How does CO2's GreenhouseEffect ccome about?
A first thing to understand is that the Greenhouse effect occurs, to a human observer, instantaneously. The heat (as a photon flux - see the page “The Greenhouse Effect”) leaves the surface of the Earth and, if unimpeded it reaches an observing satellite in about 0.0003 seconds. Photons experiencing many absorption, and subsequent emission, events will still reach an observing satellite in less than 0.01 seconds.
This near instantaneous process goes on all over the Earth, so the instantaneous Greenhouse varies hugely from place to place and second to second.
Human observers, to make sense of it, must average this near-instantaneous effect. Averages are most commonly reported on a monthly average basis, sometimes combined into annualised averages.
Most temperatures are reported as anomalous values against the average for that particular month for a ‘base period’. For example the satellite temperatures maintained by Huntsville Alabama (Dr Roy Spencer) are against the 1991-2020 averages.
The monthly average total Greenhouse effect may be estimated (see page “The Cardinal Model”) and has high seasonality (maximum in Northern Hemisphere summer).
This illustrates the high degree of variability of the total Greenhouse effect.
This variability is even more marked when considering diurnal swings, average daily or specific regional swings.
The Cardinal Model splits this highly varying monthly average total global pattern into contributions due to water, CO2 and others. It does this with a very high level of fit between modelled and observed – a nearly perfect fit.
The CO2 contribution comprises about 21% of the total.
Most of the variability comes from the effects of temperatures (specifically Earth’s surface temperature and that of the mid-Troposphere and the lower Stratosphere.
The Cardinal model assesses that only a minimal contribution comes from the increased concentration of CO2 since pre-industrial times. To 2025 this is about 0.34 (+/- 0.03) WM-2. In temperature terms this is about 0.07⁰C.
