This is a list of notable scientists who have made statements...

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:

1. 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.[3]
2. "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.[4]
3. 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.[5] The balance of impacts of global warming become significantly negative at larger values of warming.[6]

These findings are recognized by the national science academies of all the major industrialized nations.[7]
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.
Peer review
As of August 2012, 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"[8] 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.[9] (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.

• Freeman Dyson, professor emeritus of the School of Natural Sciences, Institute for Advanced Study; Fellow of the Royal Society [10]
• Richard Lindzen, Alfred P. Sloan professor of atmospheric science at the Massachusetts Institute of Technology and member of the National Academy of Sciences[11][12][13]

• 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).[14]
• 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[15]
• Peter Stilbs, professor of physical chemistry at Royal Institute of Technology, Stockholm. [16]
• Philip Stott, professor emeritus of biogeography at the University of London[17]
• Hendrik Tennekes, retired director of research, Royal Netherlands Meteorological Institute [18]

Scientists arguing that global warming is primarily caused by natural processes


Graph showing the ability with which a global climate model is able to reconstruct the historical temperature record, and the degree to which those temperature changes can be decomposed into various forcing factors. It shows the effects of five forcing factors: greenhouse gases, man-made sulfate emissions, solar variability, ozone changes, and volcanic emissions.[19]
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[20]
• Sallie Baliunas, astronomer, Harvard-Smithsonian Center for Astrophysics[21][22]
• Ian Clark, hydrogeologist, professor, Department of Earth Sciences, University of Ottawa[23]
• Chris de Freitas, associate professor, School of Geography, Geology and Environmental Science, University of Auckland[24]
• David Douglass, solid-state physicist, professor, Department of Physics and Astronomy, University of Rochester[25]
• Don Easterbrook, emeritus professor of geology, Western Washington University[26]
• William M. Gray, professor emeritus and head of the Tropical Meteorology Project, Department of Atmospheric Science, Colorado State University[27]
• William Happer, physicist specializing in optics and spectroscopy, Princeton University[28]
• Ole Humlum, professor of geology at the University of Oslo[29]
• Wibjörn Karlén, professor emeritus of geography and geology at the University of Stockholm.[30]
• William Kininmonth, meteorologist, former Australian delegate to World Meteorological Organization Commission for Climatology[31]
• David Legates, associate professor of geography and director of the Center for Climatic Research, University of Delaware[32]
• Tad Murty, oceanographer; adjunct professor, Departments of Civil Engineering and Earth Sciences, University of Ottawa[33]
• Tim Patterson, paleoclimatologist and professor of geology at Carleton University in Canada.[34][35]
• Ian Plimer, professor emeritus of Mining Geology, the University of Adelaide.[36]
• Nicola Scafetta, research scientist in the physics department at Duke University[37][38]
• Tom Segalstad, head of the Geology Museum at the University of Oslo[39]
• Fred Singer, professor emeritus of environmental sciences at the University of Virginia[40][41][42]
• Willie Soon, astrophysicist, Harvard-Smithsonian Center for Astrophysics[43]
• Roy Spencer, principal research scientist, University of Alabama in Huntsville[44]
• Henrik Svensmark, Danish National Space Center[45]
• Jan Veizer, environmental geochemist, professor emeritus from University of Ottawa[46]

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.[47]
• Claude Allègre, politician; geochemist, emeritus professor at Institute of Geophysics (Paris).[48]
• Robert C. Balling, Jr., a professor of geography at Arizona State University.[49]
• 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.[50][51]
• Petr Chylek, space and remote sensing sciences researcher, Los Alamos National Laboratory.[52]
• David Deming, geology professor at the University of Oklahoma.[53]
• Ivar Giaever, professor emeritus at the Rensselaer Polytechnic Institute.[54]

Antonino Zichichi, emeritus professor of nuclear physics at the University of Bologna and president of the World Federation of Scientists.[55]

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 [56]
• Sherwood Idso, former research physicist, USDA Water Conservation Laboratory, and adjunct professor, Arizona State University[57]
• Patrick Michaels, senior fellow at the Cato Institute and retired research professor of environmental science at the University of Virginia[58]