“The era of global boiling has arrived”, stated Antonio Guterres at a July press conference last year. This proclamation by the Secretary-General of the United Nations was representative of the marked increase in magnitude, frequency and vehemence of climate change alarm bells ringing since 2023, heralding extreme doom and gloom – and all reportedly caused by humankind. The situation has gotten so dire, notable climate scientist James Hansen reported that governments must not only “impose carbon fees” (read: taxes) to “rapidly draw down [carbon dioxide] emissions”, but they must also “deploy techniques to reduce incoming solar radiation”. Or, in layman’s terms, blot out the sun.

Since nearly every human activity emits carbon dioxide, including breathing, and the sun’s rays are the source of energy for all life on our planet, these drastic and extreme actions – which call for trillions of dollars of funding – warrant requiring rock-solid evidence, an absolute certainty that this is what must be done to stave off devastation. Accordingly, it would not be amiss to look at the situation we find ourselves in and wonder – how exactly do we know that humans are causing this unprecedentedly disastrous level of climate change? What are the precise facts this conclusion is based on?

How exactly do we know that humans are causing this unprecedentedly disastrous level of climate change? What are the precise facts this conclusion is based on?

Thus, we embark on a journey to find out the manner in which the theory of anthropogenic global warming has been validated as being in accordance with reality. The result, we shall see, is both shocking and dismaying. The theory of anthropogenic human warming ultimately rests on an unproven hypothesis that carbon dioxide and other so-called greenhouse gases in the atmosphere cause the Earth’s surface to warm up due to something called the “greenhouse effect”, an effect alleged to be so powerful that without it our planet would be an uninhabitable frozen ball. This makes it all the more peculiar that nobody has been able to experimentally demonstrate and therefore verify the greenhouse effect. The evidence that is provided consists mainly of models which already presume the greenhouse effect, and therefore assume a theory in which the conclusion is part of the premise. This is further corroborated by observational data which can never empirically distinguish the cause and the effect of greenhouse gases. Worst of all, the alleged recent warming trend that is said to confirm earlier model predictions is based on data that appears to be adjusted to match the very models it is meant to be independently corroborating.

The evidence that is provided consists mainly of models which already presume the greenhouse effect, and therefore assume a theory in which the conclusion is part of the premise.

What lies at the core of climate science is thus a fundamental vacuity, a net of assumptions and circular self-referencing in lieu of a firm foundation. This is highly relevant because it means our current climate scare is based not on irrefutable scientific evidence but rather on hysteria and alarmist fear-mongering that fifty years of “failed apocalyptic predictions” have failed to abate. This is crucial to understand as it makes it clear that rather than debating how humans should mitigate this alleged impending disaster, the proper focus should be to question why those in power are employing psychological fear tactics to promote taxation, restriction and degrowth, and why so many intelligent people have uncritically bought into the hysteria when these proposed policies are clearly to their own detriment.

The “Unrivaled Authority on Climate Science”

The Intergovernmental Panel on Climate Change (IPCC) has established itself as “the world’s unrivaled authority on climate science”. It is illustrative to see how all roads eventually lead to the IPCC. For example, one of the first results when googling “carbon dioxide causes global warming” is an article that reports “more than a 25 per cent [recent] increase in radiative forcing – the warming effect on our climate – because of carbon dioxide”. But they do not demonstrate this themselves. Instead, they cite a bulletin by the WMO (World Meteorological Organization). The cited bulletin in turn reports that CO2 accounted “for about 80%” of the increase in “radiative forcing by long-lived greenhouse gases”, but they are merely relaying the figures from “[t]he National Oceanic and Atmospheric Administration (NOAA) Annual Greenhouse Gas Index [(AGGI)]”. The AGGI’s webpage affirms that CO2 is “largely responsible for the observed increases in global temperature”, but in lieu of demonstrating this themselves, the authors cite another 2021 report by the IPCC. Other top search results lead to the IPCC in a similar manner. It thus behooves us to look there for the proof for these claims.

The IPCC’s proof

NOAA’s citation leads to the IPCC’s Sixth Assessment Report 2021. The relevant section is Chapter 7, where we learn that radiative forcing is a “concept” which serves to “quantify” various “perturbations to Earth’s top-of-atmosphere energy budget”, the purpose of which is to quantify all the “major energy flows” in the atmosphere. Figure 7.2 provides a helpful visual representation of it, and here we see something a bit odd. The total energy flowing out of the surface is more than three times larger than the amount flowing into it from the sun. The deficit is made up by additional energy coming down from the atmosphere labeled “greenhouse gases”, which are gases that absorb and emit thermal radiation in the range that the Earth’s surface emits. The IPCC’s first report confirms this understanding: “[The absorbed solar] radiation warms the Earth’s surface which then emits energy […] [greenhouse gases] are able to absorb this radiation [energy] and subsequently emit it both upwards to space and downwards to the surface. This downward emission of radiation serves to further warm the surface. This warming is known as the greenhouse effect.” (Chapter 2, p. 48).

Thus “radiative forcing” is a marginal increase in this downwards energy flow which serves to warm the surface even more. However, the described mechanism is rather puzzling. In normal sensate reality, heat only flows from hot to cold. The Sun heats the Earth’s surface which then becomes hotter than the atmosphere. The surface, in turn, heats the cooler atmosphere, with the air being warmest closest to the surface and progressively cooling with elevation. The greenhouse effect appears to involve an additional inverted heat flow within this system. In it, the colder atmosphere causes a further warming of the hotter surface that initially warmed it in the first place. The magnitude is such that the atmosphere is responsible for heating the surface twice as much as the Sun, which is rather at odds with the everyday experience of the feeling of direct sunlight on one’s skin as compared with the night sky or a cloudy day.

In normal sensate reality, heat only flows from hot to cold, but the greenhouse effect appears to involve an inverted heat flow within this system. 

Gerlich et al. 2007 argue (and later defend) that “[a]ccording to the second law of thermodynamics, such a planetary machine can never exist”. Miskolczi 2023 asserts that the energy budget ignores many “fundamental concepts and principles of theoretical physics” and notes that “the complexity of the climate system is not a free ticket for violating the first principles of physics.”

Despite easily-rebutted claims of a settled scientific consensus, the fact that scientists continue to question the physicality of the proposed mechanism indicates it has not been irrefutably established yet, despite allegedly being easy to demonstrate. Although the burden of proof is on a theory’s proponents rather than its critics, we can conjecture what one such proof might look like: it would have to consist of an external energy source – such as the sun or a heat lamp – that is set to warm a surface. The energy input should be measured and the surface, in the presence of greenhouse gases, should get much hotter than that input alone can provide, emitting much more energy in response. This would definitively demonstrate the greenhouse effect itself, after which the anthropogenic influence could be gauged by introducing more carbon dioxide into the apparatus and measuring the marginal temperature response.

But we find that the IPCC itself does not provide any evidence of this sort. Instead, it kicks the can down the road to the peer-reviewed literature, where presumably the evidence lies. 

The peer-reviewed literature’s proof

The IPCC’s latest forcing value for CO2 comes from Etminan 2016. However, the entire paper consists entirely of calculations done via “code[s]”, “models”, and “simulations” without empirical validation. The earlier work it is based on, Myhre 1998, is more of the same – an updated calculation without empirical validation. In both cases the new values are simply corroborated by having “overall good agreement” with earlier expressions. The problem, however, is that without empirical validation, there is no way of knowing if a model is correct. For example, Boyle’s law is a simple equation. It was experimentally determined in 1662, relating various properties of a gas, such as its pressure and volume. Yet in the 19th century, American Meter found that at higher gas pressures, Boyle’s law was incorrect. New equations via further experiments had to be developed. No model built around Boyle’s law could have predicted them. Any such model would simply be wrong, and without empirical validation, there would be no way of knowing if it is right or wrong.

In the 19th century, American Meter found that at higher gas pressures, Boyle’s law was incorrect. No model built around Boyle’s law could have predicted that without empirical validation.

Kramer et al 2021 confirm that empirical evidence is lacking. They report that “instantaneous radiative forcing […] has not been directly observed globally” and that “previous estimates have come from models”. Yet they acknowledge that satellites cannot actually measure this metric, and apply a technique called “radiative kernels” to “disentangle” the metric from the raw data. The problem is that these kernels are themselves calculated using models. Thus the “observational evidence” they present is circular, as it actually consists of data that has been processed through the very models it is meant to be corroborating.

Going further back, we see that earlier papers attempt to provide empirical validation. Yet these attempts are ultimately unsatisfying. Myhre 1998 defers to Hansen 1988 for evidence – the same Hansen who now wants to blot out the Sun. Hansen’s paper in turn relies entirely on two legs of evidence from earlier climate models. The first is a general formula for radiative forcing based on a model in Lacis et al 1981, whose authors conclude that “the observed global temperature change in the 1970’s […] is too small to be confidently ascribed to the greenhouse effect.” This certainly does not constitute rock-solid evidence. Regardless of its poor findings, this very paper is one of the foundations for most climate change claims that followed. 

The second leg of evidence consists of predictions based on a model from Hansen et al 1983. That model was empirically validated by a hind-casting process, comparing its model outputs for a four-month period in the past with observations during the same time. This does not prove the proposed causal mechanism the model relies on, just that with sufficient tuning of its many variables, the model can be made to match some historical values. The problem this poses is best exemplified by going back to Pekeris 1932. (It must be noted that Hansen et al 1983 cites Wang 1976 which cites Goody 1964 who then cites Pekeris 1932). In Pekeris, the models of the time led the scientist to believe that “it becomes plausible the temperatures on […] Venus, Earth, and Mars are about the same”. As Venus’s temperature is 464ºC while that of Mars is -63ºC, his egregious error reveals the fundamental problem of not having experimental means by which to validate models. This leads to a situation where models are susceptible to overfitting available data, with no ability to check their operations by proving that the actual effect matches the model’s prediction. 

In Pekeris 1932, the models of the time led the scientist to believe that “it becomes plausible the temperatures on […] Venus, Earth, and Mars are about the same”. Venus’s temperature, it turned out, is 464ºC while that of Mars is -63ºC. 

Another approach climate modelers take to make up for this fundamental lack is by way of a metric called “equilibrium climate sensitivity”, defined as how much warmer the surface will get as a result of doubling CO2 concentrations. This is easily computed with models by doubling the simulated CO2 levels, running the model, and seeing what happens. Hansen even calls these simulations “experiments” even though they are nothing of the sort. The results are then compared to various observational lines of evidence. For example, Hansen et al 1988 cites Hansen et al 1984, which compares the Hansen et al 1983 model’s values with two other approaches. The first is by analyzing historical data related to the last Ice Age. Yet the historical reconstruction itself requires various assumptions and is corroborated by comparing it with estimates from climate models, and the analysis entails running the model itself over this reconstructed data, which makes it a circular exercise. The other approach is to assume that the “estimated global warming” between 1850-1980 was due to an “estimated” CO2 growth between the same, which results in a climate sensitivity within the range of the other approaches. But the assumption that higher CO2 levels cause a temperature increase is the same premise the model relies on, so this approach cannot do what it intends, which is to prove the premise. It merely tells us that if the premise is true, and if the entirety of the estimated warming was due to the premise, the model would be correct in its calculated effects.

Correlation is not causation

The fundamental reason that observations can’t replace experiments is that they can only ever show correlation, not causation. As a piquant example, the number of library assistants in North Dakota is highly correlated with Norway’s petroleum consumption. A causal link between the two is rather implausible. Besides this, there are a number of reasons that recent CO2 levels may be correlated with higher temperatures such as El Nino/La Nina cycles, an observed recent reduction in clouds reflecting sunlight, and changes in solar activity. Looking at longer time scales calls the general theory into question: Barral 2017 shows that CO2 levels sometimes show “inverse trends” with temperature, and Easterbrook 2016 found evidence that “global warming causes increased atmospheric CO2”, and not vice-versa.

The assumption that higher CO2 levels cause a temperature increase is the same premise the model relies on, so this approach cannot do what it intends, which is to prove the premise.

Even more egregious than this is the compelling evidence that recent temperature trends are being artificially adjusted to be more in line with model predictions. In 1989, the director of NOAA noted a cooling trend from 1921-1979, yet NOAA’s graphs for that same period today show a warming trend. NOAA openly reports that they adjust temperatures using a “pairwise homogenization algorithm”, yet this algorithm was not empirically calibrated but rather chosen based on how well it reverses randomly-added noise. Its net effect is to cool the past and warm the present in a manner nearly perfectly correlated with changes in CO2 concentrations. In other words, the adjustments – applied to over 52% of the monthly data points in 2023 – alter the data to better match what the radiative transfer models say should happen. This makes one wonder why more of the vast quantity of funding is not going towards something as basic and essential as accurately measuring temperatures.

The only fundamental way to alleviate these doubts is with experimental evidence. But not only is none provided for the calculated radiative forcing and climate sensitivity values – there is none for the greenhouse effect itself, as a physical mechanism independent of its effect on the global climate. 

No experimental evidence has ever been provided for the “greenhouse effect”.

As Harde 2022 indicates, scientists “are missing a reliable experimental verification of this effect”, and their own claim to have done so is refuted in Seim 2023. In addition to this, there are various real-world examples directly providing evidence against the greenhouse effect. It thus appears that as far as anybody has been able to show, the greenhouse effect that explains “warming” exists only in climate models and not in reality.

Origins of the Theory

If the greenhouse effect has never been demonstrated, then why does anybody believe that CO2 causes warming in the first place? The answer is somewhat embarrassing. The first to propose the effect was Fourier in 1824, who (according to Arrhenius) believed that an actual greenhouse works “because it lets through the light rays of the sun but retains the dark rays [i.e. infrared radiation] from the ground”. Fourier proposed the atmosphere had a similar property. When Tyndall discovered in 1859 that CO2 does indeed absorb infrared radiation, early climate modelers took this fact and ran with it, with Arrhenius doing “the first calculation of the warming of Earth due to CO2 increase” in 1896. But actual greenhouses do not work this way. They work by physically blocking hot air from escaping and mixing with the outside air. This was shown by R W Wood as early as 1909. It is more than strange that despite this falsification, and a lack of any further proof, the theory has persisted to this day.

Today, climate scientists and policy makers tell us that modern industry, which has elevated much of humanity to unprecedented levels of prosperity, must be heavily curtailed because it is causing catastrophic global warming due to its CO2 emissions. But the evidence provided does not warrant their level of certitude and belief, despite their assertions to the contrary. It thus behooves us to cease uncritically accepting and endorsing their proposed policies, which have caused and will likely continue to cause great harm, and restore sensibility to environmental policy making.

Dale Cloudman

Dale Cloudman is a computer scientist based in Europe. He writes under a pseudonym.

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The above article has been linked to on themotte.org and generated numerous online comments. The author addressed and refuted every single one.