Reasons to Doubt the Anthropogenic and CO₂ Origins of Climate Change

• During the last 400,000 years, changes in the temperature of the atmosphere almost always precede changes in the content of CO₂ by 600–6000 years. To use a corrected legalistic Latin phrase Ante hoc ergo non propter hoc — Before the thing, therefore not caused by the thing.
  

  Vostok ice core records for carbon dioxide concentration and temperature change

  See Eric Monnin et al, Atmospheric CO₂ Concentrations over the Last Glacial Termination Science 291, 112 (2001) and https://courses.seas.harvard.edu/climate/eli/Courses/global-change-debates/Sources/Temperature-leads-CO2-in-ice-cores/more/Monnin-2001.pdf

  During the last 600 million years, temperature and CO₂ have been essentially unrelated.

  

  Dr. C. R. Scotese, Analysis of the Temperature Oscillations in Geological Eras (2002)
  W. F. Reddman, Earth's Climate: Past and Future W. H. Freeman and Sons (2001)
  Mark Pagini et al, Marked Decline in Atmospheric Carbon Dioxide Concentrations During the Paleocene, Science 309, 5734, pp 600-603 (22 July 2005) [Ordovician period corrected 7 July 2008]
  Robert A. Berner, Reconstructed Atmospheric Carbon Dioxide Concentrations (2001)

  
  C. R. Scotese, H. Song, B. J. W. Mills, and D. G. Van der Meer, Phanerozoic paleotemperatures: The Earth's changing climate during the last 540 million years, Earth-Science Reviews 215, 103503 (2021) https://doi.org/10.1016/j.earscirev.2021.103503 and Global Mean Surface Temperatures for 100 Phanerozoic Time Intervals

  More complete discussion at Professors Challenge the Canard of Anthropogenic Climate Change

• The Sun has several activity cycles. Two of these resonate with a periodicity of about 1,500 ± 70 years. The Earth's temperature responds to these cycles, leaving a record in ice cores, stalactites, lake bed and ocean bottom sediments, tree rings, bogs, …, everywhere throughout the world. This is not a Northern Hemisphere Phenomenon as some claim.

  These cycles are also evident in the historical record, going back to the pre-Roman Egyptian cooling, the Roman warning, the Dark Ages, the Medieval warming, and the Little Ice Age, from which we are just now emerging. People didn't write “gee, the climate is cooling” (or warming) but Egyptians wrote about needing to build dams and canals, Romans noted that grapes were growing in Britain, Slavs moving up the Eastern Alps thought the Germans had abandoned the land because they got fat and lazy — and then they had to abandon the same land when the glaciers returned, ….

  The cycles appeared in the 1995 IPCC report, but were removed in the 2001 report, at the insistence of the editor, Michael Mann, to preserve the illusion of reality of his infamous “Hockey Stick” graph.

  
  The last 1000 years of Earth Temperatures from Tree Rings, Ice Cores, and Thermometers
  Figure 22 in IPCC's Climate Change 1995

  
  Infamous “Hockey Stick” Graph that Eliminates the Dark Ages, the Medieval Warming, and the Little Ice Age
  Figure 2.20 in IPCC's Climate Change 2001

  See Unstoppable Global Warming — Every 1500 Years by Siegfried Fred Singer and Dennis T. Avery, ISBN-13: 978-0-7425-5116-9.

• Analysis of ice cores by the Greenland Ice Project (GrIP) show that 1870 was the coldest year in Greenland in more than 8,000 years. 1870 was also about the time that widespread accurate temperature records began to be kept. If you begin measuring at the minimum, all you record is increase.
  

  From https://www.iceandclimate.nbi.ku.dk/data/ddjtemp.txt:

  In Greenland:
  The warmth of the climatic optimum during the European stone age 5000 years ago is clearly seen, just as the cool period during the Roman age and the relative warmth of the Viking age (where the Norsemen settled in Iceland and Greenland) and the two cold periods of the "little ice age" at 1600 AD and 1875 AD. The warming in Greenland in the 20th century only lasts until 1950 AD. After that it has become colder.

• Carbon-14 is created in the upper atmosphere by cosmic rays. It is radioactive with a half life of 5,730 years. That means half of a given quantity of it will have decayed after 5,730 years, half of what's left after another 5,730 years, …. After ten half lives, less than 0.1% of the original remains.

  Fossil fuels have been underground, not exposed to cosmic rays, for millions of years. They therefore do not contain any carbon-14: Burning fossil fuels dilutes the atmospheric concentration of carbon 14 in CO₂.

  If emissions of CO₂ caused by burning fossil fuels were the only source for the observed decrease in the concentration of carbon-14 in CO₂ in the atmoshphere since 1750, and therefore the only source of increase of the total concentration of CO₂ in the atmosphere, the trend of its dilution, as measured in stalactites, ice cores, lake bed and ocean bottom sediments, bogs, …, would be much more than observed.

  Kenneth Skrable, George Chabot, and Clayton French analyzed this in World Atmospheric CO₂, Its ¹⁴C Specific Activity, Non-fossil Component, Anthropogenic Fossil Component, and Emissions (1750-2018), which appeared in Health Physics 122, 2, pp 291-305 (1 February 2022), doi: https://doi.org/10.1097/HP.0000000000001485. From the abstract:

  After 1750 and the onset of the industrial revolution, the anthropogenic fossil component and the non-fossil component in the total atmospheric CO₂ concentration, C(t), began to increase. Despite the lack of knowledge of these two components, claims that all or most of the increase in C(t) since 1800 has been due to the anthropogenic fossil component have continued since they began in 1960 with the "Keeling Curve: Increase in CO₂ from burning fossil fuel." Data and plots of annual anthropogenic fossil CO₂ emissions and concentrations, C(t), published by the Energy Information Administration, are expanded in this paper. Additions include annual mean values in 1750 through 2018 of the ¹⁴C specific activity, concentrations of the two components, and their changes from values in 1750. The specific activity of ¹⁴C in the atmosphere gets reduced by a dilution effect when fossil CO₂, which is devoid of ¹⁴C, enters the atmosphere. We have used the results of this effect to quantify the two components. All results covering the period from 1750 through 2018 are listed in a table and plotted in figures. These results negate claims that the increase in C(t) since 1800 has been dominated by the increase of the anthropogenic fossil component [my emphasis]. We determined that in 2018, atmospheric anthropogenic fossil CO₂ represented 23% of the total emissions since 1750 with the remaining 77% in the exchange reservoirs. Our results show that the percentage of the total CO₂ due to the use of fossil fuels from 1750 to 2018 increased from 0% in 1750 to 12% in 2018, much too low to be the cause of global warming.

• Ponder this graph. The area under each curve is Earth's radiated power. Reducing radiated power increases temperature. DOUBLING CO₂ would change the Earth's radiation budget by 1.08% (Are you actually able to see a difference between the red and black curves?).
  

  Each DOUBLING of CO₂ concentration ADDS 0.84 degrees Celsius to the average Earth surface temperature, not the 3 degrees the IPCC uses to scare us. Read that again: A DOUBLING, not an increment from 400 to 500 ppmv.

• In Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate, which appeared in Science (July 9, 1971) pp 138-141, S. I. Rasool and S. H. Schneider wrote on page 139

  From our calculation, a doubling of CO₂, produces a tropospheric [lower atmosphere] temperature change of 0.8°K. However, as more CO₂ is added to the atmosphere, the rate of temperature increase is proportionally less and less, and the increase eventually levels off. Even for an increase in CO₂ by a factor of 10, the temperature increase does not exceed 2.5°K.

  Therefore, the runaway greenhouse effect does not occur because the 15-μm CO₂ band, which is the main source of absorption, 'saturates,' and the addition of more CO₂ does not substantially increase the infrared opacity of the atmosphere.

  They wrote this at the time when "scientists" were worrying about the coming ice age. Their conclusion is "we can't prevent the ice age by burning fossil fuels."

  What does "saturate" mean? Imagine you have a greenhouse in which visible light passes through the glass roof, strikes materials inside and warms them. Then some of that heat is re-radiated as infrared light. Your greenhouse warms because the glass does not transmit infrared light as well as visible light. In other words, it holds heat inside. Suppose it retains 90% of the infrared light. If you add another sheet of glass, your greenhouse does not retain 180% of the re-radiated infrared light. That would be absurd. Instead, the second sheet reflects or absorbs 90% of the 10% that got through the first sheet. A third sheet would reflect or absorb 90% of the 1% that got through the first three sheets....

• Mark Twain said "Prediction is difficult. Especially about the future." Time-series computer models (dotted gray lines in the figure below) ought to be able to "predict" the past, which can be verified against measurements. 101 of 102 climate models utterly fail when started with 1975 data and then "predict" what happened during the last fifty years, especially after 1995. Whose model is that one outlier, that seems to get things right? The Russian model.
  

Read more at Professors Challenge the Canard of Anthropogenic Climate Change
Richard Lindzen, MIT Professor of Earth, Atmospheric and Planetary Sciences
William Happer, Princeton Professor of Physics