# The claim that human-caused climate change is a hoax, or that its scientific consensus was manufactured, is contradicted by overwhelming and independent physical evidence

**Verdict: Contradicted.** Two separate claims are bundled here, and both fail. The first is that human-caused warming is a hoax; the second is that the widely cited scientific consensus was invented or rigged. Neither survives contact with the record. Multiple independent teams, using different methods and datasets, keep converging on the same result: among climate papers that take a position, roughly 97% (Cook et al. 2013) to more than 99% (Lynas et al. 2021) endorse human-caused warming. That consensus is not the argument for warming; it is a description of where the physical evidence has driven researchers. The evidence itself is direct and multi-stranded: the instrumental temperature record, the isotopic fingerprint of atmospheric CO2 showing a fossil origin, satellite measurements, and rising ocean heat content. NASA, NOAA, and the IPCC all state the human role plainly, with the IPCC's 2021 assessment calling human influence on warming unequivocal. What to do about it is a genuine and open policy debate. Whether it is happening, and whether humans are the main cause, is not.

Category: Science, Space & Technology · Era: 2000s · First circulated: Organized doubt about the science took shape in the late 1990s and early 2000s, notably a 1998 American Petroleum Institute communications plan and a 2002 Republican strategy memo by Frank Luntz urging politicians to keep scientific uncertainty a ‘primary issue’; the blunt ‘hoax’ framing spread widely in the 2010s. · Believed by: A minority of the public in most surveyed countries, concentrated in some political constituencies, holds that warming is exaggerated, natural, or a hoax. The reverse is true among publishing climate scientists, where the endorsement of a human role runs from about 97% to above 99% across independent studies.
URL: https://theconspiratory.com/theory/climate-change-hoax

## Summary
Two related claims circulate: that human-caused climate change is a deliberate hoax, and that the ‘97% consensus’ so often quoted was fabricated or is a statistical trick. This file treats both as testable and finds both unsupported. The 97% figure comes from Cook et al. (2013), which examined nearly 12,000 abstracts and found that, among those taking a position on human-caused warming, about 97% endorsed it; later work by Lynas and colleagues (2021) put the figure above 99%. Critics are right that most abstracts state no position, and that point is engaged here honestly, but it does not overturn the result. More important, consensus is downstream of evidence, not a substitute for it: the instrumental record, the fossil fingerprint in atmospheric CO2, satellite data, and ocean heat content independently establish that the planet is warming and that human emissions are the main cause. The tone throughout is evidence-first: what to do about warming is politics; whether it is occurring is settled science.

## The claim
That human-caused global warming is either an outright hoax or a wildly overstated scare, that the famous ‘97% of scientists agree’ statistic was manufactured or manipulated to manufacture a false consensus, and that dissent has been suppressed. In its stronger form the claim holds that the climate is not warming meaningfully at all, or that any warming is natural; in its weaker form it concedes some warming but denies that humans are the primary driver.

## Origin and timeline
- 1896: Swedish chemist Svante Arrhenius publishes a calculation of how much rising atmospheric carbon dioxide would warm Earth's surface, building on earlier work by John Tyndall and Eunice Foote on the heat-trapping properties of gases. The basic physics linking CO2 to warming predates the modern political debate by more than a century.
- 1958: Charles David Keeling begins continuous measurements of atmospheric CO2 at Mauna Loa, Hawaii. The resulting ‘Keeling Curve’ documents a steady, year-on-year rise in carbon dioxide, one of the most-replicated measurements in earth science.
- 1988: NASA scientist James Hansen tells a US Senate committee that human-driven warming is already detectable, and the World Meteorological Organization and UN Environment Programme establish the Intergovernmental Panel on Climate Change (IPCC) to assess the science.
- 1998: A leaked American Petroleum Institute ‘Global Climate Science Communications Plan’ defines victory as the point at which ‘average citizens understand uncertainties in climate science’, an explicit strategy to promote the perception of doubt.
- 2002: A strategy memo by pollster Frank Luntz advises Republican politicians that ‘should the public come to believe that the scientific issues are settled, their views about global warming will change’, and urges them to keep the lack of scientific certainty a primary issue. Historians of the period, including Naomi Oreskes and Erik Conway, later document these doubt campaigns in Merchants of Doubt.
- 2009-11: Thousands of emails stolen from the University of East Anglia's Climatic Research Unit are published, and quoted phrases such as ‘hide the decline’ are promoted as proof of fraud, the episode dubbed ‘Climategate’. Multiple independent inquiries in the following two years clear the scientists of manipulating data or subverting peer review.
- 2012-11-06: Businessman Donald Trump, later US president, posts that ‘the concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive’, a widely shared expression of the ‘hoax’ framing.
- 2013-05: Cook et al. publish ‘Quantifying the consensus on anthropogenic global warming in the scientific literature’ in Environmental Research Letters, reporting that about 97.1% of abstracts taking a position endorse human-caused warming. The paper becomes the single most-quoted, and most-attacked, source for the ‘97%’ figure.
- 2021: The IPCC's Sixth Assessment Report states that it is ‘unequivocal that human influence has warmed the atmosphere, ocean and land’, and Lynas et al. report that more than 99% of peer-reviewed papers agree humans are causing climate change.

## The evidence, claim by claim
- Claim: The 97% figure is a fraud because two-thirds of the papers Cook studied took no position at all on human-caused warming.
  Evidence: The factual premise is accurate; the conclusion is not. Of the 11,944 abstracts Cook et al. examined, about 66% expressed no position on the cause of warming, and the 97% is calculated among the roughly one-third that did. That is a defensible way to measure a consensus, not a trick: as agreement on a question becomes routine, papers stop restating it, just as astronomy papers no longer argue that Earth orbits the Sun. Critics such as economist Richard Tol reworked the data and got a still-large majority; Tol himself wrote that ‘there is no doubt in my mind that the literature on climate change overwhelmingly supports’ a human cause. As a check, Cook's team also asked the papers' own authors to rate them, and that independent method returned the same 97%.
- Claim: It is just one study, so the whole consensus rests on a single disputed paper.
  Evidence: It does not. The 97% result is one of several independent estimates that converge. Powell's abstract surveys, Cook et al.'s 2016 ‘consensus on consensus’ synthesis of seven separate studies, and Lynas et al.'s 2021 analysis of a random sample of recent literature all land in the same place, with Lynas putting the figure above 99%. Different teams, different datasets, different methods, same answer. A conclusion that survives that many independent replications is the opposite of a fabricated one.
- Claim: Consensus is not science. Truth is not decided by a show of hands, so the whole framing is an appeal to authority.
  Evidence: This is the strongest version of the objection, and it contains a real point that is then misapplied. Science is not settled by voting, and a lone dissenter can in principle be right. But the climate consensus is not a poll of opinion; it is a measure of where the physical evidence has pushed the people who study it most closely. The consensus is a symptom of the evidence, not the argument for it. If every survey vanished tomorrow, the instrumental temperature record, the CO2 fingerprint, the satellite data, and ocean heat content would still show the same thing. The consensus matters as a signal to non-experts, but it is not load-bearing for the underlying science.
- Claim: The rise in CO2 is natural, from volcanoes or the oceans, not from burning fossil fuels.
  Evidence: The carbon carries its own signature, and it points to fossil fuels. Coal, oil, and gas were buried for millions of years, so they contain no radiocarbon (carbon-14) and are relatively poor in carbon-13. As the atmosphere's CO2 has risen, its carbon-14 content has fallen and its carbon-13 ratio has shifted, exactly the isotopic dilution expected from adding ancient carbon. NOAA and NASA describe this as a fingerprint: volcanoes emit far less CO2 than human activity each year, and the ocean has been a net absorber, not a source. The measured rise tracks cumulative fossil-fuel emissions.
- Claim: The planet has not really warmed, or any warming stopped, so the crisis is invented.
  Evidence: Multiple independent records disagree. Surface thermometer datasets kept separately by NASA, NOAA, the UK Met Office, and others show roughly 1.1 to 1.2 degrees Celsius of warming since the late 19th century, and they agree closely despite being compiled by different groups. Satellite measurements of the lower atmosphere show warming as well. Because more than 90% of the excess heat goes into the oceans, ocean heat content is arguably the cleaner yardstick, and it has risen steadily and to record levels. The much-quoted early-2000s ‘pause’ was a short-term fluctuation within a continuing long-term rise, not a halt.
- Claim: The ‘Climategate’ emails exposed scientists fudging the data, proving the whole field is corrupt.
  Evidence: The emails were real; the fraud was not. Phrases such as ‘hide the decline’ referred to a known, published issue about tree-ring proxies diverging from thermometer data after 1960, not to concealing global temperatures. At least eight independent investigations, in the UK and the US, examined the emails and the scientists' conduct. All concluded there was no manipulation of data or corruption of peer review that undermined the science, though some criticized a lack of openness. The underlying temperature findings were subsequently reproduced by independent teams, including one (Berkeley Earth) initially funded partly by climate-skeptic sources.
- Claim: Scientists have a financial incentive to hype the danger to keep grant money flowing.
  Evidence: The incentives run the other way, and the accusation is asymmetric. The most heavily documented funding campaigns are those that promoted doubt, financed by parts of the fossil-fuel industry, as the 1998 API plan and the 2002 Luntz memo make explicit. Climate research is conducted by tens of thousands of scientists across dozens of countries with different governments, funders, and rivalries; the surest route to fame in science is overturning a consensus, not maintaining it. No one has produced the evidence that would do so, despite a strong incentive to try.
- Claim: Even granting some warming, humans are not necessarily the main cause; it could be the Sun or natural cycles.
  Evidence: This is the most scientifically serious skeptic position, and it has been tested directly. If the Sun were driving recent warming, the upper atmosphere (stratosphere) would warm along with the surface; instead the stratosphere has cooled while the surface warmed, a pattern that fits greenhouse gases and not a brighter Sun. Solar output has been broadly flat or slightly declining over recent decades while temperatures climbed. Attribution studies that include natural factors (sun, volcanoes, ocean cycles) cannot reproduce the observed warming without the human-added greenhouse gases. That is why the IPCC calls the human role unequivocal.

## Why people believe it
- The policy stakes are enormous, and that colors the science for many people. Because acting on climate implies costly, contested changes to energy and economic life, doubting the diagnosis can feel like resisting the prescription. It is easier to question whether the problem is real than to argue about an expensive response, so the two get fused.
- A real, well-funded campaign taught the public to see uncertainty. Documented efforts by parts of the fossil-fuel industry, echoing the earlier tobacco playbook, deliberately promoted the idea that the science was unsettled. Decades of that messaging left a durable residue: many people sincerely believe the debate is livelier among scientists than it actually is.
- The ‘97%’ statistic is genuinely easy to attack out of context. Because most abstracts take no explicit position, a critic can truthfully say ‘two-thirds of the papers didn't endorse it’ and sound devastating, even though the figure is a standard way to measure agreement. A claim that is easy to caricature is easy to disbelieve.
- Climate is abstract, slow, and global, which makes it hard to feel. A cold winter, a quiet hurricane season, or a single mistaken forecast can seem to contradict a trend that only shows up in decades of global averages, and that mismatch between lived weather and measured climate gives the ‘hoax’ story an intuitive hook.

## Open questions
- How sensitive the climate is to a doubling of CO2, the ‘climate sensitivity’ number, is a genuine live question in the science, with the IPCC giving a likely range rather than a single value. This is real uncertainty about how much and how fast, not about whether human-caused warming is occurring, and skeptics sometimes blur the two.
- Regional and short-term impacts remain hard to project. How warming translates into specific droughts, storms, or crop failures in a given place and decade is far less certain than the global trend, and honest communication has to keep the confident core separate from the fuzzier edges.
- The right policy response is genuinely contested and lies outside the settled science. Carbon pricing, nuclear power, adaptation versus mitigation, and how to weigh present costs against future harm are value-laden political choices. Treating those debates as if they were also settled, or treating the physical science as if it were merely political, both muddy the line this file tries to hold.
- Why the consensus is so persistently disbelieved, despite its strength, is a question about communication and trust more than about data. The gap between what scientists find and what large publics accept is one of the defining puzzles of the issue.

## Sources
- Quantifying the consensus on anthropogenic global warming in the scientific literature, Environmental Research Letters (Cook et al.) (2013): https://iopscience.iop.org/article/10.1088/1748-9326/8/2/024024
- Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature, Environmental Research Letters (Lynas et al.) (2021): https://iopscience.iop.org/article/10.1088/1748-9326/ac2966
- Consensus on consensus: a synthesis of consensus estimates on human-caused global warming, Environmental Research Letters (Cook et al.) (2016): https://iopscience.iop.org/article/10.1088/1748-9326/11/4/048002
- Scientific Consensus: Earth's Climate Is Warming, NASA Science: https://science.nasa.gov/climate-change/scientific-consensus/
- Evidence: How Do We Know Climate Change Is Real?, NASA Science: https://science.nasa.gov/climate-change/evidence/
- How do we know the build-up of carbon dioxide in the atmosphere is caused by humans?, NOAA Climate.gov: https://www.climate.gov/news-features/climate-qa/how-do-we-know-build-carbon-dioxide-atmosphere-caused-humans
- Fingerprinting fossil fuel emissions with carbon-14, NOAA Research (2020): https://research.noaa.gov/2020/06/01/fingerprinting-fossil-fuel-emissions-with-carbon-14/
- Climate Change 2021: The Physical Science Basis, Summary for Policymakers, IPCC Sixth Assessment Report, Working Group I (2021): https://www.ipcc.ch/report/ar6/wg1/chapter/summary-for-policymakers/
- More than 99.9% of studies agree: Humans caused climate change, Cornell Chronicle (2021): https://news.cornell.edu/stories/2021/10/more-999-studies-agree-humans-caused-climate-change
- Richard Tol's Attack On 97 Percent Climate Change Consensus Study Has 'Critical Errors', DeSmog (2014): https://www.desmog.com/2014/05/30/richard-tol-s-attack-97-cent-climate-change-consensus-study-has-critical-errors/

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