List of scientists opposing the mainstream scientific assessment of global warming
||The neutrality of this article is disputed. (March 2014)|
This is a list of notable scientists who have made statements that conflict with the mainstream scientific understanding of global warming as summarized by the Intergovernmental Panel on Climate Change and endorsed by other scientific bodies.
Establishing the mainstream scientific assessment, climate scientists agree that the global average surface temperature has risen over the last century. The scientific consensus and scientific opinion on climate change were summarized in the 2001 Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). The main conclusions on global warming were as follows:
- The global average surface temperature has risen 0.6 ± 0.2 °C since the late 19th century, and 0.17 °C per decade in the last 30 years.
- "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities", in particular emissions of the greenhouse gases carbon dioxide and methane.
- If greenhouse gas emissions continue the warming will also continue, with temperatures projected to increase by 1.4 °C to 5.8 °C between 1990 and 2100.[A] Accompanying this temperature increase will be increases in some types of extreme weather and a projected sea level rise. The balance of impacts of global warming become significantly negative at larger values of warming.
These findings are recognized by the national science academies of all the major industrialized nations.
Interest in such scientists has been increased by attempts to compile lists of dissenting scientists, including a minority report to the US Senate by Marc Morano, another by Arthur B. Robinson, which is often known as the Oregon Petition, and another by the Heartland Institute, all three of which have been criticized on a number of grounds.
Listing criteria: The notable scientists listed in this article have made statements since the publication of the Third Assessment Report which disagree with one or more of these 3 main conclusions. Each scientist included in this list has published at least one peer-reviewed article in the broad field of natural sciences, although not necessarily in a field relevant to climatology. To be included on this list it is not enough for a scientist to be merely included on a petition, survey, or list. Instead, the scientist must make their own statement.
- 1 Peer review
- 2 Scientists questioning the accuracy of IPCC climate projections
- 3 Scientists arguing that global warming is primarily caused by natural processes
- 4 Scientists arguing that the cause of global warming is unknown
- 5 Scientists arguing that global warming will have few negative consequences
- 6 See also
- 7 Notes
- 8 References
- 9 Further reading
- 10 External links
As of August 2012[update], fewer than 10 of the statements in the references for this list are part of the peer-reviewed scientific literature. The rest are statements from other sources such as interviews, opinion pieces, online essays and presentations. Academic papers almost never reject the view that human impacts have contributed to climate change. In 2004, a review of published abstracts from 928 peer-reviewed papers addressing "global climate change" found that none of them disputed the IPCC's conclusion that "Earth's climate is being affected by human activities" and that "most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations" A 2013 survey of 3984 abstracts from peer-reviewed papers published between 1991 and 2011 that expressed an opinion on anthropogenic global warming found that 97.1% agreed that climate change is caused by human activity. (see also Scientific opinion on climate change and Surveys of scientists' views on climate change).
Scientists questioning the accuracy of IPCC climate projections
Scientists in this section have made comments that it is not possible to project global climate accurately enough to justify the ranges projected for temperature and sea-level rise over the next century. They may not conclude specifically that the current IPCC projections are either too high or too low, but that the projections are likely to be inaccurate due to inadequacies of current global climate modeling.
- Judith Curry, climatologist and chair of the school of Earth and Atmospheric Sciences at the Georgia Institute of Technology
- Freeman Dyson, professor emeritus of the School of Natural Sciences, Institute for Advanced Study; Fellow of the Royal Society 
- Richard Lindzen, Alfred P. Sloan emeritus professor of atmospheric science at the Massachusetts Institute of Technology and member of the National Academy of Sciences
- Nils-Axel Mörner, retired head of the Paleogeophysics and Geodynamics department at Stockholm University, former chairman of the INQUA Commission on Sea Level Changes and Coastal Evolution (1999–2003).
- Garth Paltridge, retired chief research scientist, CSIRO Division of Atmospheric Research and retired director of the Institute of the Antarctic Cooperative Research Centre, visiting fellow ANU
- Peter Stilbs, professor of physical chemistry at Royal Institute of Technology, Stockholm.
- Philip Stott, professor emeritus of biogeography at the University of London
- Hendrik Tennekes, retired director of research, Royal Netherlands Meteorological Institute 
- Fritz Vahrenholt, German politician and energy executive with a doctorate in chemistry
Scientists arguing that global warming is primarily caused by natural processes
Scientists in this section have made comments that the observed warming is more likely attributable to natural causes than to human activities. Their views on climate change are usually described in more detail in their biographical articles.
- Khabibullo Abdusamatov, mathematician and astronomer at Pulkovo Observatory of the Russian Academy of Sciences
- Sallie Baliunas, astronomer, Harvard-Smithsonian Center for Astrophysics
- Tim Ball, professor emeritus of geography at the University of Winnipeg
- Robert M. Carter, former head of the school of earth sciences at James Cook University
- Ian Clark, hydrogeologist, professor, Department of Earth Sciences, University of Ottawa
- Chris de Freitas, associate professor, School of Geography, Geology and Environmental Science, University of Auckland
- David Douglass, solid-state physicist, professor, Department of Physics and Astronomy, University of Rochester
- Don Easterbrook, emeritus professor of geology, Western Washington University
- William M. Gray, professor emeritus and head of the Tropical Meteorology Project, Department of Atmospheric Science, Colorado State University
- William Happer, physicist specializing in optics and spectroscopy, Princeton University
- Ole Humlum, professor of geology at the University of Oslo
- Wibjörn Karlén, professor emeritus of geography and geology at the University of Stockholm.
- William Kininmonth, meteorologist, former Australian delegate to World Meteorological Organization Commission for Climatology
- David Legates, associate professor of geography and director of the Center for Climatic Research, University of Delaware
- Anthony Lupo, professor of atmospheric science at the University of Missouri
- Tad Murty, oceanographer; adjunct professor, Departments of Civil Engineering and Earth Sciences, University of Ottawa
- Tim Patterson, paleoclimatologist and professor of geology at Carleton University in Canada.
- Ian Plimer, professor emeritus of Mining Geology, the University of Adelaide.
- Arthur B. Robinson, biochemist and former faculty member at the University of California, San Diego
- Murry Salby, former chair of climate at Macquarie University
- Nicola Scafetta, research scientist in the physics department at Duke University
- Tom Segalstad, head of the Geology Museum at the University of Oslo
- Fred Singer, professor emeritus of environmental sciences at the University of Virginia
- Willie Soon, astrophysicist, Harvard-Smithsonian Center for Astrophysics
- Roy Spencer, principal research scientist, University of Alabama in Huntsville
- Henrik Svensmark, Danish National Space Center
- George H. Taylor, former director of the Oregon Climate Service at Oregon State University
- Jan Veizer, environmental geochemist, professor emeritus from University of Ottawa
Scientists arguing that the cause of global warming is unknown
Scientists in this section have made comments that no principal cause can be ascribed to the observed rising temperatures, whether man-made or natural. Their views on climate change are usually described in more detail in their biographical articles.
- Syun-Ichi Akasofu, retired professor of geophysics and founding director of the International Arctic Research Center of the University of Alaska Fairbanks.
- Claude Allègre, politician; geochemist, emeritus professor at Institute of Geophysics (Paris).
- Robert Balling, a professor of geography at Arizona State University.
- John Christy, professor of atmospheric science and director of the Earth System Science Center at the University of Alabama in Huntsville, contributor to several IPCC reports.
- Petr Chylek, space and remote sensing sciences researcher, Los Alamos National Laboratory.
- David Deming, geology professor at the University of Oklahoma.
- Ivar Giaever, professor emeritus of physics at the Rensselaer Polytechnic Institute.
- Vincent R. Gray, New Zealander physical chemist with expertise in coal ashes
- Keith Idso, botanist, former adjunct professor of biology at Maricopa County Community College District and the vice president of the Center for the Study of Carbon Dioxide and Global Change
- Antonino Zichichi, emeritus professor of nuclear physics at the University of Bologna and president of the World Federation of Scientists.
Scientists arguing that global warming will have few negative consequences
Scientists in this section have made comments that projected rising temperatures will be of little impact or a net positive for human society and/or the Earth's environment. Their views on climate change are usually described in more detail in their biographical articles.
- Craig D. Idso, faculty researcher, Office of Climatology, Arizona State University and founder of the Center for the Study of Carbon Dioxide and Global Change 
- Sherwood Idso, former research physicist, USDA Water Conservation Laboratory, and adjunct professor, Arizona State University
- Patrick Michaels, senior fellow at the Cato Institute and retired research professor of environmental science at the University of Virginia
- Global warming controversy
- Global warming conspiracy theory
- Hockey stick controversy
- List of authors from the IPCC AR4 WGI report
- List of climate scientists
- Merchants of Doubt
- Oregon petition
- ^ In its 2007 assessment report, IPCC projected likely temperature rise for various hypothetical levels of future greenhouse gas emissions, known as "emissions scenarios". They reported that during the 21st century the global surface temperature is likely to rise a further 1.1 to 2.9 °C (2.0 to 5.2 °F) for the lowest emissions scenario used in the report, and 2.4 to 6.4 °C (4.3 to 11.5 °F) for the highest.
- Anderegg, William R L; James W. Prall, Jacob Harold, and Stephen H. Schneider (2010). "Expert credibility in climate change". Proc. Natl. Acad. Sci. USA 107 (27): 12107–9. Bibcode:2010PNAS..10712107A. doi:10.1073/pnas.1003187107. PMC 2901439. PMID 20566872.
- Doran, Peter T.; Maggie Kendall Zimmerman (January 20, 2009). "Examining the Scientific Consensus on Climate Change". EOS 90 (3): 22–23. Bibcode:2009EOSTr..90...22D. doi:10.1029/2009EO030002.
- Climate Change 2001: Working Group I: The Scientific Basis p.5 – IPCC
- Climate Change 2001: Working Group I: The Scientific Basis p.7 – IPCC
- Climate Change 2001: Working Group I: The Scientific Basis p.8 – IPCC
- Working Group II: Impacts, Adaptation and Vulnerability p.958 – IPCC
- "Joint Science Academies' Statement" (PDF). Retrieved August 9, 2010.
- Morano, Marc (11 December 2008). "U. S. Senate Minority Report: More Than 700 International Scientists Dissent Over Man-Made Global Warming Claims". Senate Committee on Environment and Public Works. Retrieved 1 September 2013.
- "Global Warming Petition Project". Retrieved 2 March 2014.
- 500 Scientists Whose Research Contradicts Man-Made Global Warming Scares, by Dennis T. Avery. From the Heartland Institute website; published September 14, 2007, accessed June 20, 2008.
- Kaufman, Leslie (April 9, 2009). "Dissenter on Warming Expands His Campaign". New York Times.
- McKnight, David (August 2, 2008). "The climate change smokescreen". Sydney Morning Herald. Retrieved December 28, 2009.
- Grandia, Kevin (22 July 2009). "The 30,000 Global Warming Petition Is Easily-Debunked Propaganda". Huffington Post. Retrieved 2 March 2014.
- Oreskes, Naomi (3 December 2004). "The Scientific Consensus on Climate Change". Science 306 (5702): 1686. doi:10.1126/science.1103618. PMID 15576594., internal citation omitted
- Cook, J.; Nuccitelli, D.; Green, S. A.; Richardson, M.; Winkler, B. R.; Painting, R.; Way, R.; Jacobs, P.; Skuce, A. (2013). "Quantifying the consensus on anthropogenic global warming in the scientific literature". Environmental Research Letters 8 (2): 024024. doi:10.1088/1748-9326/8/2/024024.
- Lemonick, Michael D. (1 November 2010). "Climate heretic: Judith Curry turns on her colleagues". Nature. Retrieved 15 February 2014. "Few scientists would claim the IPCC is perfect, but Curry thinks it needs thoroughgoing reform. She accuses it of "corruption." "I'm not going to just spout off and endorse the IPCC," she says, "because I think I don't have confidence in the process.""
- Freeman Dyson, in correspondence with editor Steve Connor (February 25, 2011), "Letters to a heretic: An email conversation with climate change sceptic Professor Freeman Dyson", The Independent, "First, the computer models are very good at solving the equations of fluid dynamics but very bad at describing the real world. [...] Sixth, summing up the other five reasons, the climate of the earth is an immensely complicated system and nobody is close to understanding it."
- "The Climate Science Isn't Settled", The Wall Street Journal online, November 30, 2009, "Claims that climate change is accelerating are bizarre. [...] The quality of the data is poor [...] The general support for warming is based not so much on the quality of the data, but rather on the fact that there was a little ice age from about the 15th to the 19th century."
- "What Catastrophe?", The Weekly Standard, January 13, 2014
- Zedillo, Ernesto, ed. (2008). Global Warming: Looking Beyond Kyoto. Brookings Institution Press. pp. 21–. ISBN 0-8157-9716-8.
- Nils-Axel Mörner (Mar 30, 2005), Economics of Climate Change: 12-ii Session 2005–06 Evidence to Select Committee on Economic Affairs II, The Stationery Office, p. 269, "In conclusion, observational data do not support the sea level rise scenario. On the contrary, they seriously contradict it."
- Paltridge, Garth (2009). the Climate Caper. Connor Court Publishing. ISBN 978-1-921421-25-9. "There are good and straightforward scientific reasons to believe that the burning of fossil fuel and consequent increase in atmospheric carbon dioxide will lead to an increase in the average temperature of the world above that which would otherwise be the case. Whether the increase will be large enough to be noticeable is still an unanswered question."
- Peter Stilbs and Åke Ortmark (12 January 2014, 2005), Expressen, gå inte på klimatbluffen, "IPCC gör ingen egen forskning, utan söker som grupp stöd för en given hypotes - att koldioxiden har en avgörande betydelse för jordens framtida klimat. Detta är egentligen ogörligt, då ingen ännu har klarlagt klimatsystemets naturliga variationer. Enligt de vetenskapliga principer som växt fram under hundratals år tyder de senaste 20 årens observationer snarare på att hypotesen är falsk. (Own translation to English: The IPCC does not make its own research, but is a group searching for a given hypothesis – that carbon dioxide is crucial for the earth’s future climate. This is actually impossible since nobody has yet clarifed the climate system’s natural variability. According to the scientific principles that have developed over hundreds of years, the last 20 years of observations rather indicate that the hypothesis is false.)"
- Global Warming Is Not A Crisis, "It is claimed, on the basis of computer models, that this should lead to 1.1 – 6.4 C warming. What is rarely noted is that we are already three-quarters of the way into this in terms of radiative forcing, but we have only witnessed a 0.6 (+/-0.2) C rise, and there is no reason to suppose that all of this is due to humans."
- Tennekes, Hendrik. "A Skeptical View of Climate Models". "The blind adherence to the harebrained idea that climate models can generate 'realistic' simulations of climate is the principal reason why I remain a climate skeptic."
- "Breaking Global Warming Taboos: 'I Feel Duped on Climate Change'". Spiegel Online. 8 February 2012. Retrieved 19 February 2014. "CO2 alone will never cause a warming of more than 2 degrees Celsius (3.6 degrees Fahrenheit) by the end of the century. Only with the help of supposed amplification effects, especially water vapor, do the computers arrive at a drastic temperature increase."
- Meehl, G.A.; W.M. Washington, C.A. Ammann, J.M. Arblaster, T.M.L. Wigleym and C. Tebaldi (2004). "Combinations of Natural and Anthropogenic Forcings in Twentieth-Century Climate". Journal of Climate 17: 3721–3727. Bibcode:2004JCli...17.3721M. doi:10.1175/1520-0442(2004)017<3721:CONAAF>2.0.CO;2.
- "Russian academic says CO2 not to blame for global warming". Russian International News Agency. 15 January 2007. Retrieved 24 August 2012. "Global warming results not from the emission of greenhouse gases [...], but from an unusually high level of solar radiation and [...] growth in its intensity."
- Baliunas, Sallie (August 2002). "Warming Up to the Truth". The Heritage Foundation. Retrieved 31 August 2012.
- Baliunas, Sallie; Willie Soon (22 August 2002). "Global Warming Science vs. Computer Model Speculation: Just Ask the Experts". Capitalism Magazine. Retrieved 31 August 2012. "[T]he recent warming trend in the surface temperature record cannot be caused by the increase of human-made greenhouse gases in the air."
- Coren, Michael (13 February 2010). "Climatology expert threatened for climate change views". Toronto Sun. Retrieved 6 March 2014. ""There has always been and always will be climate change, but it has very little to do with human activity and has nothing at all to do with pollution of course."
- McLean, J. D.; de Freitas, C. R.; Carter, R. M. (2009). "Influence of the Southern Oscillation on tropospheric temperature". Journal of Geophysical Research 114: D14104. Bibcode:2009JGRD..11414104M. doi:10.1029/2008JD011637.
- Ian Clark (March 22, 2004). "Letter to the editor of The Hill Times". Natural Resources Stewardship Project. Archived from the original on February 10, 2009. Retrieved August 26, 2011. "We know that [the sun] was responsible for climate change in the past, and so is clearly going to play the lead role in present and future climate change. And interestingly... solar activity has recently begun a downward cycle."
- Chris de Freitas (May 9, 2006). "Chris de Freitas: Evidence must prevail". The New Zealand Herald. Archived from the original on May 23, 2006. Retrieved August 26, 2011. "To support the argument that carbon dioxide is causing [global warming], the evidence would have to distinguish between human-caused and natural warming. This has not been done."
- Phillip V Brennan (December 10, 2007). "New Study Explodes Human-Global Warming Story". Newsmax.com. Archived from the original on May 11, 2008. Retrieved August 26, 2011. "[...]observed increases in carbon dioxide and other greenhouse gases make only a negligible contribution to climate warming."
- Easterbrook, Don (22–25 October 2006). "THE CAUSE OF GLOBAL WARMING AND PREDICTIONS FOR THE COMING CENTURY". Philadelphia Annual Meeting. Retrieved 31 August 2012. "Because the warming periods in these oscillations [of glaciers] occurred well before atmospheric CO2 began to rise rapidly in the 1940s, they could not have been caused by increased atmospheric CO2, and global warming since 1900 could well have happened without any effect of CO2. If the cycles continue as in the past, the current warm cycle should end soon[...]"
- Achenbach, Joel (28 May 2006). "The Tempest". The Washington Post (Washington DC: WPC). ISSN 0190-8286. Retrieved 1 September 2012. "I am of the opinion that [global warming] is one of the greatest hoaxes ever perpetrated on the American people."
- Raymond Brusca (January 12, 2009). "Professor denies global warming theory". "[Global warming] probably has little to do with carbon dioxide, just like past warmings had little to do with carbon dioxide"
- Halfdan Carstens (2013 (GEO O1)). "Klimatolog i hardt vær". Retrieved January 9, 2014. "[Based on my own observations of how the climate varies naturally, I am skeptical of the CO2 hypothesis (own translation from Norwegian)"
- Wibjörn Karlén (January 7, 2010). "Lilla istiden kan redan vara här". Retrieved January 16, 2014. "[After a long time of studying climate variations, I have come to the conclusion that the space weather suggests that we are more likely heading towards a colder period than a warmer. (own translation from Swedish)"
- William Kininmonth, Climate Change: A Natural Hazard, archived from the original on August 28, 2007, retrieved August 26, 2011, "Natural variability of the climate system has been underestimated by IPCC and has, to now, dominated human influences."
- Legates, David (May 2006). "Climate Science: Climate Change and Its Impacts". National Center for Policy Analysis. Retrieved 31 August 2012. "About half of the warming during the 20th century occurred prior to the 1940s, and natural variability accounts for all or nearly all of the warming."
- Silvey, Janese (5 March 2012). "Professor details role as climate consultant". Columbia Tribune. Retrieved 15 April 2014. "There's no doubt the climate is changing; that's a given," he said. "But the question is: What's causing it. Is it mankind alone, which a lot of people say? Is it some mix of man and nature? Or is it nature? I would say nature is mostly responsible. There may be a role for man in there somewhere, but how much, I don't know."
- Robinson, Cindy (Spring 2005). "Global warning? Controversy heats up in the scientific community". Carleton University Magazine. Retrieved 31 August 2012. "There is no global warming due to human anthropogenic activities."
- Tom, Harris (June 12, 2006). "Global warming, Scientists, Al Gore climate change". Canada Free Press. Retrieved 31 August 2012. "There is no meaningful correlation between CO2 levels and Earth's temperature over this [geologic] time frame."
- Patterson, Timothy (June 2007). "Read the Sunspots". Financial Post.
- "Wild weather ignites climate change debate". Australian Broadcasting Company - Lateline. Aug 2002 (US). Retrieved 31 August 2012. "Natural climate changes occur unrelated to carbon dioxide contents."
- Robinson, Arthur B. (1997). "Science Has Spoken: Global Warming is a Myth". Dow Jones & Company. Retrieved 18 February 2014. "we needn't worry about human use of hydrocarbons warming the Earth. We also needn't worry about environmental calamities, even if the current, natural warming trend continues: After all the Earth has been much warmer during the past 3,000 years without ill effects."
- Bolt, Andrew (3 August 2011). "New research: warmth produces these carbon dioxide concentrations". Herald Sun. Retrieved 2 April 2014. "Salby...suggests that its warmth which tends to produce more CO2, rather than vice versa - which, incidentally is the story of the past recoveries from ice ages."
- "I cambi climatici e le loro cause, una discussione su alcuni punti chiave (Climate Change and Its Causes, A Discussion About Some Key Issues)". La Chimica e l'Industria. 2010. pp. 70–75. Retrieved 31 August 2012. "At least 60% of the warming of the Earth observed since 1970 appears to be induced by natural cycles which are present in the solar system. A climatic stabilization or cooling until 2030–2040 is forecast by the phenomenological model."
- "Scafetta webpage".
- Segalstad, Tom. "What is CO2 – friend or foe?". Retrieved July 4, 2009. "The IPCC's temperature curve (the so-called 'hockey stick' curve) must be in error [...] All measurements of solar luminosity and 14C isotopes show that there is at present an increasing solar radiation which gives a warmer climate"
- Singer, S. Fred (April 22, 2005). "'Flat Earth Award' nominee's challenge to Chicken Littles". Christian Science Monitor. "The greenhouse effect is real. However, the effect is minute, insignificant, and very difficult to detect."
- "The Denial Machine (ABC Interview)". 2008.
- "Climate of Doubt". PBS Frontline. October 23, 2012.
- William J Cromie (April 24, 2003). "Global warming is not so hot: 1003 was worse, researchers find". Harvard University Gazette. Retrieved August 26, 2011. "there's increasingly strong evidence that previous research conclusions [...] may have been biased by underestimation of natural climate variations."
- "Testimony of Roy W. Spencer". before the Senate Environment and Public Works Committee. 22 July 2008. Retrieved 31 August 2012. "I predict that [scientists will realise] most of the climate change we have observed is natural, and that mankind’s role is relatively minor"
- Svensmark, Henrik (2007). "Cosmoclimatology: a new theory emerges" (PDF). Astronomy & Geophysics 48 (1): 18–24. Retrieved December 19, 2011. "The case for anthropogenic climate change during the 20th century rests primarily on the fact that concentrations of carbon dioxide and other greenhouse gases increased and so did global temperatures. Attempts to show that certain details in the climatic record confirm the greenhouse forcing (e.g. Mitchell et al. 2001) have been less than conclusive. By contrast, the hypothesis that changes in cloudiness obedient to cosmic rays help to force climate change predicts a distinctive signal that is in fact very easily observed, as an exception that proves the rule."
- Tomlinson, Stuart (21 February 2008). "Update: Controversial "State Climatologist" Steps Aside". OregonLive.com. Retrieved 20 March 2014. "Taylor said he believes climate change is a combination of natural factor and human factors. "I don't deny that human activities affect climate change," he said. "But I believe up to now, natural variations have played a more important role than human activities."
- "Celestial Climate Driver: A Perspective from Four Billion Years of the Carbon Cycle". Geoscience Canada. 1 32. 2005. Retrieved 26 August 2012. "At this stage, two scenarios of potential human impact on climate appear feasible: (1) the standard IPCC model that advocates the leading role of greenhouse gases, particularly of CO2, and (2) the alternative model that argues for celestial phenomena as the principal climate driver. The two scenarios are likely not even mutually exclusive, but a prioritization may result in different relative impact. Models and empirical observations are both indispensable tools of science, yet when discrepancies arise, observations should carry greater weight than theory. If so, the multitude of empirical observations favours celestial phenomena as the most important driver of terrestrial climate on most time scales, but time will be the final judge."
- Syun-Ichi, Akasofu (June 15, 2007). "On the Fundamental Defect in the IPCC’s Approach to Global Warming Research by Syun-Ichi Akasofu". Climate Science: Roger Pielke Sr. wordpress.com. Retrieved 31 August 2012. "[T]he method of study adopted by the International Panel of Climate Change (IPCC) is fundamentally flawed, resulting in a baseless conclusion: Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. Contrary to this statement ..., there is so far no definitive evidence that 'most' of the present warming is due to the greenhouse effect. ... [The IPCC] should have recognized that the range of observed natural changes should not be ignored, and thus their conclusion should be very tentative. The term 'most' in their conclusion is baseless."
- "Climat: la prévention, oui, la peur, non" (in French). L'Express. May 10, 2006. Archived from the original on November 17, 2006. Retrieved August 26, 2011. ":The increase in the CO2 content of the atmosphere is an observed fact and mankind is most certainly responsible. In the long term, this increase will without doubt become harmful, but its exact role in the climate is less clear. Various parameters appear more important than CO2. Consider the water cycle and formation of various types of clouds, and the complex effects of industrial or agricultural dust. Or fluctuations of the intensity of the solar radiation on annual and century scale, which seem better correlated with heating effects than the variations of CO2 content."
- Balling, Robert (September 2003). The Increase in Global Temperature: What it Does and Does Not Tell Us. George C. Marshall Institute. "[I]t is very likely that the recent upward trend [in global surface temperature] is very real and that the upward signal is greater than any noise introduced from uncertainties in the record. However, the general error is most likely to be in the warming direction, with a maximum possible (though unlikely) value of 0.3 °C. ... At this moment in time we know only that: (1) Global surface temperatures have risen in recent decades. (2) Mid-tropospheric temperatures have warmed little over the same period. (3) This difference is not consistent with predictions from numerical climate models."
- Christy, John R.; Douglass, David H. (2009). "Limits on CO2 Climate Forcing from Recent Temperature Data of Earth" (PDF). Energy & Environment 20: 177–189. Retrieved June 17, 2011. "...the data show a small underlying positive trend that is consistent with CO2 climate forcing with no-feedback. [...] There is disagreement in regard to the validity of the global warming hypothesis that states that there are positive feedback processes leading to gains g that are larger than 1, perhaps as large as 3 or 4. However, recent studies suggest that the values of g is much smaller."
- Christy, John (November 1, 2007). "My Nobel Moment". Wall Street Journal. Retrieved November 2, 2007. "...I see neither the developing catastrophe nor the smoking gun proving that human activity is to blame for most of the warming we see. Rather, I see a reliance on climate models (useful but never "proof") and the coincidence that changes in carbon dioxide and global temperatures have loose similarity over time."
- Petr Chylek (April 2002). "A Long Term Perspective on Climate Change". Heartland.org. Archived from the original on September 29, 2007. Retrieved August 26, 2011. "Carbon dioxide should not be considered as a dominant force behind the current warming...how much of the [temperature] increase can be ascribed to CO2, to changes in solar activity, or to the natural variability of climate is uncertain"
- Dr. David Deming (12 06 2006). "U.S. Senate Committee on Environment & Public Works, Hearing Statements". epw.senate.gov. Retrieved 31 August 2012. "The amount of climatic warming that has taken place in the past 150 years is poorly constrained, and its cause – human or natural – is unknown. There is no sound scientific basis for predicting future climate change with any degree of certainty. If the climate does warm, it is likely to be beneficial to humanity rather than harmful. In my opinion, it would be foolish to establish national energy policy on the basis of misinformation and irrational hysteria."
- Ivar Giaever (26 June 2011). "De forunderlige klimamytene". Retrieved 17 June 2013. "Therefore, it certainly is not likely that the temperature rise is due to CO2, because the correlation is weak."
- Gray, Vincent R. (April 2008). "The Global Warming Scam". Retrieved 13 February 2014.
- Idso, Craig D., Idso, Keith E. (1998). "Carbon Dioxide and Global Warming". CO2science.org. Archived from the original on February 24, 2007. Retrieved 16 March 2014. "...there is no compelling reason to believe that the rise in temperature was caused by the rise in CO2. Furthermore, it is highly unlikely that future increases in the air's CO2 content will produce any global warming; for there are numerous problems with the popular hypothesis that links the two phenomena."
- "ZENIT - Global Warming Natural, Says Expert". zenit.org. 2007-04-27. Retrieved August 31, 2012. "it is not possible to exclude the idea that climate changes can be due to natural causes"
- Craig Idso. "A Science- Based Rebuttal to the Testimony of Al Gore before the United States Senate Environment & Public Works Committee". Center for the Study of Carbon Dioxide and Global Change. Retrieved 26 August 2012. "The rising CO2 content of the air should boost global plant productivity dramatically, enabling humanity to increase food, fiber and timber production and thereby continue to feed, clothe, and provide shelter for their still-increasing numbers ... this atmospheric CO2-derived blessing is as sure as death and taxes."
- Sherwood B. Idso, Craig D. Idso and Keith E. Idso (November 2003). "Enhanced or Impaired? Human Health in a CO2-Enriched Warmer World". Center for the Study of Carbon Dioxide and Global Change. p. 30. Retrieved 26 August 2012. "[W]arming has been shown to positively impact human health, while atmospheric CO2 enrichment has been shown to enhance the health-promoting properties of the food we eat, as well as stimulate the production of more of it. ... [W]e have nothing to fear from increasing concentrations of atmospheric CO2 and global warming."
- Michaels, Patrick (October 16, 2003). "Posturing and Reality on Warming". CATO Institute. Retrieved June 10, 2009. "Scientists know quite precisely how much the planet will warm in the foreseeable future, a modest three-quarters of a degree (Celsius), plus or minus a mere quarter-degree ... a modest warming is a likely benefit... human warming will be strongest and most obvious in very cold and dry air, such as in Siberia and northwestern North America in the dead of winter."
- WG1. "Chap 10, Executive Summary". IPCC.
- Boykoff, Maxwell (2009), "Ch. 39: Carbonundrums: The Role of the Media: Contemporary Media Courtesans: Climate Contrarians", in Schneider, Stephen H.; Rosencranz, Armin; Mastrandrea, Michael D. et al., Climate change science and policy, Island Press, p. 401, ISBN 978-1-59726-567-6
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