Tyndall and his Greenhouse Effect

Tyndall's experimental setup to demonstrate global warming by CO2.

The three cornerstones of CO2 climate alarmism are Fourier, Tyndall and Arrhenius. In the previous post we inspected Fourier. We now turn to

• Tyndall (1861) On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction.—The Bakerian Lecture.

We read:

• But this aqueous vapour, which exercises such a destructive action on the obscure rays, is comparatively transparent to the rays of light. Hence the differential action, as regards the heat coming from the sun to the earth and that radiated from the earth into space, is vastly augmented by the aqueous vapour of the atmosphere.
• It is exceeedingly probable that the absorptionof the solar rays by the atmosphere, as established by M. Pouillet, is mainly due to the watery vapour contained in the air.
• De Saussure, Fourier, M. Pouillet, and Mr. Hopkins regard this interception of terrestrial rays as exercising the most important influence on climate.
• Now if, as the above experiments indicate, the chief influence be exercised by the aqueous vapour, every variation of this constituent must produce a change of climate.
• Similar remarks would apply to the carbonic acid diffused through the air, while an almost inappreciable admixture of any of the hydrocarbon vapours would produce great effects on the terrestrial rays and produce corresponding changes of climate.
• It is not, therefore, necessary to assume alterations in the density and height of the atmosphere to account for different amounts of heat being preserved to the earth at different times; a slight change in its variable constituents would suffice for this;
• Such changes in fact may have produced all the mutations of climate which the researches of geologists reveal.
• However this may be, the facts above cited remain; they constitute true causes, the extent alone of the operation remaining doubtful.

Tyndall reports on laboratory experiments on absorption, but presents no physical quantitative mathematical theory to support his claim that:

• an almost inappreciable admixture of any of the hydrocarbon vapours would produce great effects... on changes of climate.

Accordingly, Tyndall immediately withdraws the claim by stating:

• ...the extent alone of the operation remaining doubtful.

We find here the root of the contradictory arguments repeated over and over in CO2 climate alarmism: A small cause (change of CO2) can have a substantial effect on global temperature, but the size of the effect remains unknown.

The last repetition of Tyndall's argument appeared in Science on Oct 15: Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature by climate alarmist Gavin A. Schmidt et al.

But to show scientifically that a small cause will have a substantial effect requires a precise model so that the small cause can be distinguished from other small or big causes. In climate science this model is lacking, and therefore Tyndall's conjecture remains to be demonstrated.