Earth operates a network of molten upwellings from deep seams in the planet's crust which act to shove tectonic plates across the seafloors where these plates bump into continental land outcroppings. There the spreading plates subduct beneath the continental rims and simultaneously thrust mountains upward from sea level. Such crustal movements continue to alter our global topography today. Atmospheric composition is largely unaffected by these tectonic movements except during volcanic eruptions which emit gasses that are subsequently diffused about the globe by wind action.
Space operates a system of radiant inputs to the earth: both continuous cosmic rays from deep space and variable solar rays from our nearby sun. From time to time the sun produces solar winds having magnetic effects that perturb the incoming cosmic rays causing them to vary in intensity. The primary solar rays vary also but to a lesser extent than the solar-perturbed cosmic rays. Atmospheric composition is largely unaffected by these radiant inputs but one component of the atmosphere undergoes reversible change-of-state to an extent that is dependent on the intensity of the incoming cosmic rays. This component is water.
Water evaporates from the earth's surface as a clear vapor. Each water vapor molecule has a diameter of 1.5 angstroms. Incoming solar radiation contains wavelengths ranging from 1000 angstroms to 10,000,000 angstroms. Much of this incoming solar radiation passes over and through the clear water vapor, warming it in transit and continuing downward to the earth where it proceeds to warm the planet's surface. The cosmic rays, erratically constrained by the solar winds, convert some portion of the clear water vapor to liquid droplets ranging in size from 20,000 to 400,000 angstroms. Incoming solar radiation cannot pass readily through these large droplets and instead is scattered and partially redirected back into space. So incoming solar radiation can be either absorbed and transmitted (as with clear water vapor) or scattered and reflected (as with cloud droplets.) When the sun permits the cosmic rays to do their job of forming clouds then the planet will be cooled. When the solar winds withhold enough of the cosmic rays to restrain cloud formation then the planet will be warmed.
Down at the earth's surface water mediates life's processes. In watered terrestrial regions gaseous carbon feeds photosynthesis-powered carbon chain growth as life converts CO2 into solid carbonaceous plant matter, with some reoxidized to CO2 and some buried. In coastal shallows life additionally converts CO2 into the solid CaCO3 component of animal matter, with some redissolved and dissociated and some buried. These active life zones act as CO2 sinks, depleting the local atmospheric CO2 concentrations, and drawing additional CO2 from the diminishing reserves elsewhere in the atmosphere.
The accumulated solidified carbon products are then transported by tectonic movements and are either pushed upward into mountainous formations or dragged downward beneath the surface to be heated and pressure-cooked into pockets of fossil fuels. In either case the life-formed carbon-rich solid matter is carried away from the wet biologically active zones into locations where life processes are arrested and the carbon is forcibly sequestered.
Over time the earth has seen gaseous CO2 levels fall from the original 0.80% to our current 0.04%. Photosynthesis has been busily productive but the relentless tectonic conveyances have carried away and stored life's solidified carbon-containing products, leaving them in limitedly accessible locations awaiting mankind's efforts to disinter some fraction of these vast stores to use as fossil fuels and thus to regenerate CO2. The assertion that neither the mammoth tectonic mechanism nor the immense space radiant mechanism is overawed by either life's maladaptive CO2 burials or by mankind's trifling energy use is surely one of the greater understatements of all time. These primordial earth/space processes acted to warm and to cool the planet and to rearrange its surface features long before life began and they will continue to perform their accustomed activities long after life completes its self-extinguishing sojourn.
Since controversies abound in this matter you may consult: Goethe Universitat-Cloud ITN; Journal of Geophysical Research-Vol.110-Nir J Shariv; and the CERN Cloud Project. Expect to witness increasingly rational parsing of the relative importance of all the change agents intrinsic to this geophysical system. But however continuing research evolves we can already confidently state that the baseless claims of the CO2 is a pollutant crowd are insupportable on their face in light of the indisputable evidence of life having flourished throughout a 95% decline in atmospheric CO2 concentrations as documented in the scientific record. Disaffected humans will just have to find something else with which to flagellate themselves and their betters. We can take comfort however in the knowledge that their need is great, their determination unabashed and their perverse imaginations sufficient to the task.
James R. Fencil is the technical director of a Midwestern corporation, and an alumni scholar at the U. of C. Graham School in Chicago.