Scientific opinion on climate change

This article is about scientific consensus on the current climate change. For public perception and controversy, see Public opinion on climate change and Global warming controversy.
refer to caption
Global mean land-ocean temperature change since 1880, relative to the 1951–1980 mean. The black line is the annual mean and the red line is the 5-year running mean. Source: NASA GISS
The temperature record of the past 2000 years from several different proxy methods.

The scientific opinion on climate change is the overall judgment among scientists regarding the extent to which global warming is occurring, its causes, and its probable consequences. This scientific opinion is expressed in synthesis reports, by scientific bodies of national or international standing, and by surveys of opinion among climate scientists. Individual scientists, universities, and laboratories contribute to the overall scientific opinion via their peer-reviewed publications, and the areas of collective agreement and relative certainty are summarised in these respected reports and surveys.[1]

The scientific consensus is that the Earth's climate system is unequivocally warming, and that it is extremely likely (meaning 95% probability or higher) that this warming is predominantly caused by humans. It is likely that this mainly arises from increased concentrations of greenhouse gases in the atmosphere, such as from deforestation and the burning of fossil fuels, partially offset by human caused increases in aerosols; natural changes had little effect.[2][3][4][5]

National and international science academies and scientific societies have assessed current scientific opinion on global warming. These assessments are generally consistent with the conclusions of the Intergovernmental Panel on Climate Change. The IPCC Fourth Assessment Report stated that:

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.[11][12]

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 American Association of Petroleum Geologists,[13] which in 2007[14] updated its statement to its current non-committal position.[15] 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.[16]

Intergovernmental Panel on Climate Change (IPCC) 2014

The IPCC Fifth Assessment Report Summary for Policymakers stated that warming of the climate system is 'unequivocal' with changes unprecedented over decades to millennia, including warming of the atmosphere and oceans, loss of snow and ice, and sea level rise. Greenhouse gas emissions, driven largely by economic and population growth, have led to greenhouse gas concentrations that are unprecedented in at least 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.[17]

It said that

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.[17]

Reporting on the publication of the report, The Guardian said that

In the end it all boils down to risk management. The stronger our efforts to reduce greenhouse gas emissions, 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.[18]

The New York Times reported that

In Washington, President Obama's science adviser, 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."[19]

It went on to say that Ban Ki-moon, the United Nations secretary general, had declared his intention to call a meeting of heads of state in 2014 to develop such a treaty. The last such meeting, in Copenhagen in 2009, the NY Times reported, had ended in disarray.[19]

Intergovernmental Panel on Climate Change (IPCC) 2007

In February 2007, the IPCC released a summary of the forthcoming 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.[20]

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".[21]

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.".[22]

The Associated Press summarized the position on sea level rise:

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.[23]

U.S. Global Change Research Program

Formerly: Climate Change Science Program

The U.S. Global Change Research Program reported in June 2009[24] that:

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:

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 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 7 °F (3.9 °C). Some of the changes have been faster than previous assessments had suggested.

Arctic Climate Impact Assessment

In 2004, the intergovernmental Arctic Council and the non-governmental International Arctic Science Committee released the synthesis report of the Arctic Climate Impact Assessment:[25]

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.[26]


There is an extensive discussion in the scientific literature on what policies might be effective in responding to climate change.[27] Some scientific bodies have recommended specific policies to governments (refer to the later sections of the article).[28] The natural and social sciences can play a role in informing an effective response to climate change.[11] However, policy decisions may require value judgements.[11] For example, the US National Research Council has commented:[12]

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.

This article mostly focuses on the views of natural scientists. However, social scientists,[27] medical experts,[29] engineers[27] and philosophers[30] have also commented on climate change science and policies. Climate change policy is discussed in several articles: climate change mitigation, climate change adaptation, climate engineering, politics of global warming, climate ethics, and 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.


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
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:

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.[37]

Additional national science academy and society statements
International science academies

Physical and chemical sciences

Earth sciences

American Geophysical Union

The American Geophysical Union (AGU) adopted a statement on Climate Change and Greenhouse Gases in 1998.[59] A new statement, adopted by the society in 2003, revised in 2007,[60] and revised and expanded in 2013,[61] affirms that rising levels of greenhouse gases have caused and will continue to cause the global surface temperature to be warmer:

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°C (1.5°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 Soil Science Society of America (SSSA) issued a joint position statement on climate change as it relates to agriculture:

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.[62]

European Federation of Geologists

In 2008, the European Federation of Geologists[63] (EFG) issued the position paper Carbon Capture and geological Storage :

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.[64]

European Geosciences Union

In 2005, the Divisions of Atmospheric and Climate Sciences of the European Geosciences Union (EGU) issued a position statement in support of the joint science academies’ statement on global response to climate change. The statement refers to the Intergovernmental Panel on Climate Change (IPCC), as "the main representative of the global scientific community", and asserts that the IPCC

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.[65]

Additionally, in 2008, the EGU issued a position statement on 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."[66]

Geological Society of America

In 2006, the Geological Society of America adopted a position statement on global climate change. It amended this position on April 20, 2010 with more explicit comments on need for CO2 reduction.

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.[67]
Geological Society of London

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

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.[68]

International Union of Geodesy and Geophysics

In July 2007, the 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.”[69]

National Association of Geoscience Teachers

In July 2009, the National Association of Geoscience Teachers[70] (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":

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.[71]

Meteorology and oceanography

American Meteorological Society

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

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.[72]

Australian Meteorological and Oceanographic Society

The Australian Meteorological and Oceanographic Society has issued a Statement on Climate Change, wherein they conclude:

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 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.”[73]
Canadian Foundation for Climate and Atmospheric Sciences

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

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.[74]
Canadian Meteorological and Oceanographic Society

In November 2009, a letter to the Canadian Parliament by The Canadian Meteorological and Oceanographic Society states:

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.[75]
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.”[76]

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 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.” [77]

American Quaternary Association

The American Quaternary Association (AMQUA) has stated

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.[78]
International Union for Quaternary Research

The statement on climate change issued by the 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.

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.[79]

Biology and life sciences

Life science organizations have outlined the dangers climate change pose to wildlife.

Human health

A number of health organizations have warned about the numerous negative health effects of global warming

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.
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 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.


A number of other national scientific societies have also endorsed the opinion of the IPCC:


American Association of Petroleum Geologists

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

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.[104]

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.[13] Explaining the plan for a revision, AAPG president Lee Billingsly wrote in March 2007:

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.[105]

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

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.[106]

American Institute of Professional Geologists

In 2009, the American Institute of Professional Geologists[107] (AIPG) sent a statement to President Barack Obama and other US government officials:

The geological professionals in AIPG recognize that climate change is occurring and has the potential to yield catastrophic impacts if humanity is not prepared to address those impacts. It is also recognized that climate change will occur regardless of the cause. The sooner a defensible scientific understanding can be developed, the better equipped humanity will be to develop economically viable and technically effective methods to support the needs of society.[108]

Concerned that the original statement issued in March 2009 was too ambiguous, AIPG’s National Executive Committee approved a revised position statement issued in January 2010:

The geological professionals in AIPG recognize that climate change is occurring regardless of cause. AIPG supports continued research into all forces driving climate change.[109]

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.[110] The Executive Director said that “the question of anthropogenicity of climate change is contentious.”[111]

Canadian Federation of Earth Sciences

The science of global climate change is still evolving and our understanding of this vital Earth system is not as developed as is the case for other Earth systems such as plate tectonics. What is known with certainty is that regardless of the causes, our global climate will continue to change for the foreseeable future... The level of CO2 in our atmosphere is now greater than at any time in the past 500,000 years; there will be consequences for our global climate and natural systems as a result.[112]

Geological Society of Australia

After a long and extensive and extended consultation with society members, the GSA executive committee has decided not to proceed with a climate change position statement.[113]


Since 2007, when the American Association of Petroleum Geologists released a revised statement,[14] no scientific body of national or international scientists rejects the findings of human-induced effects on climate change.[13][15]

Surveys of scientists and scientific literature

Summary of opinions from climate and earth scientists regarding climate change. Click to see a more detailed summary of the sources.
Seven papers into man-made global warming consensus, from 2004–2015, by Naomi Oreskes,[114] Peter Doran,[115] William Anderegg,[116] Bart Verheggen,[117] Neil Stenhouse,[118] J. Stuart Carlton,[119] and John Cook.[120][121]
Peer-reviewed research rejecting man-made global warming is almost non-existent as of 2013-14.[122]

Various surveys have been conducted to evaluate scientific opinion on 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 Naomi Oreskes summarized a study of the scientific literature on climate change.[114] She analyzed 928 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, 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 American Geophysical Union for the Statistical Assessment Service (STATS) at 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.[123][124][125][126]

Dennis Bray and Hans von Storch conducted a survey in August 2008 of 2058 climate scientists from 34 different countries.[127] 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.[128]

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 Peter Doran and Maggie Kendall Zimmerman at 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 meteorologists were among the biggest doubters, with only 47 percent and 64 percent, respectively, believing in significant human involvement. The authors summarised the findings:

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.[115]

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:

(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.[116]

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".[120]

James L. Powell, a former member of the National Science Board and current executive director of the 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.[129] 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.[130] 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.[122]

Scientific consensus

A question that frequently arises in popular discussion of climate change is whether there is a scientific consensus on climate change.[1] Several scientific organizations have explicitly used the term "consensus" in their statements:

See also


  1. 1 2 Oreskes, Naomi (2007). "The Scientific Consensus on Climate Change: How Do We Know We're Not Wrong?". In DiMento, Joseph F. C.; Doughman, Pamela M. Climate Change: What It Means for Us, Our Children, and Our Grandchildren. MIT Press. pp. 65–66. ISBN 978-0-262-54193-0.
  2. "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, Synthesis Report, Section 1.1: Observations of climate change, in IPCC AR4 SYR 2007.
  3. IPCC, "Summary for Policymakers" (PDF), Detection and Attribution of Climate Change, «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 IPCC AR5 WG1 2013.
  4. IPCC, Synthesis Report, Section 2.4: Attribution of climate change, in 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."
  5. [Notes-SciPanel] America's Climate Choices: Panel on Advancing the Science of Climate Change; National Research Council (2010). Advancing the Science of Climate Change. Washington, D.C.: The National Academies Press. ISBN 0-309-14588-0. (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.
  6. "Summary for Policymakers", 1. Observed changes in climate and their effects, in IPCC AR4 SYR 2007
  7. "Summary for Policymakers", 2. Causes of change, in IPCC AR4 SYR 2007
  8. 1 2 3 Parry, M.L.; et al., "Technical summary", Industry, settlement and society, in: Box TS.5. The main projected impacts for systems and sectors, in IPCC AR4 WG2 2007
  9. IPCC, "Summary for Policymakers", Magnitudes of impact, in IPCC AR4 WG2 2007
  10. "Synthesis report", Ecosystems, in: Sec 3.3.1 Impacts on systems and sectors, in IPCC AR4 SYR 2007
  11. 1 2 3 "Question 1", 1.1, in IPCC TAR SYR 2001, p. 38
  12. 1 2 Summary, in US NRC 2001, p. 4
  13. 1 2 3 Julie Brigham-Grette; et al. (September 2006). "Petroleum Geologists' Award to Novelist Crichton Is Inappropriate" (PDF). Eos. 87 (36): 364. Bibcode:2006EOSTr..87..364B. doi:10.1029/2006EO360008. Retrieved 2007-01-23. The AAPG stands alone among scientific societies in its denial of human-induced effects on global warming.
  14. 1 2 AAPG Climate Change June 2007
  15. 1 2 Oreskes 2007, p. 68
  16. Ogden, Aynslie & Cohen, Stewart (2002). "Integration and Synthesis: Assessing Climate Change Impacts in Northern Canada" (PDF). Retrieved 2009-04-12.
  17. 1 2 "Climate Change 2014 Synthesis Report Summary for Policymakers" (PDF). IPCC. Retrieved 1 August 2015.
  18. Nuccitelli, Dana (31 March 2014). "IPCC report warns of future climate change risks, but is spun by contrarians". The Guardian. Retrieved 1 August 2015.
  19. 1 2 "U.N. Climate Panel Endorses Ceiling on Global Emissions". The New York Times. 27 September 2013. Retrieved 1 August 2015.
  20. "Warming 'very likely' human-made". BBC News. BBC. 2007-02-01. Retrieved 2007-02-01.
  21. Rosenthal, Elisabeth; Revkin, Andrew C. (2007-02-03). "Science Panel Calls Global Warming 'Unequivocal'". New York Times. Retrieved 2010-08-28. 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
  22. Stevens, William K. (2007-02-06). "On the Climate Change Beat, Doubt Gives Way to Certainty". New York Times. Retrieved 2010-08-28. 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.
  23. "U.N. Report: Global Warming Man-Made, Basically Unstoppable". Fox News. Retrieved 2012-07-30.
  25. "Impacts of a Warming Arctic: Arctic Climate Impact Assessment New Scientific Consensus: Arctic Is Warming Rapidly". UNEP/GRID-Arendal. 2004-11-08. Retrieved 2010-01-20.
  26. "ACIA Display". Retrieved 2012-07-30.
  27. 1 2 3 The literature has been assessed by the IPCC, e.g., see:
  28. 1 2 2009 Joint Science Academies’ Statement
  29. Doha Declaration on Climate, Health and Wellbeing. This statement has been signed by numerous medical organizations, including the World Medical Association.
  30. Arnold, D.G., ed. (March 2011), The Ethics of Global Climate Change, Cambridge University Press, ISBN 9781107000698
  31. "Editorial: The Science of Climate Change". Science. 292 (5520): 1261. May 18, 2001. doi:10.1126/science.292.5520.1261.
  32. 1 2 The Science of Climate Change, The Royal Society
  33. Joint science academies’ statement: Global response to climate change, 2005
  34. 2007 Joint Science Academies' Statement
  35. 1 2 "Joint statement by the Network of African Science Academies (NASAC) to the G8 on sustainability, energy efficiency and climate change" (PDF). Network of African Science Academies. 2007. Retrieved 2012-08-28.
  36. 2008 Joint Science Academies’ Statement
  37. "Stanowisko Zgromadzenia Ogólnego PAN z dnia 13 grudnia 2007 r" (PDF) (in Polish). Polish Academy of Sciences. Retrieved 2009-06-16. Note: As of 16 June 2009, PAS has not issued this statement in English, all citations have been translated from Polish.
  38. 1 2 AAAS Board Statement on Climate Change December 2006
  39. FASTS Statement on Climate Change (PDF), 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."
  40. 1 2 Committee on the Science of Climate Change, Division on Earth and Life Studies, National Research Council (2001). Climate Change Science: An Analysis of Some Key Questions. Washington DC: National Academy Press. ISBN 0-309-07574-2.
  41. Wratt, David; Renwick, James (2008-07-10). "Climate change statement from the Royal Society of New Zealand". The Royal Society of New Zealand. Retrieved 2010-01-20.
  42. Gray, Louise (May 29, 2010). "Royal Society to publish guide on climate change to counter claims of 'exaggeration'". The Daily Telegraph. London.
  43. 1 2 "New guide to science of climate change". The Royal Society. Retrieved 9 June 2010.
  44. Harrabin, Roger (27 May 2010). "Society to review climate message". BBC News. Retrieved 9 June 2010.
  45. Gardner, Dan (8 June 2010). "Some excitable climate-change deniers just don't understand what science is". Montreal Gazette. Archived from the original on 11 June 2010. Retrieved 9 June 2010.
  46. "Joint statement by the Network of African Science Academies (NASAC) to the G8 on sustainability, energy efficiency and climate change". 2007. Retrieved 22 May 2015. 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.
  47. European Academy of Sciences and Arts Let's Be Honest
  48. European Science Foundation Position Paper Impacts of Climate Change on the European Marine and Coastal Environment — Ecosystems Approach, 2007, pp. 7–10 "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."
  49. Panel Urges Global Shift on Sources of Energy
  50. "InterAcademy Council". InterAcademy Council. Retrieved 2012-07-30.
  51. "InterAcademy Council". InterAcademy Council. Retrieved 2012-07-30.
  52. "InterAcademy Council". InterAcademy Council. Retrieved 2012-07-30.
  54. 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)."
  55. American Institute of Physics Statement supporting AGU statement on human-induced climate change, 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."
  56. American Physical Society Climate Change Policy Statement, 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.
  57. AIP science policy document. (PDF), 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 biodiversity will fundamentally change the ecology of Earth."
  58. EPS Position Paper Energy for the future: The Nuclear Option (PDF), 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."
  59. Ledley, Tamara S.; Sundquist, Eric T.; Schwartz, Stephen E.; Hall, Dorothy K.; Fellows, Jack D.; Killeen, Timothy L. (September 28, 1999). "Climate Change and Greenhouse Gases" (PDF). EOS. 80 (39): 453–454, 457–458. doi:10.1029/99EO00325. Retrieved 16 August 2016. There is no known geologic precedent for large increases of atmospheric C02 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.
  60. "AGU Position Statement: Human Impacts on Climate". Retrieved 2012-07-30.
  61. "Human-induced Climate Change Requires Urgent Action". Position Statement. American Geophysical Union. Retrieved 14 August 2013.
  62. ASA, CSSA, and SSSA Position Statement on Climate Change
  63. "EFG Website | Home". 2011-08-10. Retrieved 2012-07-30.
  64. EFG Carbon Capture and geological Storage
  67. "The Geological Society of America - Position Statement on Global Climate Change". Retrieved 2012-07-30.
  68. "Geological Society - Climate change: evidence from the geological record". Retrieved 2012-07-30.
  69. IUGG Resolution 6
  72. "AMS Information Statement on Climate Change". 2012-08-20. Retrieved 2012-08-27.
  73. "Statement". AMOS. Retrieved 2012-07-30.
  74. CFCAS Letter to PM, November 25, 2005
  75. Canadian Meteorological and Oceanographic Society Letter to Stephen Harper (Updated, 2007)
  77. WMO’s Statement at the Twelfth Session of the Conference of the Parties to the U.N. Framework Convention on Climate Change.
  78. AMQUA "Petroleum Geologists’ Award to Novelist Crichton Is Inappropriate"
  79. 1 2 INQUA Statement On Climate Change.
  80. 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 extreme weather events, changing disease transmission dynamics, emerging and re-emerging diseases, and alterations to habitat and ecological systems that are essential to 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."
  81. 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."
  82. Scientific societies warn Senate: climate change is real, Ars Technica, October 22, 2009
  83. Letter to US Senators (PDF), October 2009
  84. Global Environmental Change — Microbial Contributions, Microbial Solutions (PDF), American Society For Microbiology, May 2006 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 biosphere on which we depend. Outbreaks of a number of diseases, including Lyme disease, hantavirus infections, dengue fever, bubonic plague, and cholera, have been linked to climate change."
  85. Australian Coral Reef Society official letter (PDF), 2006, archived from the original (PDF) on 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, coral bleaching, global climate change, 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."
  86. 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."
  87. SAF Forest Management and Climate Change (PDF), 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."
  88. SAF Forest Offset Projects in a Carbon Trading System (PDF), 2008 "Forests play a significant role in offsetting CO2 emissions, the primary anthropogenic GHG."
  89. Wildlife Society Global Climate Change and Wildlife (PDF) "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 photosynthesizers (i.e., plants).”
  90. AAP Global Climate Change and Children's Health, 2007 "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."
  91. ACPM Policy Statement Abrupt Climate Change and Public Health Implications, 2006 "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."
  92. American Medical Association Policy Statement, 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."
  93. American Public Health Association Policy Statement ‘’Addressing the Urgent Threat of Global Climate Change to Public Health and the Environment’’, 2007 "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."
  94. AMA Climate Change and Human Health — 2004, 2004 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."
  95. AMA Climate Change and Human Health — 2004. Revised 2008., 2008 "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, heatwaves and fires and the indirect effects of longer-term changes, such as drought, changes to the 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 malaria, dengue fever, Ross River virus and food-borne infections such as 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."
  96. World Federation of Public Health Associations resolution "Global Climate Change" (PDF), 2001 "Noting the conclusions of the 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...."
  97. WHO Protecting health from climate change (PDF), 2008, p. 2, retrieved 2009-04-18
  98. Statement supporting AGU statement on human-induced climate change, American Astronomical Society, 2004 "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."
  99. ASA Statement on Climate Change, 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."
  100. Lapp, David. "What Is Climate Change". Canadian Council of Professional Engineers. Retrieved 18 August 2015.
  101. Policy Statement, Climate Change and Energy, 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."
  102. IAGLR Fact Sheet The Great Lakes at a Crossroads: Preparing for a Changing Climate (PDF), 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."
  103. IPENZ Informatory Note, Climate Change and the greenhouse effect (PDF), 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."
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  108. AIPG Climate Change Letters sent to U.S. Government Officials
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