If humans never existed then the global average atmospheric CO2 concentration would be the same as it is today. The total amount of CO2 in the atmosphere is independent of source of the CO2 and primarily dependent on ocean surface temperature. The amounts of CO2 in both air and ocean are determined by a ratio in Henry’s Gas Law, which is dependent on water temperature as well as underlying ocean chemistry and physics. Human produced CO2 has no effect on the Henry’s Law ratio.
This does not imply that the atmosphere is free of anthropogenic CO2. CO2 from all sources is heavily mixed in air and ocean. Two giant fluxes of CO2 over 90 gigatonnes each (see graphic), absorption of CO2 into ocean water surface and emission of CO2 from ocean surface water, each flux 10 times larger than human CO2 emission, are mixed with human fossil fuel emission. Estimates of human CO2 emission are from about 5 to about 8 gigatonnes per year. These fluxes are mixed annually with CO2 sinks of about 750 gigatonnes CO2 in the atmosphere and 1020 gigatonnes of CO2 in ocean surface. (see graphic below)
All CO2 emissions from all sources are continuously and chaotically mixed in air and ocean. Ocean is about 98% of the hydrosphere, which includes all of the water on earth. Ocean is about 70% of the surface of the earth. The graphic below which is supported by the UN IPCC estimates that 1020 gigatonnes of CO2 are in the surface of the ocean. Each year about 8 gigatonnes of fossil fuel CO2 is mixed with 750 gigatonnes of atmospheric CO2 which is simultaneously mixing via two estimated 90 gigatonne fluxes with 1020 gigatonnes of CO2 in the surface of the ocean. The surface area of the ocean and its temperature controls atmospheric CO2 flux. CO2 flux is the amount of CO2 flowing through a surface in a period of time. Cold water absorbs CO2. Warm water emits CO2. The concentration of CO2 gas in air versus the concentration of CO2 gas in ocean surface is controlled by Henry’s Gas Law, which is not affected by the source of the CO2.
The addition to the atmosphere of CO2 from burning fossil fuels does not change the total amounts of CO2 in the atmosphere or in the ocean. Excess CO2 precipitates as solid carbonate and becomes stone in cold, alkaline ocean, for example limestone accumulates on the walls and continental shelves of ocean.
Human-produced CO2 is not responsible for global warming or cooling, or global greening, or glaciers melting, or polar bears, or social justice or any of the other claims either against it or favoring it.
“There is no climate emergency.” (William Happer and Richard Lindzen, National Review, 16 April 2021.) “Stop treating it [i.e. AGW…human-caused global warming/climate change] as a worthy opponent. Do not ascribe reasonableness to the other side. It is not reasonable, not true, not even plausible.” (Richard Lindzen, 31 March 2021. Zoom call Clintel Foundation)
The Carbon cycle. The figures indicate carbon storage and flows, expressed in gigatonnes One gigatonne is 1,000 million metric tonnes of carbon or 1 billion metric tonnes. A tonne is a metric unit equal to 1000 kilograms or 106 grams. A gigatonne is 109 grams. One metric tonne equals 1.102 tons. A ton is non-metric old English or American unit sometimes called a short ton. A ton is 2000 pounds. A tonne is about 10% more than a ton. The arrows are proportionate to the volume of carbon. The figures for the flows express amounts exchanged annually. Cartographer: GRID-Arendal. www.grida.no/resources/5390