first2=Dana|last2=Nuccitelli|first3=Stephan|last3=Lewandowsky|first4=Katharine|last4=Hayhoe|first5=Hans Olav|last5=Hygen|first6=Rob van|last6=Dorland|first7=John|last7=Cook|date=1 November 2016|journal=Theoretical and Applied Climatology|volume=126|issue=3–4|pages=699–703|doi=10.1007/s00704-015-1597-5|bibcode=2016ThApC.126..699B}}</ref>

== Existence of a scientific consensus ==
A question that frequently arises in popular discussion of climate change is whether there is a scientific consensus on climate change.<ref name="Oreskes_consensus"/>  Several scientific organizations have explicitly used the term "consensus" in their statements:
* American Association for the Advancement of Science, 2006: "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 name="aaas board"/>
* US National Academy of Sciences: "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, [the National Academies’ reports] have assessed consensus findings on the science..."<ref name="nas"/>
* Joint Science Academies' statement, 2005: "We recognise the international scientific consensus of the Intergovernmental Panel on Climate Change (IPCC)."<ref name="nationalacademies21"/>
* 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 name="The Science of Climate Change"/>
* American Meteorological Society, 2003: "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 name="ametsoc22"/>
* Network of African Science Academies: "A consensus, based on current evidence, now exists within the global scientific community that human activities are the main source of climate change and that the burning of fossil fuels is largely responsible for driving this change."<ref name="autogenerated1" />
* [[Organization:International Union for Quaternary Research|International Union for Quaternary Research]], 2008: "INQUA recognizes the international scientific consensus of the Intergovernmental Panel on Climate Change (IPCC)."<ref name="inqua"/>
* Australian Coral Reef Society,<ref name="australiancoralreefsociety"/> 2006: "There is almost total consensus among experts that the earth's climate is changing as a result of the build-up of greenhouse gases.... There is broad scientific consensus that coral reefs are heavily affected by the activities of man and there are significant global influences that can make reefs more vulnerable such as global warming...."<ref name="australiancoralreefsociety24"/>

== See also ==
* 4 Degrees and Beyond International Climate Conference
* [[Earth:Climate change denial|Climate change denial]]
* [[Earth:Economics of global warming|Economics of global warming]]
* [[Biology:Effects of global warming|Effects of global warming]]
* [[Gateway belief model]]
* [[Earth:History of climate change science|History of climate change science]]
* [[Earth:International Year of Planet Earth|International Year of Planet Earth]]
* List of authors of ''Climate Change 2007: The Physical Science Basis''
* List of climate scientists
* National Registry of Environmental Professionals#Climate change survey – a survey on climate change

== References ==
{{reflist|refs=

<ref name="AmericasClimateChoices-2010-SciPanel">[Notes-SciPanel] {{Cite book | publisher = The National Academies Press | isbn = 0-309-14588-0 | last = America's Climate Choices: Panel on Advancing the Science of Climate Change; National Research Council | title = Advancing the Science of Climate Change | location = Washington, D.C. | year = 2010 | url = http://www.nap.edu/catalog.php?record_id=12782 | quote = (p1) ... there is a strong, credible body of evidence, based on multiple lines of research, documenting that climate is changing and that these changes are in large part caused by human activities. While much remains to be learned, the core phenomenon, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious scientific debate and careful evaluation of alternative explanations. * * * (p21-22) Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities. | deadurl = yes | archiveurl = https://web.archive.org/web/20140529161102/http://www.nap.edu/catalog.php?record_id=12782 | archivedate = 2014-05-29 | df =  }}</ref>

<ref name="Integration and Synthesis: Assessing Climate Change Impacts in Northern Canada">{{cite journal |author1=Ogden, Aynslie |author2=Cohen, Stewart |lastauthoramp=yes |title=''Integration and Synthesis: Assessing Climate Change Impacts in Northern Canada'' |year=2002 |url=http://www.taiga.net/nce/initiatives/publications/occasional_paper_02.pdf |format=PDF |accessdate=2009-04-12 |deadurl=yes |archiveurl=https://web.archive.org/web/20080513051044/http://www.taiga.net/nce/initiatives/publications/occasional_paper_02.pdf |archivedate=2008-05-13 |df= }}</ref>

<ref name="Scientific societies warn Senate: climate change is real">{{citation |url=https://arstechnica.com/tech-policy/news/2009/10/scientific-societies-warn-senate-climate-change-is-real.ars |title=''Scientific societies warn Senate: climate change is real'' | publisher=Ars Technica |date=October 22, 2009}}</ref>

<ref name="Cook_etal_13">{{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=Skuce |first8=Andrew |title=Quantifying the consensus on anthropogenic global warming in the scientific literature |journal=Environmental Research Letters |date=1 January 2013 |volume=8 |issue=2 |page=024024 |doi=10.1088/1748-9326/8/2/024024 |url=http://iopscience.iop.org/article/10.1088/1748-9326/8/2/024024/meta |language=en |issn=1748-9326 |bibcode=2013ERL.....8b4024C}}</ref>

<!--ref name="2009_tpgnovdec">[http://64.207.34.58/StaticContent/3/TPGs/2009_TPGNovDec.pdf "Ohio Section Members Vote to Oppose Markey-Waxman Cap & Trade Bill"], ''The Professional Geologist'', November/December 2009, p. 14-15</ref-->

<ref name="aaas board">[http://www.aaas.org/sites/default/files/migrate/uploads/aaas_climate_statement1.pdf AAAS Board Statement on Climate Change] ''www.aaas.org'' December 2006</ref>

<ref name="2010_tpgmarapr">[http://64.207.34.58/StaticContent/3/TPGs/2010_TPGMarApr.pdf ''Sunsetting the Global Climate Change Committee''], ''The Professional Geologist'', March/April 2010, p. 28</ref>

<!--ref name="2010_tpgjanfeb">[http://64.207.34.58/StaticContent/3/TPGs/2010_TPGJanFeb.pdf "AIPG Climate Change and Domestic Energy Statement"], ''The Professional Geologist'', January/February 2010, p. 42</ref-->

<!--ref name="2010_tpgmarapr18">[http://64.207.34.58/StaticContent/3/TPGs/2010_TPGMarApr.pdf "Climate Change and Society Governance"], ''The Professional Geologist'', March/April 2010, p. 33</ref-->

<ref name="A Survey of the Perspectives of Climate Scientists Concerning Climate Science and Climate Change">{{cite web |first1=Dennis |last1=Bray |first2=Hans |last2=von Storch |year=2009 |url=http://coast.gkss.de/staff/storch/pdf/CliSci2008.pdf |title=A Survey of the Perspectives of Climate Scientists Concerning Climate Science and Climate Change }}</ref>

<ref name="AAP ''Global Climate Change and Children's Health''">{{citation |url=http://aappolicy.aappublications.org/cgi/content/full/pediatrics;120/5/1149 |title=AAP ''Global Climate Change and Children's Health'' |year=2007 |access-date=2009-02-13 |archive-url=https://web.archive.org/web/20090722104801/http://aappolicy.aappublications.org/cgi/content/full/pediatrics;120/5/1149 |archive-date=2009-07-22 |dead-url=yes |df= }} "There is broad scientific consensus that Earth's climate is warming rapidly and at an accelerating rate. Human activities, primarily the burning of fossil fuels, are very likely (>90% probability) to be the main cause of this warming. Climate-sensitive changes in ecosystems are already being observed, and fundamental, potentially irreversible, ecological changes may occur in the coming decades. Conservative environmental estimates of the impact of climate changes that are already in process indicate that they will result in numerous health effects to children.  Anticipated direct health consequences of climate change include injury and death from extreme weather events and natural disasters, increases in climate-sensitive infectious diseases, increases in air pollution–related illness, and more heat-related, potentially fatal, illness. Within all of these categories, children have increased vulnerability compared with other groups."</ref>

<ref name="aapg">[http://dpa.aapg.org/gac/statements/climatechange.pdf AAPG Position Statement: Climate Change] from dpa.aapg.org</ref>

<ref name="aapg14">{{cite web|url=http://www.aapg.org/explorer/president/2007/03mar.cfm |title=Climate :03:2007 EXPLORER |publisher=Aapg.org |accessdate=2012-07-30}}</ref>

<ref name="aapg19">[http://dpa.aapg.org/gac/statements/climatechange.pdf AAPG ''Climate Change'' June 2007]</ref>

<ref name="AAWV ''Position Statement on Climate Change, Wildlife Diseases, and Wildlife Health''">{{citation |url=http://google.com/search?q=cache:IeEiaoU5hZAJ:www.aawv.net/AAWVPositionClimateChangeFinal.doc+AAWV+Position+Statements+wildlife+diseases+and+wildlife+health&hl=en&ct=clnk&cd=1&gl=us |title=AAWV ''Position Statement on Climate Change, Wildlife Diseases, and Wildlife Health''}} "There is widespread scientific agreement that the world's climate is changing and that the weight of evidence demonstrates that anthropogenic factors have and will continue to contribute significantly to global warming and climate change. It is anticipated that continuing changes to the climate will have serious negative impacts on public, animal and ecosystem health due to [[Earth:Extreme weather|extreme weather]] events, changing disease transmission dynamics, emerging and re-emerging diseases, and alterations to [[Earth:Habitat|habitat]] and ecological systems that are essential to [[Biology:Wildlife conservation|wildlife conservation]]. Furthermore, there is increasing recognition of the inter-relationships of human, domestic animal, wildlife, and ecosystem health as illustrated by the fact the majority of recent emerging diseases have a wildlife origin."</ref>

<ref name="ACPM Policy Statement ''Abrupt Climate Change and Public Health Implications''">{{citation |url=http://www.acpm.org/2006-002(C).htm |title=ACPM Policy Statement ''Abrupt Climate Change and Public Health Implications'' |year=2006 |access-date=2008-11-21 |archive-url=https://web.archive.org/web/20071107145339/https://www.acpm.org/2006-002(C).htm |archive-date=2007-11-07 |dead-url=yes |df= }} "The American College of Preventive Medicine (ACPM) accept the position that global warming and climate change is occurring, that there is potential for abrupt climate change, and that human practices that increase greenhouse gases exacerbate the problem, and that the public health consequences may be severe."</ref>

<!--ref name="agiweb">{{cite web|url=http://www.agiweb.org/gapac/climate_statement.html |title=AGI Statement on Global Climate Change |publisher=Agiweb.org |accessdate=2012-07-30}}</ref-->

<ref name="agu">{{cite web|url=http://www.agu.org/sci_pol/positions/climate_change2008.shtml |title=AGU Position Statement: Human Impacts on Climate |publisher=Agu.org |accessdate=2012-07-30}}</ref>

<ref name="agu13">{{cite web|url=http://www.agu.org/fora/eos/pdfs/2006EO360008.pdf|title=AGU - American Geophysical Union|website=AGU}}</ref>

<ref name="AIP science policy document.">{{citation |url=http://www.aip.org.au/scipolicy/Science%20Policy.pdf |title=AIP science policy document. |year=2005}} "Policy: The AIP supports a reduction of the green house gas emissions that are leading to increased global temperatures, and encourages research that works towards this goal.  Reason: Research in Australia and overseas shows that an increase in global temperature will adversely affect the Earth's climate patterns. The melting of the polar ice caps, combined with thermal expansion, will lead to rises in sea levels that may impact adversely on our coastal cities. The impact of these changes on [[Biology:Biodiversity|biodiversity]] will fundamentally change the [[Earth:Ecology|ecology]] of Earth."</ref>

<ref name="AIBS Position Statements">{{citation |url=http://www.aibs.org/position-statements |title=AIBS Position Statements}} "Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver."</ref>

<!--ref name="aipg">{{cite web |title=American Geological Institute Climate Statement |url=http://www.agiweb.org/gapac/climate_statement.html |archive-url=https://archive.is/20120717013914/http://www.agiweb.org/gapac/climate_statement.html |dead-url=yes |archive-date=17 July 2012 |date=12 Feb 1999 |accessdate=July 2012 |df= }}</ref-->

<!--ref name="aipg16">[http://www.aipg.org/StaticContent/anonymous/state_and_federal/Climate%20Change%20Letters.pdf AIPG Climate Change Letters sent to U.S. Government Officials]</ref-->

<ref name="AMA ''Climate Change and Human Health — 2004''">{{citation |url=https://fed.ama.com.au/cms/web.nsf/doc/WOOD-5ZD6BT |title=AMA ''Climate Change and Human Health — 2004'' |year=2004 }}{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }} They recommend policies "to mitigate the possible consequential health effects of climate change through improved energy efficiency, clean energy production and other emission reduction steps."</ref>

<ref name="aipg17">{{cite web |title=The Professional Geologist publications |url=http://www.aipg.org/Publications/TPGPublic.html |accessdate=2012-07-30 |archiveurl=https://web.archive.org/web/20120305085445/http://www.aipg.org/Publications/TPGPublic.html |archivedate=2012-03-05}}</ref>

<ref name="amap">{{cite web|url=http://amap.no/acia/ |title=ACIA Display |publisher=Amap.no |accessdate=2012-07-30}}</ref>

<ref name="AMA ''Climate Change and Human Health'' — 2004. Revised 2008.">{{citation |url=http://www.ama.com.au/node/4442 |title=AMA ''Climate Change and Human Health'' — 2004. Revised 2008. |year=2008 |deadurl=yes |archiveurl=https://web.archive.org/web/20090216083701/http://ama.com.au/node/4442 |archivedate=2009-02-16 |df= }} "The world's climate – our life-support system – is being altered in ways that are likely to pose significant direct and indirect challenges to health. While ‘climate change’ can be due to natural forces or human activity, there is now substantial evidence to indicate that human activity – and specifically increased greenhouse gas (GHGs) emissions – is a key factor in the pace and extent of global temperature increases.  Health impacts of climate change include the direct impacts of extreme events such as storms, floods, [[Earth:Heat wave|heatwaves]] and fires and the indirect effects of longer-term changes, such as drought, changes to the [[Earth:Food security|food]] and water supply, resource conflicts and population shifts.  Increases in average temperatures mean that alterations in the geographic range and seasonality of certain infections and diseases (including vector-borne diseases such as [[Medicine:Malaria|malaria]], [[Medicine:Dengue fever|dengue fever]], [[Medicine:Ross River virus|Ross River virus]] and food-borne infections such as [[Medicine:Salmonellosis|Salmonellosis]]) may be among the first detectable impacts of climate change on human health.  Human health is ultimately dependent on the health of the planet and its ecosystem. The AMA believes that measures which mitigate climate change will also benefit public health. Reducing GHGs should therefore be seen as a public health priority."</ref>

<ref name="American Chemical Society ''Global Climate Change''">{{citation |url=http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_SUPERARTICLE&node_id=1907&use_sec=false&sec_url_var=region1&__uuid=0cbd57b5-5766-456d-800b-680b88c1c8bf |title=American Chemical Society ''Global Climate Change'' }} "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.  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)."</ref>

<ref name="American Institute of Physics Statement supporting AGU statement on human-induced climate change">{{citation |url=http://www.aip.org/fyi/2004/042.html |title=American Institute of Physics Statement supporting AGU statement on human-induced climate change |year=2003}} "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."</ref>

<ref name="American Physical Society Climate Change Policy Statement">{{citation |url=http://www.aps.org/policy/statements/07_1.cfm |title=American Physical Society Climate Change Policy Statement |date=November 2007}} "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.  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.  Because the complexity of the climate makes accurate prediction difficult, the APS urges an enhanced effort to understand the effects of human activity on the Earth's climate, and to provide the technological options for meeting the climate challenge in the near and longer terms. The APS also urges governments, universities, national laboratories and its membership to support policies and actions that will reduce the emission of greenhouse gases.</ref>

<ref name="American Medical Association Policy Statement">{{citation |url=http://www.ama-assn.org/ama/pub/category/20275.html |title=American Medical Association Policy Statement |year=2008}} "Support the findings of the latest Intergovernmental Panel on Climate Change report, which states that the Earth is undergoing adverse global climate change and that these changes will negatively affect public health.  Support educating the medical community on the potential adverse public health effects of global climate change, including topics such as population displacement, flooding, infectious and vector-borne diseases, and healthy water supplies."</ref>

<ref name="ametsoc">{{cite web|url=http://www.ametsoc.org/policy/2012climatechange.html |title=AMS Information Statement on Climate Change |publisher=Ametsoc.org |date=2012-08-20 |accessdate=2012-08-27}}</ref>

<ref name="ametsoc22">{{cite web|url=http://www.ametsoc.org/POLICY/climatechangeresearch_2003.html |title=Climate Change Research: Issues for the Atmospheric and Related Sciences Adopted by the AMS Council 9 February 2003 |publisher=Ametsoc.org |date=2003-02-09 |accessdate=2012-07-30}}</ref>

<ref name="amos">{{cite web|url=http://www.amos.org.au/publications/cid/3/t/publications |title=Statement |publisher=AMOS |accessdate=2012-07-30}}</ref>

<ref name="apha">{{citation|url=http://www.apha.org/advocacy/policy/policysearch/default.htm?id=1351|title=American Public Health Association Policy Statement ‘’Addressing the Urgent Threat of Global Climate Change to Public Health and the Environment’’|year=2007|deadurl=yes|archiveurl=https://web.archive.org/web/20091231060829/http://www.apha.org/advocacy/policy/policysearch/default.htm?id=1351|archivedate=2009-12-31|df=}} "The long-term threat of global climate change to global health is extremely serious and the fourth IPCC report and other scientific literature demonstrate convincingly that anthropogenic GHG emissions are primarily responsible for this threat….US policy makers should immediately take necessary steps to reduce US emissions of GHGs, including carbon dioxide, to avert dangerous climate change."</ref>

<ref name="AQAonAAPG">{{cite journal|author=Julie Brigham-Grette |display-authors=0 |title=Petroleum Geologists' Award to Novelist Crichton Is Inappropriate|journal=Eos|volume=87|issue=36|page=364 |quote=The AAPG stands alone among scientific societies in its denial of human-induced effects on global warming.|url=http://onlinelibrary.wiley.com/doi/10.1029/2006EO360008/pdf |date=September 2006 |accessdate=2007-01-23|format=PDF|doi=10.1029/2006EO360008|bibcode=2006EOSTr..87..364B}}</ref>

<ref name="ASA Statement on Climate Change">{{citation |url=http://www.amstat.org/news/climatechange.cfm |title=ASA Statement on Climate Change |date=November 30, 2007}} "The ASA endorses the IPCC conclusions.... Over the course of four assessment reports, a small number of statisticians have served as authors or reviewers. Although this involvement is encouraging, it does not represent the full range of statistical expertise available. ASA recommends that more statisticians should become part of the IPCC process. Such participation would be mutually beneficial to the assessment of climate change and its impacts and also to the statistical community."</ref>

<ref name="Australian Coral Reef Society official letter">{{citation |url=http://www.australiancoralreefsociety.org/pdf/chadwick605a.pdf |title=Australian Coral Reef Society official letter |year=2006|archiveurl=https://web.archive.org/web/20060322170802/http://www.australiancoralreefsociety.org/pdf/chadwick605a.pdf|archivedate=22 March 2006}} Official communique regarding the Great Barrier Reef and the "world-wide decline in coral reefs through processes such as overfishing, runoff of nutrients from the land, [[Earth:Coral bleaching|coral bleaching]], global climate change, [[Biology:Ocean acidification|ocean acidification]], pollution", etc.:  There is almost total consensus among experts that the earth's climate is changing as a result of the build-up of greenhouse gases. The IPCC (involving over 3,000 of the world's experts) has come out with clear conclusions as to the reality of this phenomenon. One does not have to look further than the collective academy of scientists worldwide to see the string (of) statements on this worrying change to the earth's atmosphere.  There is broad scientific consensus that coral reefs are heavily affected by the activities of man and there are significant global influences that can make reefs more vulnerable such as global warming....It is highly likely that coral bleaching has been exacerbated by global warming."</ref>

<ref name="australiancoralreefsociety">{{cite web|url=http://www.australiancoralreefsociety.org/ |title=Australian Coral Reef Society |publisher=Australian Coral Reef Society |accessdate=2012-07-30}}</ref>

<ref name="autogenerated1">{{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 | accessdate=2012-08-28 | publisher=Network of African Science Academies |format=PDF}}</ref>

<ref name="australiancoralreefsociety24">[http://www.australiancoralreefsociety.org/pdf/chadwick605a.pdf Australian Coral Reef Society official letter] {{webarchive|url=https://web.archive.org/web/20060322170802/http://www.australiancoralreefsociety.org/pdf/chadwick605a.pdf |date=2006-03-22 }}, June 16, 2006</ref>

<ref name="Beyond the Ivory Tower: The Scientific Consensus on Climate Change">{{cite journal  | author=Naomi Oreskes  | date=December 3, 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 |format=PDF  | pmid=15576594}} ([http://sciencepolicy.colorado.edu/admin/publication_files/resource-1761-2005.32.pdf#search=%22%22Consensus%20About%20Climate%20Change%3F%22%20oreskes%22 see also for an exchange of letters to Science])</ref>

<ref name="cfcas">{{cite web|url=http://www.cfcas.org/LettertoPM19apr06e.pdf|title=CFCAS Letter to PM, November 25, 2005|publisher=}}</ref>

<ref name="Climate change statement from the Royal Society of New Zealand">{{cite web |first1=David |last1=Wratt |first2=James |last2=Renwick |url=http://www.royalsociety.org.nz/Site/news/media_releases/2008/clim0708.aspx |title=Climate change statement from the Royal Society of New Zealand |publisher=The Royal Society of New Zealand |date=2008-07-10 |accessdate=2010-01-20 |deadurl=yes |archiveurl=https://web.archive.org/web/20100522054524/http://www.royalsociety.org.nz/Site/news/media_releases/2008/clim0708.aspx |archivedate=2010-05-22 |df= }}</ref>

<ref name="cmos">[http://www.cmos.ca/ClimateChangeLetter_26Nov09.pdf Canadian Meteorological and Oceanographic Society Letter to Stephen Harper] (Updated, 2007)</ref>

<ref name="Editorial: The Science of Climate Change">{{cite journal |title=Editorial: The Science of Climate Change |journal=Science |volume=292 |issue=5520 |page=1261 |date=May 18, 2001 |doi= 10.1126/science.292.5520.1261|url=http://www.sciencemag.org/cgi/content/summary/292/5520/1261|last1=Statement |first1=J }}</ref>

<ref name="DZ_EOS_2009">{{cite journal|last1=Doran|first1=Peter T.|last2=Zimmerman|first2=Maggie Kendall|title=Examining the Scientific Consensus on Climate Change|journal=Eos|date=January 20, 2009|volume=90|issue=3|pages=22–23|doi=10.1029/2009EO030002|url=http://onlinelibrary.wiley.com/doi/10.1029/2009EO030002/abstract|language=en|issn=2324-9250|bibcode=2009EOSTr..90...22D}}</ref>

<ref name="euro-acad">[http://www.euro-acad.eu/downloads/memorandas/lets_be_honest_-_festplenum_03.03.07_-_final2.pdf European Academy of Sciences and Arts ''Let's Be Honest]</ref>

<ref name="EPS Position Paper ''Energy for the future: The Nuclear Option''">{{citation |url=http://archive.iupap.org/epspositionpaper.pdf |title=EPS Position Paper ''Energy for the future: The Nuclear Option'' |year=2007}} "The emission of anthropogenic greenhouse gases, among which carbon dioxide is the main contributor, has amplified the natural greenhouse effect and led to global warming. The main contribution stems from burning fossil fuels. A further increase will have decisive effects on life on earth. An energy cycle with the lowest possible {{CO2}} emission is called for wherever possible to combat climate change."</ref>

<ref name="eurogeologists">{{cite web|url=http://www.eurogeologists.de/index.php?section=home |title=EFG Website &#124; Home |publisher=Eurogeologists.de |date=2011-08-10 |accessdate=2012-07-30}}</ref>

<ref name="eurogeologists9">[http://www.eurogeologists.de/images/content/panels_of_experts/co2_geological_storage/CCS_position_paper.pdf EFG ''Carbon Capture and geological Storage '']</ref>

<ref name="European Science Foundation Position Paper ''Impacts of Climate Change on the European Marine and Coastal Environment — Ecosystems Approach''">{{citation |url=http://www.esf.org/publications/position-papers.html |title=European Science Foundation Position Paper ''Impacts of Climate Change on the European Marine and Coastal Environment — Ecosystems Approach'' |pages=7–10 |year=2007}} "There is now convincing evidence that since the industrial revolution, human activities, resulting in increasing concentrations of greenhouse gases have become a major agent of climate change. These greenhouse gases affect the global climate by retaining heat in the troposphere, thus raising the average temperature of the planet and altering global atmospheric circulation and precipitation patterns.  While on-going national and international actions to curtail and reduce greenhouse gas emissions are essential, the levels of greenhouse gases currently in the atmosphere, and their impact, are likely to persist for several decades. On-going and increased efforts to mitigate climate change through reduction in greenhouse gases are therefore crucial."</ref>

<ref name="Expert credibility in climate change">{{cite journal |last=Anderegg |first=William R L |last2=Prall |first2=James W. |last3=Harold |first3=Jacob |last4=Schneider |first4=Stephen H. |title=Expert credibility in climate change |journal=Proc. Natl. Acad. Sci. U.S.A. |year=2010 |url=http://www.pnas.org/content/early/2010/06/04/1003187107.full.pdf+html |pmid=20566872 |doi=10.1073/pnas.1003187107 |volume=107 |issue=27 |pages=12107–9 |pmc=2901439 |bibcode = 2010PNAS..10712107A }}</ref>

<ref name="foxnews">{{cite web|url=http://www.foxnews.com/story/0,2933,249659,00.html |title=U.N. Report: Global Warming Man-Made, Basically Unstoppable |publisher=Fox News |accessdate=2012-07-30}}</ref>

<ref name="FASTS Statement on Climate Change">{{citation |url=http://www.fasts.org/images/policy-discussion/statement-climate-change.pdf |title=FASTS Statement on Climate Change |year=2008}} "Global climate change is real and measurable. Since the start of the 20th century, the global mean surface temperature of the Earth has increased by more than 0.7°C and the rate of warming has been largest in the last 30 years.  Key vulnerabilities arising from climate change include water resources, food supply, health, coastal settlements, biodiversity and some key ecosystems such as coral reefs and alpine regions. As the atmospheric concentration of greenhouse gases increases, impacts become more severe and widespread. To reduce the global net economic, environmental and social losses in the face of these impacts, the policy objective must remain squarely focused on returning greenhouse gas concentrations to near pre-industrial levels through the reduction of emissions.  The spatial and temporal fingerprint of warming can be traced to increasing greenhouse gas concentrations in the atmosphere, which are a direct result of burning fossil fuels, broad-scale deforestation and other human activity."</ref>

<ref name="geolsoc">{{cite web |url=http://www.geolsoc.org.uk/gsl/views/policy_statements/page7426.html |title=Geological Society - Climate change: evidence from the geological record |publisher=Geolsoc.org.uk |accessdate=2012-07-30 |deadurl=yes |archiveurl=https://web.archive.org/web/20101110234112/http://www.geolsoc.org.uk/gsl/views/policy_statements/page7426.html |archivedate=2010-11-10 |df= }}</ref>

<!-- UNUSED <ref name="geoscience">{{cite web|author=billobrien.coml |url=http://geoscience.ca/_ARCHIVE_jan7_2011/climatechange.html |title=Canadian Federation of Earth Sciences (CFES) |publisher=Geoscience.ca |accessdate=2012-07-30}}</ref> -->

<ref name="geosociety">{{cite web|url=http://www.geosociety.org/positions/position10.htm |title=The Geological Society of America - Position Statement on Global Climate Change |publisher=Geosociety.org |accessdate=2012-07-30}}</ref>

<ref name="Global Environmental Change — Microbial Contributions, Microbial Solutions">{{citation |url=http://www.asm.org/images/docfilename/0000006005/globalwarming%5B1%5D.pdf |title=Global Environmental Change — Microbial Contributions, Microbial Solutions |date=May 2006 |format=PDF |publisher=American Society For Microbiology}} They recommended "reducing net anthropogenic {{CO2}} emissions to the atmosphere" and "minimizing anthropogenic disturbances of" atmospheric gases.  Carbon dioxide concentrations were relatively stable for the past 10,000 years but then began to increase rapidly about 150 years ago…as a result of fossil fuel consumption and land use change.  Of course, changes in atmospheric composition are but one component of global change, which also includes disturbances in the physical and chemical conditions of the oceans and land surface. Although global change has been a natural process throughout Earth's history, humans are responsible for substantially accelerating present-day changes. These changes may adversely affect human health and the [[Biology:Biosphere|biosphere]] on which we depend.  Outbreaks of a number of diseases, including [[Unsolved:Lyme disease|Lyme disease]], hantavirus infections, [[Medicine:Dengue fever|dengue fever]], [[Medicine:Bubonic plague|bubonic plague]], and [[Medicine:Cholera|cholera]], have been linked to climate change."</ref>

<ref name="globalchange">{{cite web|url=http://downloads.globalchange.gov/usimpacts/pdfs/climate-impacts-report.pdf|title=Downloads.globalchange.gov|publisher=}}</ref>

<ref name="IAGLR Fact Sheet ''The Great Lakes at a Crossroads: Preparing for a Changing Climate''">{{citation |url=http://www.iaglr.org/scipolicy/factsheets/iaglr_crossroads_climatechange.pdf |title=IAGLR Fact Sheet ''The Great Lakes at a Crossroads: Preparing for a Changing Climate'' |date=February 2009}} "While the Earth's climate has changed many times during the planet's history because of natural factors, including volcanic eruptions and changes in the Earth's orbit, never before have we observed the present rapid rise in temperature and carbon dioxide ({{CO2}}).  Human activities resulting from the industrial revolution have changed the chemical composition of the atmosphere....Deforestation is now the second largest contributor to global warming, after the burning of fossil fuels. These human activities have significantly increased the concentration of "greenhouse gases" in the atmosphere.  As the Earth's climate warms, we are seeing many changes: stronger, more destructive hurricanes; heavier rainfall; more disastrous flooding; more areas of the world experiencing severe drought; and more heat waves."</ref>

<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=2004-11-08|accessdate=2010-01-20 }}</ref>

<ref name="inqua">{{cite web|url=http://www.inqua.org/files/iscc.pdf|title=INQUA Statement On Climate Change.|publisher=}}</ref>

<ref name="interacademycouncil">{{cite web|url=http://www.interacademycouncil.net/CMS/3239.aspx |title=InterAcademy Council |publisher=InterAcademy Council |accessdate=2012-07-30}}</ref>

<ref name="interacademycouncil7">{{cite web|url=http://www.interacademycouncil.net/CMS/Reports/11840/11842.aspx |title=InterAcademy Council |publisher=InterAcademy Council |accessdate=2012-07-30}}</ref>

<ref name="interacademycouncil8">{{cite web|url=http://www.interacademycouncil.net/CMS/Reports/11840/11971/11979.aspx |title=InterAcademy Council |publisher=InterAcademy Council |accessdate=2012-07-30}}</ref>

<ref name="iob">{{citation |url=http://www.iob.org/general.asp?section=science_policy/policy_issues&article=climate_change.xml |title=Institute of Biology policy page ‘Climate Change’}}  "there is scientific agreement that the rapid global warming that has occurred in recent years is mostly anthropogenic, ''ie'' due to human activity."  As a consequence of global warming, they warn that a "rise in sea levels due to melting of ice caps is expected to occur. Rises in temperature will have complex and frequently localised effects on weather, but an overall increase in extreme weather conditions and changes in precipitation patterns are probable, resulting in flooding and drought. The spread of tropical diseases is also expected."   Subsequently, the Institute of Biology advocates policies to reduce "greenhouse gas emissions, as we feel that the consequences of climate change are likely to be severe."</ref>

<ref name="ipcc1">IPCC, [http://www.ipcc.ch/publications_and_data/ar4/syr/en/main.html Synthesis Report], [http://www.ipcc.ch/publications_and_data/ar4/syr/en/mains2-4.html Section 2.4: Attribution of climate change], in {{Harvnb|IPCC AR4 SYR|2007}}."It is likely that increases in GHG concentrations alone would have caused more warming than observed because volcanic and anthropogenic aerosols have offset some warming that would otherwise have taken place."</ref>

<ref name="iugg">{{cite web|url=http://www.iugg.org/resolutions/perugia07.pdf|title=IUGG Resolution 6|publisher=}}</ref>

<ref name="IPENZ Informatory Note, ''Climate Change and the greenhouse effect''">{{citation |url=http://www.ipenz.org.nz/ipenz/forms/pdfs/Info_Note_6.pdf |title=IPENZ Informatory Note, ''Climate Change and the greenhouse effect'' |date=October 2001}} "Human activities have increased the concentration of these atmospheric greenhouse gases, and although the changes are relatively small, the equilibrium maintained by the atmosphere is delicate, and so the effect of these changes is significant. The world's most important greenhouse gas is carbon dioxide, a by-product of the burning of fossil fuels. Since the time of the Industrial Revolution about 200 years ago, the concentration of carbon dioxide in the atmosphere has increased from about 280 parts per million to 370 parts per million, an increase of around 30%.  On the basis of available data, climate scientists are now projecting an average global temperature rise over this century of 2.0 to 4.5°C. This compared with 0.6°C over the previous century – about a 500% increase... This could lead to changing, and for all emissions scenarios more unpredictable, weather patterns around the world, less frost days, more extreme events (droughts and storm or flood disasters), and warmer sea temperatures and melting glaciers causing sea levels to rise.  ... Professional engineers commonly deal with risk, and frequently have to make judgments based on incomplete data. The available evidence suggests very strongly that human activities have already begun to make significant changes to the earth's climate, and that the long-term risk of delaying action is greater than the cost of avoiding/minimising the risk."</ref>

<ref name="Letter to US Senators">{{citation |url=http://www.aaas.org/news/releases/2009/media/1021climate_letter.pdf |title=Letter to US Senators |date=October 2009}}</ref>

<ref name="journalistsresource">{{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="nagt">{{cite web|url=http://www.nagt.org/index.html|title=NAGT|website=NAGT}}</ref>

<ref name="nagt11">{{cite web|url=http://nagt.org/nagt/organization/ps-climate.html|title=Page Not Found|website=SERC}}</ref>

<ref name="nationalacademies">[http://www.nationalacademies.org/onpi/06072005.pdf Joint science academies’ statement: Global response to climate change], 2005</ref>

<ref name="nas">
{{cite book
 | year=2008
 | title=Understanding and Responding to Climate Change. A brochure prepared by the US National Research Council (US NRC)
 | publisher=US National Academy of Sciences
 | author=US NRC
 | url=http://dels.nas.edu/resources/static-assets/materials-based-on-reports/booklets/climate_change_2008_final.pdf
 | location = Washington DC, USA
}}
</ref>

<ref name="nationalacademies5">{{cite web|url=http://www.nationalacademies.org/includes/climatechangestatement.pdf|title=2008 Joint Science Academies’ Statement|publisher=}}</ref>

<ref name="nationalacademies21">{{cite web|url=http://nationalacademies.org/onpi/06072005.pdf|title=Joint Science Academies' Statement|publisher=}}</ref>

<ref name="nationalacademies6">{{cite web|url=http://www.nationalacademies.org/includes/G8+5energy-climate09.pdf|title=2009 Joint Science Academies’ Statement|publisher=}}</ref>

<ref name="nytimes">{{cite news|url=https://www.nytimes.com/2007/10/23/business/worldbusiness/23energy.html|title=Panel Urges Global Shift on Sources of Energy|first=Andrew C.|last=Revkin|date=23 October 2007|publisher=|via=NYTimes.com}}</ref>

<ref name="On the Climate Change Beat, Doubt Gives Way to Certainty">{{cite news |url=https://www.nytimes.com/2007/02/06/science/earth/06clim.html?pagewanted=1&ei=5088&en=53862c0cdf77d1c0&ex=1328418000&partner=rssnyt&emc=rss |title=On the Climate Change Beat, Doubt Gives Way to Certainty |newspaper=New York Times |accessdate=2010-08-28 |first=William K. |last= Stevens |quote=The Intergovernmental Panel on Climate Change said the likelihood was 90 percent to 99 percent that emissions of heat-trapping greenhouse gases like carbon dioxide, spewed from tailpipes and smokestacks, were the dominant cause of the observed warming of the last 50 years. In the panel's parlance, this level of certainty is labeled "very likely." Only rarely does scientific odds-making provide a more definite answer than that, at least in this branch of science, and it describes the endpoint, so far, of a progression. | date=2007-02-06 }}</ref>

<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 |ref=harv |chapterurl=https://books.google.com/books?id=PXJIqCkb7YIC&lpg=PP1&pg=PA65#v=onepage&q&f=false |url=https://books.google.com/books?id=PXJIqCkb7YIC&printsec=frontcover#v=onepage&q&f=false}}</ref>

<ref name="Oreskes07p68">{{harvnb|Oreskes|2007|p=[https://books.google.com/books?id=PXJIqCkb7YIC&lpg=PP1&pg=PA68#v=onepage&q&f=false 68]}}</ref>

<ref name="pik-potsdam">{{cite web|url=http://www.pik-potsdam.de/aktuelles/nachrichten/dateien/G8_Academies%20Declaration.pdf|title=2007 Joint Science Academies' Statement|publisher=}}</ref>

<ref name="Policy Statement, Climate Change and Energy">{{citation |url=http://www.engineersaustralia.org.au/representation/policy-positions/climate-change.cfm | title=Policy Statement, Climate Change and Energy |date=February 2007}} "Engineers Australia 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 name="Prediction' or 'Projection; The nomenclature of climate science">{{cite journal |author=Bray, D.|author2=von Storch H.  |year=2009 |title=Prediction' or 'Projection; The nomenclature of climate science |journal=Science Communication |volume=30 |pages=534–543 |doi=10.1177/1075547009333698 |issue=4}}</ref>

<ref name="rosenthal">{{cite news |url=https://www.nytimes.com/2007/02/03/science/earth/03climate.html?ex=1328158800&en=61f42312221df544&ei=5090&partner=rssuserland&emc=rss%3Cbr%20/%3E |title=Science Panel Calls Global Warming ‘Unequivocal’ |newspaper=New York Times |first=Elisabeth |last=Rosenthal |first2= Andrew C. |last2=Revkin |date=2007-02-03 |quote=the leading international network of climate scientists has concluded for the first time that global warming is 'unequivocal' and that human activity is the main driver, 'very likely' causing most of the rise in temperatures since 1950 |accessdate=2010-08-28}}</ref>

<ref name="rmets">{{cite web|url=http://www.rmets.org/news/detail.php?ID=332|title=News - Royal Meteorological Society|website=www.rmets.org}}</ref>

<ref name="RS-CC">{{cite web |url=http://royalsociety.org/Climate-Change/ |title=New guide to science of climate change |publisher=The Royal Society |accessdate=9 June 2010}}</ref>

<ref name="SAF ''Forest Management and Climate Change ''">{{citation |url=http://www.safnet.org/policyandpresspsst/climate_change_expires12-8-2013.pdf |title=SAF ''Forest Management and Climate Change '' |year=2008}} "Forests are shaped by climate....Changes in temperature and precipitation regimes therefore have the potential to dramatically affect forests nationwide. There is growing evidence that our climate is changing. The changes in temperature have been associated with increasing concentrations of atmospheric carbon dioxide ({{CO2}}) and other GHGs in the atmosphere."</ref>

<ref name="Society to review climate message">{{cite news |url=http://news.bbc.co.uk/2/hi/science_and_environment/10178124.stm |title=Society to review climate message |last=Harrabin |first=Roger |publisher=BBC News |date=27 May 2010 |accessdate=9 June 2010}}</ref>

<ref name="SAF ''Forest Offset Projects in a Carbon Trading System''">{{citation |url=http://www.safnet.org/policyandpresspsst/offset_projections_expires12-8-2013.pdf |title=SAF ''Forest Offset Projects in a Carbon Trading System'' |year=2008}} "Forests play a significant role in offsetting {{CO2}} emissions, the primary anthropogenic GHG."</ref>

<ref name="Some excitable climate-change deniers just don't understand what science is">{{cite web |url=http://www.montrealgazette.com/news/Some+excitable+climate+change+deniersjust+understand+what+science/3128015/story.html |title=Some excitable climate-change deniers just don't understand what science is |last=Gardner |first=Dan |publisher=Montreal Gazette |date=8 June 2010 |accessdate=9 June 2010 | archiveurl=https://web.archive.org/web/20100611083407/http://www.montrealgazette.com/news/Some+excitable+climate+change+deniersjust+understand+what+science/3128015/story.html | archivedate=11 June 2010}}</ref>

<ref name="soils">{{cite web|url=https://www.soils.org/files/science-policy/asa-cssa-sssa-climate-change-policy-statement.pdf|title=ASA, CSSA, and SSSA Position Statement on Climate Change|publisher=}}</ref>

<ref name="Stanowisko Zgromadzenia Ogólnego PAN z dnia 13 grudnia 2007 r">{{cite web|url=http://www.aktualnosci.pan.pl/images/stories/pliki/stanowiska_opinie/2008/stanowisko_pan_131207.pdf|title=Stanowisko Zgromadzenia Ogólnego PAN z dnia 13 grudnia 2007 r|publisher=Polish Academy of Sciences|language=Polish|accessdate=2009-06-16}} ''Note'': As of 16 June 2009, PAS has not issued this statement in English, all citations have been translated from Polish.</ref>

<!--ref name="stateclimate">http://www.stateclimate.org/publications/default.php?content=policies</ref-->

<!--ref name="stateclimate15">[http://www.stateclimate.org/publications/files/aascclimatepolicy.pdf Policy Statement on Climate Variability and Change] by the American Association of State Climatologists (AASC)</ref-->

<ref name="AR4-warming-unequivocal">"Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level." IPCC, [http://www.ipcc.ch/publications_and_data/ar4/syr/en/main.html Synthesis Report], [http://www.ipcc.ch/publications_and_data/ar4/syr/en/mains1.html Section 1.1: Observations of climate change], in {{Harvnb|IPCC AR4 SYR|2007}}.</ref>

<ref name="Warming 'very likely' human-made">{{cite news |title=Warming 'very likely' human-made |url=http://news.bbc.co.uk/2/hi/science/nature/6321351.stm |work=BBC News |publisher=BBC |date=2007-02-01 |accessdate=2007-02-01 }}</ref>

<ref name="The Science of Climate Change">{{cite web|url=http://science.sciencemag.org/content/292/5520/1261%5D,|title=The Science of Climate Change|publisher=Science Magazine}}{{Dead link|date=August 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

<ref name="telegraph.co.uk">{{cite news| url=https://www.telegraph.co.uk/earth/earthnews/7778917/Royal-Society-to-publish-guide-on-climate-change-to-counter-claims-of-exaggeration.html | location=London | work=The Daily Telegraph | title=Royal Society to publish guide on climate change to counter claims of 'exaggeration' | first=Louise | last=Gray | date=May 29, 2010}}</ref>

<ref name="www">{{cite web |url=http://www.egu.eu/statements/position-statement-of-the-divisions-of-atmospheric-and-climate-sciences-7-july-2005.html |title=Archived copy |accessdate=2011-04-28 |deadurl=yes |archiveurl=https://web.archive.org/web/20111005070752/http://www.egu.eu/statements/position-statement-of-the-divisions-of-atmospheric-and-climate-sciences-7-july-2005.html |archivedate=2011-10-05 |df= }}</ref>

<ref name="www10">{{cite web |url=http://www.egu.eu/statements/egu-position-statement-on-ocean-acidification.html |title=Archived copy |accessdate=2009-01-06 |deadurl=yes |archiveurl=https://web.archive.org/web/20090118162917/http://www.egu.eu/statements/egu-position-statement-on-ocean-acidification.html |archivedate=2009-01-18 |df= }}</ref>

<ref name="Wildlife Society ''Global Climate Change and Wildlife''">{{citation |url=http://joomla.wildlife.org/documents/positionstatements/35-Global%20Climate%20Change%20and%20Wildlife.pdf |title=Wildlife Society ''Global Climate Change and Wildlife'' |deadurl=yes |archiveurl=https://web.archive.org/web/20081127232217/http://joomla.wildlife.org/documents/positionstatements/35-Global%20Climate%20Change%20and%20Wildlife.pdf |archivedate=2008-11-27 |df= }} "Scientists throughout the world have concluded that climate research conducted in the past two decades definitively shows that rapid worldwide climate change occurred in the 20th century, and will likely continue to occur for decades to come. Although climates have varied dramatically since the Earth was formed, few scientists question the role of humans in exacerbating recent climate change through the emission of greenhouse gases. The critical issue is no longer "if" climate change is occurring, but rather how to address its effects on wildlife and wildlife habitats."  The statement goes on to assert that "evidence is accumulating that wildlife and wildlife habitats have been and will continue to be significantly affected by ongoing large-scale rapid climate change."  The statement concludes with a call for "reduction in anthropogenic (human-caused) sources of carbon dioxide and other greenhouse gas emissions contributing to global climate change and the conservation of {{CO2}}- consuming [[Earth:Photosynthesis|photosynthesizers]] (i.e., plants)."</ref>
<ref name="wfpha">{{citation |url=http://www.wfpha.org/Archives/01.22%20Global%20Climate%20Change.pdf |title=World Federation of Public Health Associations resolution "Global Climate Change" |year=2001 |deadurl=yes |archiveurl=https://web.archive.org/web/20081217173936/http://www.wfpha.org/Archives/01.22%20Global%20Climate%20Change.pdf |archivedate=2008-12-17 |df= }} "Noting the conclusions of the {{wipe|United Nations}}' Intergovernmental Panel on Climate Change (IPCC) and other climatologists that anthropogenic greenhouse gases, which contribute to global climate change, have substantially increased in atmospheric concentration beyond natural processes and have increased by 28 percent since the industrial revolution….Realizing that subsequent health effects from such perturbations in the climate system would likely include an increase in: heat-related mortality and morbidity; vector-borne infectious diseases,… water-borne diseases…(and) malnutrition from threatened agriculture….the World Federation of Public Health Associations…recommends precautionary primary preventive measures to avert climate change, including reduction of greenhouse gas emissions and preservation of greenhouse gas sinks through appropriate energy and land use policies, in view of the scale of potential health impacts...."</ref>

<ref name="WHO ''Protecting health from climate change''">{{citation |url=http://www.who.int/world-health-day/toolkit/report_web.pdf |title=WHO ''Protecting health from climate change'' |year=2008 |page=2 |accessdate=2009-04-18}}</ref>

<ref name="Statement supporting AGU statement on human-induced climate change">{{citation |url=http://www.aas.org/governance/council/resolutions.php#climate |title=Statement supporting AGU statement on human-induced climate change |publisher=American Astronomical Society |year=2004 |deadurl=yes |archiveurl=https://web.archive.org/web/20070507060001/http://www.aas.org/governance/council/resolutions.php#climate |archivedate=2007-05-07 |df= }} "In endorsing the "Human Impacts on Climate" statement [issued by the American Geophysical Union], 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."</ref>

<ref name="Survey Tracks Scientists' Growing Climate Concern">{{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=2008-04-23 |accessdate=2010-01-20 }}</ref>

<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|title= The Structure of Scientific Opinion on Climate Change|author1=Stephen J. Farnsworth |author2=S. Robert Lichter |date= October 27, 2011|publisher= International Journal of Public Opinion Research |accessdate= December 2, 2011 }}</ref>

<!--ref name="ams2012">http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-13-00091.1</ref-->
}}

<!-- The following sources are referred to using the harvnb template -->
* {{Citation
|year   = 2001
|author = Ipcc tar syr
|title  = Climate Change 2001: Synthesis Report
|series = Contribution of Working Groups I, II, and III to the [[Earth:IPCC Third Assessment Report|Third Assessment Report]] of the Intergovernmental Panel on Climate Change
|editor1=Watson, R. T. |editor2=the Core Writing Team |publisher = Cambridge University Press
|url =  http://www.ipcc.ch/ipccreports/tar/vol4/english/index.htm
|isbn = 0-521-80770-0 
}} (pb: {{ISBNT|0-521-01507-3}}).
* {{Citation
|year   = 2007
|author = Ipcc ar4 wg2
|title  = Climate Change 2007: Impacts, Adaptation and Vulnerability
|series = Contribution of Working Group II to the [[Earth:IPCC Fourth Assessment Report|Fourth Assessment Report]] of the Intergovernmental Panel on Climate Change
|editor1=Parry, M.L. |editor2=Canziani, O.F. |editor3=Palutikof, J.P. |editor4=van der Linden, P.J. |editor5=Hanson, C.E. |publisher = Cambridge University Press
|url  = http://www.ipcc.ch/publications_and_data/ar4/wg2/en/contents.html
|isbn = 978-0-521-88010-7
}} (pb: {{ISBNT|978-0-521-70597-4}}).
* {{Citation
|year   = 2007
|author = Ipcc ar4 wg3
|title  = Climate Change 2007: Mitigation of Climate Change
|series = Contribution of Working Group III to the [[Earth:IPCC Fourth Assessment Report|Fourth Assessment Report]] of the Intergovernmental Panel on Climate Change
|editor1=Metz, B. |editor2=Davidson, O.R. |editor3=Bosch, P.R. |editor4=Dave, R. |editor5=Meyer, L.A. |publisher = Cambridge University Press
|url  = http://www.ipcc.ch/publications_and_data/ar4/wg3/en/contents.html
|isbn = 978-0-521-88011-4
}} (pb: {{ISBNT|978-0-521-70598-1}}).
* {{Citation
| year   = 2007
| author = Ipcc ar4 syr
| title  = Climate Change 2007: Synthesis Report (SYR)
| series = Contribution of Working Groups I, II and III to the [[Earth:IPCC Fourth Assessment Report|Fourth Assessment Report]] (AR4) of the Intergovernmental Panel on Climate Change
|editor1=Core Writing Team |editor2=Pachauri, R.K |editor3=Reisinger, A. | publisher = IPCC
| location=[[Place:Geneva|Geneva]], {{wipe|Switzerland}}
| url  = http://www.ipcc.ch/publications_and_data/ar4/syr/en/contents.html
| isbn = 92-9169-122-4
}}.
* {{citation
 | year=2001
 | title=Climate Change Science: An Analysis of Some Key Questions. A report by the Committee on the Science of Climate Change, US National Research Council (NRC)
 | publisher=National Academy Press
 | location=Washington, D.C., USA
 | author=US NRC
 | url=http://www.nap.edu/openbook.php?record_id=10139&page=1
 | isbn=0-309-07574-2
 | archiveurl= https://web.archive.org/web/20110605132107/http://www.nap.edu/openbook.php?record_id=10139&page=1
 | archivedate= 5 June 2011 <!--DASHBot-->| deadurl= no
}}

{{global warming}}

[[Category:Climate change skepticism and denial]]
[[Category:Climate change assessment and attribution]]

{{Sourceattribution|Scientific opinion on climate change|1}}