Earth’s average temperature is a balance between heat radiated in from the sun, out from Earth, and generated internally.
Almost one-third of the sun’s radiation reaching Earth is reflected. Excluding internal heat generation and greenhouse gases, Earth’s distance from the sun and that reflection, would give it an expected average global temperature of about – 17˚C. Greenhouse gases, mainly carbon dioxide, CO2, and water vapour, H2O, raise Earth’s temperature by 31˚C. Earth’s average temperature of 14˚C makes it a habitable planet for large life forms.
Most of the radiation from the sun arrives as visible light. When absorbed it warms the planet to the stage where it emits infra-red radiation. Greenhouse gas molecules in the atmosphere are mainly water vapour, H2O, carbon dioxide, CO2, ozone, O3, and methane, CH4. Each captures the radiation it can, causing the molecules to vibrate. They contact air molecules and pass some of their energy across to those molecules, warming the atmosphere.
Greenhouse gas molecules also radiate heat. When radiated down, it warms the air below. Heat radiated up continues to warm the air above it. Eventually there are no longer enough molecules above to capture the heat. It is radiated out into space
The amount of warming each type of molecule contributes to the atmosphere is the difference between the energy absorbed at Earth’s surface and the energy that is radiated into space. The balance between the two determines how much heat is captured in the atmosphere. Averaged globally between the equator and poles, and land and sea, that gives a 31˚C temperature rise.
H2O is responsible for almost three-quarters of that rise. CO2 contributes 8 – 9˚C to average global temperature. The CH4 concentration is so low that its effect is not positively detected above the noise associated with water vapour, which overlaps it absorption. O3 is generated in the upper atmosphere and radiates a little heat down to the surface.
It is the CO2 contribution that is of greatest interest. The website shows how some climate change scientists model temperature change with increasing atmospheric CO2. They use a model in which radiation absorption by CO2 molecules is not saturated. It suggests some of the radiation that CO2 molecules can absorb can travel right through the atmosphere and escape directly from Earth’s surface to space. When there is more CO2 in the atmosphere, more of the radiation will be captured and further warm the planet.
The 1950s data showed that 0.03 per cent atmospheric CO2 warmed the planet by 9˚C. Based on that and unsaturated absorption, an additional 0.01 per cent would warm the planet by another 3˚C. Vostok ice core samples showed that a change of 0.01 per cent atmospheric CO2 was associated with a 10˚C change in temperature. It was called anthropogenic global warming (AGW). Both warming factors are sufficiently high that urgent action was requested to prevent that runaway greenhouse effect producing a Venus-like scenario. It didn’t happen. AGW was replaced by climate change, CC. Figures close to those warming factors are implied in climate change models.
CO2, air, and H2O molecules typically have a diameter of about 0.3 nm (3 x 10–10 m). A CO2 concentration of 0.03 per cent means every molecule on Earth’s surface has about ten million (107) CO2 molecules directly above it. CO2 is a powerful greenhouse gas. There is no way that any radiation that CO2 can absorb will pass 100 CO2 molecules, let alone 10 million. For the CO2 concentrations, all radiation its molecules can absorb occurs within the couple of metres.
Some of the absorbed heat is radiated down, keeping the planet warmer. Some of it is radiated up. The amount of infra-red radiation emitted from Earth depends upon the temperature at the altitude at which the emitted radiation has so few molecules above it that it goes into space. Until that occurs, CO2 radiation absorption is saturated for its concentration.
CO2 molecules at an altitude in which the temperature is about – 60˚C radiate directly into space because there are not sufficient molecules above to absorb its radiation, Water vapour freezes near 0˚C. Much of the radiation it emits is at and a little lower than 0˚C. Not much goes higher into the colder atmosphere. The displayed University Center for Atmospheric Research, Boulder, Co, saturation mechanism, and any variation of it that suggests saturation is not complete, does not apply. That is a major error source.
That does not mean that increased atmospheric CO2 does not warm the planet. CO2 has a property that the greater its concentration, the wider is the wavelength range it can absorb. As the atmospheric CO2 concentration increases, the average global temperature will rise. The effect is logarithmic. A small increase, 0.03 per cent to 0.04 per cent, may be noticed. Further increases will have a smaller impact on temperature.
In the 19th century, CO2 was known to be a strong greenhouse gas. Some believed its warming effect was already saturated. Improved analytical instruments showed absorption increased with concentration. Even though that increase was logarithmic, a prominent scientist commented, ‘… that CO2 is nowhere near being saturated.’ It is possible comments like that justified the continued use of the UCAR presented simplicity.
The mechanism climate change scientists use to model temperature increase due to atmospheric CO2 increase, is hidden deep within their models. They have created a ‘doomsday’ scenario based upon their modelling and words like, ‘We are the experts. We know what we are doing. If you do not do as we tell you, civilization will soon be destroyed.’ Some suggested it could come as early as 2030.
With no other explanation and huge government funding, climate change experts have caused huge psychological damage to children, large power cost increases that make life more expensive, considerable social disruption from extinction rebellion and other protesters, hundreds of deaths when renewable energy sources failed, and more. All that, and they won’t explain the science upon which their predictions are based. Nor do they have enough expertise to realize the total production of solar and wind generators, along with storage batteries, generate more atmospheric CO2 than the same tasks performed using fossil fuels.
In summary, additional atmospheric CO2 does increase average global temperature. But not by very much and not in any manner that could cause a runaway warming effect! Those who wish to disagree should do so by explaining the science upon which their ideas or opinions are based.
It is time for climate scientists to give a descriptive summary of the different scientific factors used, and the weighting given to them, in their models that lead to their conclusions. Spectator Australia readers and members of the general public would like to know what they are. Their often quoted comment ‘that more CO2 gives more warming’, and ‘that is what our models predict’ are not acceptable.
Got something to add? Join the discussion and comment below.