by Prof. Alain Préat, emeritus, Université Libre de Bruxelles
Oct 13, 2023
An obvious fact
No one denies that the Earth’s temperature has been rising slightly by around 0.9°C for almost 125 years (see Soon et al., 2023 for details). This recent increase is minimal (0.6°C between 1975 and 1998) and framed by periods of temperature decrease of similar amplitude (1880-1910 and 1940-1975).
Our media, including the IPCC and many scientists, claim that the sole culprit for the current temperature rise is atmospheric CO2 levels, which are linked to human activity. This is a hypothesis, since no link has yet been established between temperature and CO2 content – quite the contrary (Davison, 2023). The climate alarmism (Watts, 2023) that occupies the front pages of our newspapers is not justified, as we shall see.
This increase over more than a century is by no means exceptional; it has occurred many times before with much greater amplitudes, up to 20 times the recent increase, and over equally short periods. For example, in the Pleistocene (2.58 million years or ‘Ma’ to 11,700 years), researchers have counted more than 25 cycles with abrupt increases of +8°C to +16°C in 50 years each time (= ‘Dansgaard-Oeschger cycles’, see Boers, 2018, SCE, 2020 and here). These abrupt increases are to be compared with the recent increase of 0.3°C in 50 years (average 1880-2008). See SCE and SCE. Such cycles also exist in older geological periods, for example in the Jurassic (CNRS ; Boulila et al., 2022).
Several high-level journals (including Nature) have shown that the increase in CO2 follows that of temperature, mainly because of CO2 degassing in the oceans (see references in SCE, 2021). Note also that the current atmospheric CO2 content (0.04% or 400 ppm – ‘parts per million’) is twice what it was during the Dansgaard-Oeschger cycles, which last between 1,500 and 4,500 years. It’s also worth noting that current atmospheric CO2 levels are the lowest since the Earth’s existence (4.65 billion years ago), apart from a short period of 100 Ma (in the Permian-Carboniferous transitional period) with the same levels as today. For almost 2% of its history, the level of CO2 in the Earth’s atmosphere has thus varied from several thousand ppm to several percent, i.e., from 3 to 25 times higher since the Cambrian, 541 Ma ago (geological scale here), when biodiversity exploded (with metazoans, here), and even much earlier during the Precambrian (Thomas, 2000 ; Préat, 2019 ; Lehmer et al., 2020). CO2 levels were sometimes higher than today’s during ice ages. Examples of warmer and colder periods are the rule in geology; just think of the Arctic (Svarlbad) at the beginning of the Holocene, around 11,000 years ago, which was +7°C warmer than the present, when CO2 levels were half the current level (Richard, 2020).
However, the Earth has experienced many hot and cold periods in succession at different frequencies, without the slightest anthropogenic CO2 being present, since Homo sapiens appeared around 250,000 years ago, and has only been emitting CO2 on a massive scale for a few decades. We thus speak of warm Optima (Holocene, Minoan, Roman, Medieval, Modern – see SCE articles and synthesis SCE, 2022, also Spencer, 2008) for the last few thousand years and of very warm Optima or hyperthermal events for the Cenozoic (Paleocene/Eocene SCE, 2019, Eocene/Oligocene (Li et al., 2022), Middle Miocene, Lower Pliocene, Pleistocene) since 65 Ma (and more for older periods, He et al., 2023). Each time, over several centuries or millennia (or even longer), the Earth’s (and oceans’) temperature was significantly higher than today (a few degrees, and even much higher, e.g., up to 8°C to 10°C for 200,000 years during the PETM (‘Paleocene-Eocene Thermal Event’ 55.8 Ma ago, here). Drought episodes were long (several centuries or much longer, as in the Triassic period 250 Ma ago) and are well documented geologically and historically (Postel-Vinay, 2022, Smith at al., 2022). Cold periods alternate with Optima and are also well documented, with sometimes spectacular drops in temperature (from a few degrees to > 10°C). These climatic changes are quantified by numerous proxies: geological (isotopes, etc.), biological (stomata….), chemical (Be, Al….), physical (magnetic susceptibility, etc.), etc., demonstrating that climate change is as much a rule of geology as plate tectonics.
CO₂ is not responsible for temperature variations
CO2, the IPCC’s and the media’s number 1 culprit, has little to do with global warming. This is also confirmed by the evolution of the temperature of the lower atmosphere since 1895 (+1.15°C in 128 years) over the entire American continent (USA). Global temperature (USA) is not correlated with atmospheric CO2 levels, or even with anthropogenic CO2 emissions (SCE, 2023). The annual increase in CO2 levels is currently 0.002% since the beginning of this century, which is very minimal on an atmospheric scale, and only 40% remains in the atmosphere. It should also be noted that an average global temperature for the Earth makes no physical sense, as temperature is an intensive quantity (its value does not depend on the size of the system) and not an extensive one (here). Climates must be considered on a regional, not global, scale, as must ecosystems. We must also consider the distribution of temperatures, which are biased by their geographical distribution (including oceans, which are under-represented in measurements) and by the urban heat island effect (incorporation of rural measurement stations into cities because of urban extension) (McKitrick, 2010). Numerous biases are associated with these very unevenly distributed measuring stations (SCE, 2019).
An unproven theory
So why has science gone so far astray? Because the global warming theory propagated by the IPCC is based on a physic-chemical theory that has never been verified experimentally, and has been called into question by competent scientists, including Nobel Prize winners such as John Clauser, who won the physics prize last year (Clauser, 2023).
This is the radiative greenhouse effect, an effect that has never been demonstrated, as the Earth is not a greenhouse (SCE, 2020 ; Gerlich and Tscheuschner, 2009). The IPCC was created in 1988 by two organizations, UNEP (United Nations Environment Program) and WMO (World Meteorological Organization). Its main objective was to ‘assess … the risks associated with anthropogenic climate change‘. It immediately attributes the entire rate of CO2 increase since 1958 to an anthropogenic cause. The contribution of anthropogenic CO2 in the atmosphere is just under 5%, and the IPCC acknowledges this. Natural processes are therefore not taken into consideration when discussing global warming. This assertion of principle means that all the models developed by the IPCC always predict atmospheric overheating, and never agree with in situ observations (Blamet, 2022 ; Scafetta, 2023a). Apocalyptic predictions that have never been verified (Arctic melt expected in 2013, etc.) demonstrate the unreliability of these models (Scafetta, 2023b). The IPCC has reached a dead end in this way, ignoring natural processes and paleoclimatic data, but this does not prevent it from propagating alarmism that is becoming more urgent by the day, under pressure from economic and industrial interests.
Climate, a long story
So, if it’s not mankind, what are the natural processes involved in climate change? They are numerous and interfere in amplitude and frequency, making their respective roles very difficult to establish. For this reason, there’s no point in rushing into things, and it’s important to bear in mind that climatology is a young and complex science. It took over 50 years to validate the theory of plate tectonics, which was equally complex, did not foster fear, did not attract money, and did not occupy the media and many politicians daily.
Natural cycles operate over highly variable timescales, well beyond the successive 30-year segments (1930-1960, 1960-1990, etc.) that the WMO (WMO, 2021) considers to be the reference period for characterizing the Earth’s climate! Geology (paleontology, sea level ….) and climatology (including astronomy) are characterized by overlapping cycles of several hundreds and thousands of years. Most of these cycles (of which there are at least twenty) are not yet fully understood and include evidence of temporal instability (chaos). They are linked to oceanography, the Sun, the Planets, gravity, volcanism, plate tectonics and so on.
They are all the utmost importance, especially those linked to the thermohaline circulation ignored by the IPCC. The main ones are (Nebert, 2023) : (i) Milankovitch cycles or astronomical forcing cycles (position of giant planets in relation to the Sun, solar magnetic field, cosmic rays influencing clouds, etc.), with approximate periods of 26,000 years, 41,000 years and 100,000 years accounting for the observed ice ages, see here; (ii) Bond cycles or lunar tidal cycles of around 1,500 years responsible for warming and cooling peaks every ~750 years; (iii) Atlantic multidecadal oscillations ~50-70 years, (iv) Pacific decadal oscillations ~30-40 years; (iv) Hale cycles (sunspot activity) ~5-10 years (Savitzki, 2023 ; Zharkova et al. 2023); (v) El Nino/La Nina oscillations, ~2-7 years and ~12-18 months respectively; (vi) little-understood quasi-biennial oscillations (~30 months) (linked in part to alignments of the Sun, Jupiter, Saturn and Venus); (vii) North African climatic cycles ~19000 and ~23000 years linked to gravity and changes in the orientation of the Earth’s axis (precession); (viii) submarine and aerial volcanic eruptions, of random frequency and duration, and so on. (Harris, 2023). The alignment of the planets is also at the origin of a ‘Milankovitch-type’ cyclicity, but of short duration, capable of explaining the periodicity of many of our Planet’s natural phenomena (see Courtillot et al., 2023) for a complete bibliography).
Many other factors influence climate
In addition to these ‘global’ processes, there are a series of ‘regional’ processes, such as (a) changes in cloud cover (Blaisdell, 2023); (b) the extent of vegetation cover (Moreno-de las Heras and Nicolau, 2008); (c) aerosols, dust and organic molecules in the atmosphere (WMO, 2021 ; Haywood, 2016); (d) the urbanization of cities (Ceres, 2023), and so on.
The variety of natural processes affecting the climate is very great, and these processes do not act in a linear way but are most often the result of a chaotic evolution of the climate in the mathematical sense of the term (SCE, 2019). The processes interact, with positive or negative feedbacks at different times, and overlap at all possible scales, sometimes even acting synchronously: astronomical forcing (Jupiter, Saturn, Uranus, Neptune) induces a gravitational effect on the heliosphere, causing specific oscillations of longer solar cycles (Bray-Hallsatt cycles, ~2100-2500 years; Eddy ~ 800-1200 years; Suess-de Vries, ~ 200-250 years; Jose,~155-185 years, Gleissberg, ~80-100 years, etc ).
Extreme events are also a constant in the geological record and historical markers of the Planet. Contrary to what is reported by the media, they are not currently on the increase (see Budyn’s SCE articles, including one of the most recent SCE, 2023, see also Alexander, 2023) and the IPCC formally acknowledges this in its recent reports.
Calm and respect, if we want to make progress
What can we conclude when faced with an analysis of global warming diametrically opposed to that of the IPCC, considered by the media and politicians to be the « official science« ? Are all the scientists who counter-argue the official thesis – almost all of whom are top-flight scientists, including Nobel laureates and other scientific prize-winners – notoriously incompetent, ideologues, dishonest fame-seekers, or corrupt sell-outs to various industries (especially the oil industry)? It’s easy to ostracize them with the help of the media, especially when their arguments don’t have the same media impact, due to a lack of reasonable debate, or even debate at all. On one side are the IPCC-affiliated scientists who hold the truth, on the other are those who are considered incompetent (including Nobel Prize winners!). Yet almost everyone in both ‘camps’ is an established academic. The latter, the « skeptics », are well-versed in the peer review system, and the « scientific approach » sensu stricto is no stranger to them, most of them being reviewers for numerous journals and/or authors of recognized articles.
Critical thinking and common-sense show that climatology is still in its infancy, a young and highly complex science. Going too fast is bound to lead us down the wrong road, and acknowledging this afterwards seems impossible given the financial stakes involved and the problems of (scientific) reputation to be defended against all odds. Alarmism still has a long way to go, driven by the media and politicians, almost always non-scientific and almost always keen on ‘scoops’. Already today, this climate emergency has made young people (well-trained from elementary school) eco-anxious. We’re at the antipodes of what happened with the theory of plate tectonics, since Wegener, an astronomer-meteorologist, in the 1910s-1920s, also criticized at every turn; it took just over 50 years to validate this theory thanks to paleomagnetism revealing the expansion of the ocean floor along passive ripples. In the end, it was paleomagnetic, geologists and physicists who validated this theory, demonstrating, if proof were needed, the plurality and complementarity of research fields in solving even the most complex scientific problem. Even today, plate tectonics is supported by many disciplines, without everyone being a geologist.
Yes, the IPCC has decreed that natural phenomena have no place in the discussion, and that man alone is responsible for climate change (whose very wording has often changed, too (cf. climate disruption, global warming) through his action on the ‘CO2 button’. Let’s get back to basics, and listen to those who have good questions, which unfortunately are most often only answered by dismissal (a fine example here with Alimonti et al. 2023) or ad hominem attacks.
In view of the current uncertainties concerning the data linked to natural processes, including the carbon cycle, it is time to abandon the equation ‘CO2 increase = warming’ (Wrightstone, 2023). There are many other ways to understand the climate, but it will take time, given the complexity of the phenomena and a scientific approach that does not always speak its name (SCE, 2023).