List of scientists opposing the mainstream scientific assessment of global warming

This is a list of scientists who have made statements that conflict with the mainstream scientific understanding of global warming as summarized by the Intergovernmental Panel on Climate Change

Intergovernmental Panel on Climate Change

The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...

and endorsed by other scientific bodies.

Climate scientists agree that the global average surface temperature has risen over the last century. The scientific consensus

Scientific consensus

Scientific consensus is the collective judgment, position, and opinion of the community of scientists in a particular field of study. Consensus implies general agreement, though not necessarily unanimity. Scientific consensus is not by itself a scientific argument, and it is not part of the...

and scientific opinion on climate change

Scientific opinion on climate change

The predominant scientific opinion on climate change is that the Earth is in an ongoing phase of global warming primarily caused by an enhanced greenhouse effect due to the anthropogenic release of carbon dioxide and other greenhouse gases...

were summarized in the 2001 Third Assessment Report

IPCC Third Assessment Report

The IPCC Third Assessment Report, Climate Change 2001, is an assessment of available scientific and socio-economic information on climate change by the IPCC. The IPCC was established in 1988 by the United Nations Environment Programme and the UN's World Meteorological Organization ".....

of the Intergovernmental Panel on Climate Change (IPCC). The main conclusions on global warming

Global warming

Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

were as follows:

The global average surface temperature
Instrumental temperature record
The instrumental temperature record shows fluctuations of the temperature of the global land surface and oceans. This data is collected from several thousand meteorological stations, Antarctic research stations and satellite observations of sea-surface temperature. Currently, the longest-running...

has risen 0.6 ± 0.2 °C
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...

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
Attribution of recent climate change
Attribution of recent climate change is the effort to scientifically ascertain mechanisms responsible for recent changes observed in the Earth's climate...

", in particular emissions of the greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

es 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. Accompanying this temperature increase will be increases in some types of extreme weather and a projected sea level rise. On balance the impacts of global warming will be significantly negative, especially for larger values of warming.

The listed notable scientists have made statements since the publication of the Third Assessment Report which disagree with one or more of the principal conclusions of the IPCC. Each scientist has published at least one peer-reviewed article in the natural sciences. The article need not have been written in recent years nor be in a field relevant to climate. She or he has made an attributable statement of disagreement in some forum (and is not merely included on a petition, survey, or list).

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. Their views on climate change are usually described in more detail in their biographical articles.

Freeman Dyson, Professor Emeritus of the School of Natural Sciences, Institute for Advanced Study
Institute for Advanced Study
The Institute for Advanced Study, located in Princeton, New Jersey, United States, is an independent postgraduate center for theoretical research and intellectual inquiry. It was founded in 1930 by Abraham Flexner...

; Fellow of the Royal Society: "First, the computer models are very good at solving the equations of fluid dynamics but very bad at describing the real world. The real world is full of things like clouds and vegetation and soil and dust which the models describe very poorly. Second, we do not know whether the recent changes in climate are on balance doing more harm than good. The strongest warming is in cold places like Greenland. More people die from cold in winter than die from heat in summer. Third, there are many other causes of climate change besides human activities, as we know from studying the past. Fourth, the carbon dioxide in the atmosphere is strongly coupled with other carbon reservoirs in the biosphere, vegetation and top-soil, which are as large or larger. It is misleading to consider only the atmosphere and ocean, as the climate models do, and ignore the other reservoirs. Fifth, the biological effects of CO2 in the atmosphere are beneficial, both to food crops and to natural vegetation. The biological effects are better known and probably more important than the climatic effects. Sixth, summing up the other five reasons, the climate of the earth is an immensely complicated system and nobody is close to understanding it."

Richard Lindzen, Alfred P. Sloan Professor of Atmospheric Science at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

and member of the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...

:"We are quite confident (1) that global mean temperature is about 0.5 °C higher than it was a century ago; (2) that atmospheric levels of CO₂ have risen over the past two centuries; and (3) that CO₂ is a greenhouse gas whose increase is likely to warm the earth (one of many, the most important being water vapor and clouds). But – and I cannot stress this enough – we are not in a position to confidently attribute past climate change to CO₂ or to forecast what the climate will be in the future.". "[T]here has been no question whatsoever that CO₂ is an infrared absorber (i.e., a greenhouse gas – albeit a minor one), and its increase should theoretically contribute to warming. Indeed, if all else were kept equal, the increase in CO₂ should have led to somewhat more warming than has been observed."

Nils-Axel Mörner
Nils-Axel Mörner
Nils-Axel Mörner, born 1938, is the former head of the Paleogeophysics and Geodynamics department at Stockholm University. He retired in 2005. He was president of the International Union for Quaternary Research Commission on Neotectonics...

, retired head of the Paleogeophysics and Geodynamics department at Stockholm University
Stockholm University
Stockholm University is a state university in Stockholm, Sweden. It has over 28,000 students at four faculties, making it one of the largest universities in Scandinavia. The institution is also frequently regarded as one of the top 100 universities in the world...

and former Chairman of the INQUA Commission on Sea Level Changes and Coastal Evolution (1999-2003): "In conclusion, observational data do not support the sea level rise scenario. On the contrary, they seriously contradict it. Therefore we should free the world from the condemnation of becoming extensively flooded in the near future."

Garth Paltridge
Garth Paltridge
Garth William Paltridge, , is a retired Australian atmospheric physicist. He is presently a Visiting Fellow at the Australian National University and Emeritus Professor and Honorary Research Fellow at the Institute of Antarctic and Southern Oceans Studies , University of Tasmania.-Career:Paltridge...

, Visiting Fellow ANU and retired Chief Research Scientist, CSIRO Division of Atmospheric Research and retired Director of the Institute of the Antarctic Cooperative Research Centre: "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."

Philip Stott
Philip Stott
Philip Stott is a professor emeritus of biogeography at the School of Oriental and African Studies, University of London, and a former editor of the Journal of Biogeography .-Background:...

, professor emeritus of biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...

at the University of London
University of London
-20th century:Shortly after 6 Burlington Gardens was vacated, the University went through a period of rapid expansion. Bedford College, Royal Holloway and the London School of Economics all joined in 1900, Regent's Park College, which had affiliated in 1841 became an official divinity school of the...

: "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."

Hendrik Tennekes
Hendrik Tennekes
Hendrik Tennekes was the director of research at the Royal Dutch Meteorological Institute , and was a Professor of Aeronautical Engineering at Pennsylvania State University. He is known for his work in the fields of turbulence and multi-modal forecasting...

, retired Director of Research, Royal Netherlands Meteorological Institute: "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."

Antonino Zichichi
Antonino Zichichi
Antonino Zichichi is an Italian physicist who has worked in the field of nuclear physics.-Biography:Zichichi was born in Trapani, Sicily, in 1929. He has collaborated to several important discoveries in the field of subnuclear physics and has worked in some of the most important research...

, emeritus professor of nuclear physics
Nuclear physics
Nuclear physics is the field of physics that studies the building blocks and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those...

at the University of Bologna
University of Bologna
The Alma Mater Studiorum - University of Bologna is the oldest continually operating university in the world, the word 'universitas' being first used by this institution at its foundation. The true date of its founding is uncertain, but believed by most accounts to have been 1088...

and president of the World Federation of Scientists:"Models used by the Intergovernmental Panel on Climate Change (IPCC) are incoherent and invalid from a scientific point of view".

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
Khabibullo Abdusamatov
Habibullo Ismailovich Abdussamatov is a Russian astrophysicist of Uzbek descent. He is the supervisor of the Astrometria project of the Russian section of the International Space Station and the head of Space research laboratory at the Saint Petersburg-based Pulkovo Observatory of the Russian...

, mathematician
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

and astronomer
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

at Pulkovo Observatory
Pulkovo Observatory
The Pulkovo Astronomical Observatory астрономи́ческая обсервато́рия Росси́йской акаде́мии нау́к), the principal astronomical observatory of the Russian Academy of Sciences, located 19 km south of Saint Petersburg on Pulkovo Heights...

of the Russian Academy of Sciences
Russian Academy of Sciences
The Russian Academy of Sciences consists of the national academy of Russia and a network of scientific research institutes from across the Russian Federation as well as auxiliary scientific and social units like libraries, publishers and hospitals....

:"Global warming results not from the emission of greenhouse gases into the atmosphere, but from an unusually high level of solar radiation and a lengthy – almost throughout the last century – growth in its intensity."
Sallie Baliunas, astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

, Harvard-Smithsonian Center for Astrophysics
Harvard-Smithsonian Center for Astrophysics
The Harvard–Smithsonian Center for Astrophysics is one of the largest and most diverse astrophysical institutions in the world, where scientists carry out a broad program of research in astronomy, astrophysics, earth and space sciences, and science education...

:"Most of the increase in the air's concentration of greenhouse gases from human activities--over 80 percent--occurred after the 1940s. That means that the strong early 20th century warming must be largely, if not entirely, natural.""The coincident changes in the sun's changing energy output and temperature records on earth tend to argue that the sun has driven a major portion of the 20th century temperature change." "[T]he recent warming trend in the surface temperature record cannot be caused by the increase of human-made greenhouse gases in the air."

Ian Clark, hydrogeologist
Hydrogeology
Hydrogeology is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust, . The term geohydrology is often used interchangeably...

, professor, Department of Earth Sciences, University of Ottawa
University of Ottawa
The University of Ottawa is a bilingual, research-intensive, non-denominational, international university in Ottawa, Ontario. It is one of the oldest universities in Canada. It was originally established as the College of Bytown in 1848 by the Missionary Oblates of Mary Immaculate...

:"That portion of the scientific community that attributes climate warming to CO₂ relies on the hypothesis that increasing CO₂, which is in fact a minor greenhouse gas, triggers a much larger water vapour response to warm the atmosphere. This mechanism has never been tested scientifically beyond the mathematical models that predict extensive warming, and are confounded by the complexity of cloud formation – which has a cooling effect. ... 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
Chris de Freitas
Chris de Freitas is an Associate Professor in the School of Environment at the University of Auckland in New Zealand.-Education and professional career:...

, Associate Professor, School of Geography, Geology and Environmental Science, University of Auckland
University of Auckland
The University of Auckland is a university located in Auckland, New Zealand. It is the largest university in the country and the highest ranked in the 2011 QS World University Rankings, having been ranked worldwide...

:"There is evidence of global warming. ... But warming does not confirm that carbon dioxide is causing it. Climate is always warming or cooling. There are natural variability theories of warming. To support the argument that carbon dioxide is causing it, the evidence would have to distinguish between human-caused and natural warming. This has not been done."

David Douglass
David Douglass
David H. Douglass is an American physicist at the University of Rochester. Prof. Douglass received his B.S. in Physics from the University of Maine and his Ph.D. in Physics from the Massachusetts Institute of Technology. After positions at MIT Lincoln Laboratories and MIT, he was appointed...

, solid-state physicist
Solid-state physics
Solid-state physics is the study of rigid matter, or solids, through methods such as quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the large-scale properties of solid materials result from...

, professor, Department of Physics and Astronomy, University of Rochester
University of Rochester
The University of Rochester is a private, nonsectarian, research university in Rochester, New York, United States. The university grants undergraduate and graduate degrees, including doctoral and professional degrees. The university has six schools and various interdisciplinary programs.The...

:"The observed pattern of warming, comparing surface and atmospheric temperature trends, does not show the characteristic fingerprint associated with greenhouse warming. The inescapable conclusion is that the human contribution is not significant and that observed increases in carbon dioxide and other greenhouse gases make only a negligible contribution to climate warming."

Don Easterbrook
Don Easterbrook
Don J. Easterbrook is a geology professor emeritus at Western Washington University. From that perspective, he is skeptical of global warming. He has criticized Al Gore's film An Inconvenient Truth and IPCC temperature projections and has appeared on the Headline News program Glenn Beck and in the...

, emeritus professor of geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

, Western Washington University
Western Washington University
Western Washington University is one of six state-funded, four-year universities of higher education in the U.S. state of Washington. It is located in Bellingham and offers bachelor's and master's degrees.-History:...

:"Glaciers advanced from about 1890–1920, retreated rapidly from ~1925 to ~1945, readvanced from ~1945 to ~1977, and have been retreating since the present warm cycle began in 1977. ... Because the warming periods in these oscillations 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 and global temperatures should cool slightly until about 2035, then warm about 0.5°C from ~2035 to ~2065, and cool slightly until 2100."

William M. Gray
William M. Gray
William M. "Bill" Gray is Emeritus Professor of Atmospheric Science at Colorado State University , and head of the Tropical Meteorology Project at CSU's Department of Atmospheric Sciences. He is a pioneer in the science of forecasting hurricanes and one of the world's leading experts on tropical...

, Professor Emeritus and head of The Tropical Meteorology Project, Department of Atmospheric Science, Colorado State University
Colorado State University
Colorado State University is a public research university located in Fort Collins, Colorado. The university is the state's land grant university, and the flagship university of the Colorado State University System.The enrollment is approximately 29,932 students, including resident and...

:"This small warming is likely a result of the natural alterations in global ocean currents which are driven by ocean salinity variations. Ocean circulation variations are as yet little understood. Human kind has little or nothing to do with the recent temperature changes. We are not that influential." "I am of the opinion that [global warming] is one of the greatest hoaxes ever perpetrated on the American people."

William Happer
William Happer
William Happer is a physicist who has specialised in the study of optics and spectroscopy. He is the Cyrus Fogg Brackett Professor of Physics at Princeton University.-Education:...

, physicist specializing in optics
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...

and spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...

, Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....

:"All the evidence I see is that the current warming of the climate is just like past warmings. In fact, it's not as much as past warmings yet, and it probably has little to do with carbon dioxide, just like past warmings had little to do with carbon dioxide"

William Kininmonth
William Kininmonth (meteorologist)
William Robert Kininmonth is a retired Australian meteorologist noted for his views as an opponent of anthropogenic global warming theory and for his frequent writings on the topic of climate change.-Education:...

, meteorologist, former Australian delegate to World Meteorological Organization Commission for Climatology:"There has been a real climate change over the late nineteenth and twentieth centuries that can be attributed to natural phenomena. Natural variability of the climate system has been underestimated by IPCC and has, to now, dominated human influences."

David Legates
David Legates
David Russell Legates is a Professor of Geography at the University of Delaware. He is the former Director of the Center for Climatic Research at the same university, and a former Delaware State Climatologist....

, associate professor of geography
Geography
Geography is the science that studies the lands, features, inhabitants, and phenomena of Earth. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...

and director of the Center for Climatic Research, University of Delaware:"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."

Tad Murty
Tad Murty
Tad S. Murty is an Indian-Canadian oceanographer and expert on tsunamis. He is the former president of the Tsunami Society. He is an adjunct professor in the departments of Civil Engineering and Earth Sciences at the University of Ottawa...

, oceanographer; adjunct professor, Departments of Civil Engineering and Earth Sciences, University of Ottawa
University of Ottawa
The University of Ottawa is a bilingual, research-intensive, non-denominational, international university in Ottawa, Ontario. It is one of the oldest universities in Canada. It was originally established as the College of Bytown in 1848 by the Missionary Oblates of Mary Immaculate...

:[Global warming] "is the biggest scientific hoax being perpetrated on humanity. There is no global warming due to human anthropogenic activities. The atmosphere hasn’t changed much in 280 million years, and there have always been cycles of warming and cooling. The Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

period was the warmest on earth. You could have grown tomatoes at the North Pole"

Tim Patterson
Tim Patterson
R. Timothy Patterson is a professor of geology at Carleton University, where he is Director of the Ottawa-Carleton Geoscience Centre in Ottawa, Ontario, Canada. He is also a Senior Visiting Fellow in the School of Geography, Queen's University of Belfast, Northern Ireland. He holds a B.Sc. in...

, paleoclimatologist and Professor of Geology at Carleton University
Carleton University
Carleton University is a comprehensive university located in the capital of Canada, Ottawa, Ontario. The enabling legislation is The Carleton University Act, 1952, S.O. 1952. Founded as a small college in 1942, Carleton now offers over 65 programs in a diverse range of disciplines. Carleton has...

in Canada:"There is no meaningful correlation between CO₂ levels and Earth's temperature over this [geologic] time frame. In fact, when CO₂ levels were over ten times higher than they are now, about 450 million years ago, the planet was in the depths of the absolute coldest period in the last half billion years. On the basis of this evidence, how could anyone still believe that the recent relatively small increase in CO₂ levels would be the major cause of the past century's modest warming?"

Ian Plimer
Ian Plimer
Ian Rutherford Plimer is an Australian geologist, academic, professor of mining geology at the University of Adelaide, and a director of four mining companies...

, Professor emeritus of Mining Geology, The University of Adelaide: "Natural climate changes occur unrelated to carbon dioxide contents. We've had many, many times in the recent past where we've rapidly gone into a greenhouse and the carbon dioxide content has been far, far lower than the current carbon dioxide content... It looks as if carbon dioxide actually follows climate change rather than drives it".

Tom Segalstad
Tom Segalstad
Tom V. Segalstad is a Norwegian geologist. He has taught geochemistry, mineralogy, petrology, volcanology, structural geology, ore geology, and geophysics at the University of Oslo, Norway, and at Pennsylvania State University, United States....

, head of the Geology Museum at the University of Oslo
University of Oslo
The University of Oslo , formerly The Royal Frederick University , is the oldest and largest university in Norway, situated in the Norwegian capital of Oslo. The university was founded in 1811 and was modelled after the recently established University of Berlin...

:"The IPCC's temperature curve (the so-called 'hockey stick' curve) must be in error, because the Medieval warm period (the "Climate Optimum") and the Little Ice Age both are absent from their curve, on which the IPCC bases its future projections and recommended mitigation. All measurements of solar luminosity and 14C isotopes show that there is at present an increasing solar radiation which gives a warmer climate (Willson, R.C & Hudson, H.S. 1991: The Sun's luminosity over a complete solar cycle. Nature 351, 42-44; and Coffey, H.E., Erwin, E.H. & Hanchett, C.D.: Solar databases for global change models. www.ngdc.noaa.gov/stp/SOLAR/solarda3.html). Warmer climate was previously perceived as an optimum climate and not catastrophic. ... On a wet basis the Earth's atmosphere consists by mass of ~73.5% nitrogen, ~22.5% oxygen, ~2.7% water, and ~1.25% argon. CO2 in air is in minimal amount, ~0.05% by mass, and with minimal capacity (~2%) to influence the "Greenhouse Effect" compared to water vapor"

Nicola Scafetta
Nicola Scafetta
Nicola Scafetta is a research scientist at Duke University Physics Department. His research interests are in theoretical and applied statistics and nonlinear models of complex processes...

, research scientist in the physics department at Duke University
Duke University
Duke University is a private research university located in Durham, North Carolina, United States. Founded by Methodists and Quakers in the present day town of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco industrialist James B...

:"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."

Nir Shaviv
Nir Shaviv
Nir Joseph Shaviv is an Israeli/American physics professor, carrying out research in the fields of astrophysics and climate science. He is currently an associate professor at the Racah Institute of Physics of the Hebrew University of Jerusalem....

, astrophysicist at the Hebrew University of Jerusalem
Hebrew University of Jerusalem
The Hebrew University of Jerusalem ; ; abbreviated HUJI) is Israel's second-oldest university, after the Technion – Israel Institute of Technology. The Hebrew University has three campuses in Jerusalem and one in Rehovot. The world's largest Jewish studies library is located on its Edmond J...

:"[T]he truth is probably somewhere in between [the common view and that of skeptics], with natural causes probably being more important over the past century, whereas anthropogenic causes will probably be more dominant over the next century. ... [A]bout 2/3's (give or take a third or so) of the warming [over the past century] should be attributed to increased solar activity and the remaining to anthropogenic causes."

Fred Singer
Fred Singer
Siegfried Fred Singer is an Austrian-born American physicist and emeritus professor of environmental science at the University of Virginia...

, Professor emeritus of Environmental Sciences at the University of Virginia
University of Virginia
The University of Virginia is a public research university located in Charlottesville, Virginia, United States, founded by Thomas Jefferson...

:"The greenhouse effect
Greenhouse effect
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere...

is real. However, the effect is minute, insignificant, and very difficult to detect." “It’s not automatically true that warming is bad, I happen to believe that warming is good, and so do many economists.”

Willie Soon
Willie Soon
Willie Wei-Hock Soon is an astrophysicist at the Solar and Stellar Physics Division of the Harvard-Smithsonian Center for Astrophysics. Soon has testified before Congress on the issue of climate change He is known for his views that most global warming is caused by solar variation...

, astrophysicist, Harvard-Smithsonian Center for Astrophysics
Harvard-Smithsonian Center for Astrophysics
The Harvard–Smithsonian Center for Astrophysics is one of the largest and most diverse astrophysical institutions in the world, where scientists carry out a broad program of research in astronomy, astrophysics, earth and space sciences, and science education...

. "[T]here's increasingly strong evidence that previous research conclusions, including those of the United Nations and the United States government concerning 20th century warming, may have been biased by underestimation of natural climate variations. The bottom line is that if these variations are indeed proven true, then, yes, natural climate fluctuations could be a dominant factor in the recent warming. In other words, natural factors could be more important than previously assumed."

Roy Spencer, principal research scientist, University of Alabama in Huntsville
University of Alabama in Huntsville
The University of Alabama in Huntsville is a state-supported, public, coeducational research university, located in Huntsville, Alabama, United States, is accredited by the Southern Association of Colleges and Schools to award baccalaureate, master's and doctoral degrees, and is organized in five...

:"I predict that in the coming years, there will be a growing realization among the global warming research community that most of the climate change we have observed is natural, and that mankind’s role is relatively minor".

Henrik Svensmark
Henrik Svensmark
Henrik Svensmark is a physicist at the Danish National Space Center in Copenhagen who studies the effects of cosmic rays on cloud formation. His work presents hypotheses about solar activity as an indirect cause of global warming; his research has suggested a possible link through the interaction...

, Danish National Space Center
Danish National Space Center
The Danish National Space Center is a Danish sector research Institute and a part of the Danish Ministry of Science, Technology and Innovation. It is located in Copenhagen at Østerbro...

:"Our team ... has discovered that the relatively few cosmic rays that reach sea-level play a big part in the everyday weather. They help to make low-level clouds, which largely regulate the Earth’s surface temperature. During the 20th Century the influx of cosmic rays decreased and the resulting reduction of cloudiness allowed the world to warm up. ... most of the warming during the 20th Century can be explained by a reduction in low cloud cover."

Jan Veizer
Jan Veizer
Ján Veizer is the Distinguished University Professor of Earth Sciences at the University of Ottawa and Institute for Geology, Mineralogy und Geophysis, of Bochum Ruhr University, he held the NSERC/Noranda/CIFAR Industrial Chair in Earth System Isotope and Environmental Geochemistry until 2004...

, environmental geochemist, Professor Emeritus from University of Ottawa
University of Ottawa
The University of Ottawa is a bilingual, research-intensive, non-denominational, international university in Ottawa, Ontario. It is one of the oldest universities in Canada. It was originally established as the College of Bytown in 1848 by the Missionary Oblates of Mary Immaculate...

:"At this stage, two scenarios of potential human impact on climate appear feasible: (1) the standard IPCC model ..., and (2) the alternative model that argues for celestial phenomena as the principal climate driver. ... 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."

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
Syun-Ichi Akasofu
is the Founding Director of the International Arctic Research Center of the University of Alaska Fairbanks , serving in that position from the center's establishment in 1998 until January 2007. Previously he had been director of the university's Geophysical Institute from 1986.-Background:Akasofu...

, retired professor of geophysics and Founding Director of the International Arctic Research Center of the University of Alaska Fairbanks:"[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."

Claude Allègre
Claude Allègre
Claude Allègre is a French politician and scientist.- Scientific work :The main scientific area of Claude Allègre is geochemistry....

, geochemist, Institute of Geophysics (Paris):"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."

Robert C. Balling, Jr.
Robert Balling
Robert C. Balling, Jr. is a professor of geography at Arizona State University, and the former director of its Office of Climatology. His research interests include climatology, global climate change, and geographic information systems...

, a professor of geography at Arizona State University
Arizona State University
Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...

:"[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."

John Christy
John Christy
John R. Christy is a climate scientist at the University of Alabama in Huntsville whose chief interests are satellite remote sensing of global climate and global climate change. He is best known, jointly with Roy Spencer, for the first successful development of a satellite temperature...

, professor of atmospheric science and director of the Earth System Science Center at the University of Alabama in Huntsville
University of Alabama in Huntsville
The University of Alabama in Huntsville is a state-supported, public, coeducational research university, located in Huntsville, Alabama, United States, is accredited by the Southern Association of Colleges and Schools to award baccalaureate, master's and doctoral degrees, and is organized in five...

, contributor to several IPCC
Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...

reports:"...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." "...the data show a small underlying positive trend that is consistent with CO2 climate forcing with no-feedback. ... The global warming hypothesis 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."

Petr Chylek
Petr Chylek
Petr Chylek is a researcher for Space and Remote Sensing Sciences atLos Alamos National Laboratory. Prior to becoming a government researcher in 2001, Chylek was Professor of Physics and Atmospheric Science in the graduate program at Dalhousie University in Halifax, Canada where he continues as an...

, Space and Remote Sensing Sciences researcher, Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

: "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"

David Deming
David Deming
David Deming , an American geologist and geophysicist, is an associate professor of Arts and Sciences at the University of Oklahoma in Norman. He graduated from North Central High School in Indianapolis, Indiana in 1972. He graduated from Indiana University in 1983 with a BS degree in geology, and...

, geology professor at the University of Oklahoma
University of Oklahoma
The University of Oklahoma is a coeducational public research university located in Norman, Oklahoma. Founded in 1890, it existed in Oklahoma Territory near Indian Territory for 17 years before the two became the state of Oklahoma. the university had 29,931 students enrolled, most located at its...

:"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."

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.

Ivar Giaever
Ivar Giaever
Ivar Giaever is a physicist who shared the Nobel Prize in Physics in 1973 with Leo Esaki and Brian Josephson "for their discoveries regarding tunnelling phenomena in solids". Giaever's share of the prize was specifically for his "experimental discoveries regarding tunnelling phenomena in ......

, Nobel Laureate in physics and professor emeritus at Rensselaer Polytechnic Institute: "In the APS
American Physical Society
The American Physical Society is the world's second largest organization of physicists, behind the Deutsche Physikalische Gesellschaft. The Society publishes more than a dozen scientific journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than 20...

it is ok to discuss whether the mass of the proton changes over time and how a multi-universe behaves, but the evidence of global warming is incontrovertible? The claim (how can you measure the average temperature of the whole earth for a whole year?) is that the temperature has changed from ~288.0 to ~288.8 degree Kelvin in about 150 years, which (if true) means to me is that the temperature has been amazingly stable, and both human health and happiness have definitely improved in this 'warming' period."

Craig D. Idso
Craig D. Idso
Craig D. Idso is the founder and chairman of the board of the Center for the Study of Carbon Dioxide and Global Change.He is the brother of Keith E. Idso and son of Sherwood B. Idso....

, faculty researcher, Office of Climatology, Arizona State University
Arizona State University
Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...

and founder of the Center for the Study of Carbon Dioxide and Global Change
Center for the Study of Carbon Dioxide and Global Change
The Center for the Study of Carbon Dioxide and Global Change is a 501 non-profit organization based in Arizona in the United States...

:"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." (May 2007)

Sherwood Idso, former research physicist, USDA
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...

Water Conservation Laboratory, and adjunct professor, Arizona State University
Arizona State University
Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...

:"[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." (2003) "If strong positive feedbacks existed, the Earth would likely exhibit a radically unstable climate, significantly different from what has characterized the planet over the eons." The warming of the last hundred years is seen to be basically a recovery from the global chill of the Little Ice Age
Little Ice Age
The Little Ice Age was a period of cooling that occurred after the Medieval Warm Period . While not a true ice age, the term was introduced into the scientific literature by François E. Matthes in 1939...

, which was a several-hundred-year period of significantly cooler temperatures than those of the present that persisted until the end of the nineteenth century."

Patrick Michaels
Patrick Michaels
Patrick J. Michaels is an American climatologist. Michaels is a senior research fellow for Research and Economic Development at George Mason University, and a senior fellow in environmental studies at the Cato Institute...

, Senior Fellow at the Cato Institute
Cato Institute
The Cato Institute is a libertarian think tank headquartered in Washington, D.C. It was founded in 1977 by Edward H. Crane, who remains president and CEO, and Charles Koch, chairman of the board and chief executive officer of the conglomerate Koch Industries, Inc., the largest privately held...

and retired research professor of environmental science at the University of Virginia
University of Virginia
The University of Virginia is a public research university located in Charlottesville, Virginia, United States, founded by Thomas Jefferson...

:"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." (October 16, 2003)

Dead scientists

The lists above only include living scientists. The following are dead. Their views on climate change are usually described in more detail in their biographical articles.

August H. "Augie" Auer Jr. (1940–2007), retired New Zealand MetService
Meteorological Service of New Zealand Limited
Meteorological Service of New Zealand Limited was established as a State-Owned Enterprise in 1992. It employs about 215 staff and its headquarters are in Wellington, New Zealand...

Meteorologist and past professor of atmospheric science at the University of Wyoming, believed that the cause of global warming was unknown: [Computer modeling results gave] "usually an envelope of figures, one which said the planet could warm 6 deg in the next 100 years and the other end of the envelope was perhaps half a deg in 100 years. And you know which one would be quoted" [in the media] ... "So if you multiply the total contribution 3.6 by the man-made portion of it, 3.2, you find out that the anthropogenic contribution of to the global greenhouse effect is 0.117 percent, roughly 0.12 percent, that's like 12c in $100." "'It's miniscule ... it's nothing,'".

Reid Bryson
Reid Bryson
Reid Bryson was an American atmospheric scientist, geologist and meteorologist. He was a professor emeritus of the University of Wisconsin–Madison. He completed a B.A. in geology at Denison University in 1941 and a Ph.D. in meteorology from University of Chicago in 1948...

(1920–2008), Emeritus Professor of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, believed global warming was primarily caused by natural processes:"It’s absurd. Of course it’s going up. It has gone up since the early 1800s, before the Industrial Revolution, because we’re coming out of the Little Ice Age
Little Ice Age
The Little Ice Age was a period of cooling that occurred after the Medieval Warm Period . While not a true ice age, the term was introduced into the scientific literature by François E. Matthes in 1939...

, not because we’re putting more carbon dioxide into the air."

Marcel Leroux
Marcel Leroux
Marcel Leroux was a French climatologist, a former Professor of Climatology at Jean Moulin University in Lyon, France, and director of the Laboratory of Climatology, Risk, and Environment....

(1938–2008) former Professor of Climatology, Université Jean Moulin
University of Lyon
The University of Lyon , located in Lyon and Saint Etienne, France, is a center for higher education and research comprising 16 institutions of higher education...

, believed global warming was primarily caused by natural processes:"The possible causes, then, of climate change are: well-established orbital parameters on the palaeoclimatic scale, ... solar activity, ...; volcanism ...; and far at the rear, the greenhouse effect, and in particular that caused by water vapor, the extent of its influence being unknown. These factors are working together all the time, and it seems difficult to unravel the relative importance of their respective influences upon climatic evolution. Equally, it is tendentious to highlight the anthropic factor, which is, clearly, the least credible among all those previously mentioned."

Frederick Seitz
Frederick Seitz
Frederick Seitz was an American physicist and a pioneer of solid state physics. Seitz was president of Rockefeller University, and president of the United States National Academy of Sciences 1962–1969. He was the recipient of the National Medal of Science, NASA's Distinguished Public Service...

(1911–2008), solid-state physicist
Solid-state physics
Solid-state physics is the study of rigid matter, or solids, through methods such as quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the large-scale properties of solid materials result from...

and former president of the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...

believed global warming was primarily caused by natural processes: "The first thing to note is that the 100 years of global warming occurred in two stages--a temperature rise of approximately a half-degree Fahrenheit early in the century from 1910 to 1940, and another half-degree temperature rise toward the end of the century in the 1980s and 1990s. Between these two periods of warming, from the 1940s to the 1970s, the Earth actually cooled somewhat. Greenhouse gases like carbon dioxide cannot cool the planet; they can only warm it... The fact that the cooling in the 1950s and 1960s is a feature of the temperature records of both hemispheres indicates that the absence of the predicted global warming cannot be due to aerosols."

External links

Intergovernmental Panel on Climate Change (IPCC) — Consensus, mainstream assessment of climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
Nongovernmental International Panel on Climate Change (NIPCC) — Compilation of some non-consensus views and study references