CO2 The Miracle Molecule
... CO2, possibly above all other molecules, is responsible for supporting all life on
earth. It is the feedstock upon which all plant life depends, in order to produce the complex organic molecules necessary for growth, by means of photosynthesis. Without atmospheric CO2 there could be no plant life and consequently no animal life either. Planet Earth would be dead !
The Greenhouse Effect
Without atmosphere the world be a very cold inhospitable place. The heat from the sun absorbed by the earth would be re-radiated into space at a rate dependent solely on the earth’s temperature.
... how could a concentration of CO2 molecules, represented by 4 molecules in every 10,000, be such a driver of climate catastrophe. The answer is because it is a greenhouse gas.
Only two of the five major atmospheric constituents are classified as greenhouse gases, H2O and CO2. These gases have the ability to absorb the outgoing infrared radiation from the earth, and act to reduce the amount of re-radiation into space, thus increasing the earth’s temperature. The other gases, nitrogen, oxygen and argon are totally transparent to this radiation and have no impact upon temperature.
70% of the energy radiated from the earth is removed by a mixture of 0.1% H2O and 200ppm of CO2. This alone is sufficient to raise global temperatures from the chilly 255K of the estimated zero atmosphere condition to 284.3K, less than 4deg below current average temperatures.
... Further increases in both H2O and CO2 have relatively small impacts on temperatures. This is due simply to the fact that at current concentrations the spectra of both H2O and CO2 have effectively extracted most of the energy at wavebands corresponding to the infrared molecular absorption spectra. There is little further energy to be extracted by adding more H2O and CO2.
... The possibility of positive feedback from water vapour is discounted by the simple fact that the H2O spectrum is incapable of absorbing significant further amounts of radiated energy and the modest increase in temperature due to increasing CO2 levels is unable to deliver any significant increase in H2O concentration due to the specific relationship of H2O saturation vapour pressure and temperature.
It would take an increase in temperature of 10deg C. to double the mean H2O atmospheric concentration, and that doubling would only result in a temperature increase of +2deg C.
... The “greenhouse effect” is dominated by the absorption spectrum of H2O, with a little help from CO2. At current concentrations of both gases it is inconceivable that further increases in
concentrations will lead to any significant warming.
In short, there is no climate emergency, at least due to greenhouse gases."