As CO2 increases in the atmosphere, its warming power diminishes over time to near-zero. This simple physics is ignored by the climate alarmist community
By Roger Palmer, guest post on Andrew Roman blog, Oct. 11, 2024
As the sun heats the earth’s surface, the earth radiates infrared energy back into space. The earth slowly heats up until the amount of infrared energy it radiates into space equals the amount of solar energy absorbed by the earth’s surface.
If the earth had no atmosphere, this “equilibrium temperature” would average about minus-13°C – too cold for comfort! But the earth’s atmosphere raises the equilibrium temperature to an average of about +15 degrees C, making earth habitable. Let’s look at how the atmosphere affects the earth’s average temperature.
The atmosphere consists of air (a mixture of gases), and small amounts of particulate matter. Air is primarily composed of nitrogen and oxygen, plus smaller amounts of several other gases, the relevant ones for this discussion being:
- Water Vapour – 0.001% to 5%, or 10 to 50,000 ppm (parts per million); this gas does most of the warming.
- Carbon Dioxide – currently 0.042% or 422 ppm, but gets most of the attention.
To understand the “Greenhouse Effect” and the role of carbon dioxide (CO2) in it, we need to focus on the infrared energy radiated upward from the earth’s surface as it warms. This energy is heading for space, but some of it will meet greenhouse-gas molecules in the atmosphere.
This energy will be absorbed by the molecules and re-radiated in all directions, including back down towards the earth’s surface. This re-radiated energy will have a warming effect. Of course, the energy from the sun also passes through the atmosphere toward the earth’s surface, but this energy is at much shorter wavelengths, and therefore the greenhouse gas molecules do not interact with it. What makes a gas a “greenhouse gas” (GHG) is that it absorbs infrared wavelengths but not visible wavelengths.
more GHG molecules means less warming, not more
This explanation suggests that the warming effect of GHGs will be greater if there are more gas molecules in the outgoing energy path, thereby causing more warming. And they do, up to a point. But this is not a purely linear relationship.
As the gas molecules get packed in together, there is less opportunity for a concentration increase to result in additional molecular interactions. This relationship is logarithmic. This means that if the water vapour or CO2 concentration is low, a small increase in concentration will have a much bigger warming effect than the same increase when the concentration is higher.
This topic has received a great deal of study by learned physicists and climatologists, and many papers have been published which confirm the logarithmic relationship. The figure below illustrates this. Looking just at CO2, at higher concentrations, the reduction in sensitivity causes a “flattening of the curve”, and the greenhouse effect is said to be nearing “saturation”.
A simple analogy is to imagine that you have a black wall that you want to paint white. The first coat of white paint has a major effect on the perceived colour, but the black still shows through. The second coat makes it whiter, but you can still see some faint blackness. After 5 or 6 coats, the wall looks white, and additional coats will not change its appearance. The paint coatings are then “saturated”.
CO2 levels are near ‘saturation’
At the current CO2 concentration of approximately 422 ppm, its concentration is on the flatter part of the curve. Further increases in CO2 emissions beyond this point will have minimal effect on the earth’s temperature.
This simplified description just discusses the basic concepts of greenhouse gas physics. However, the earth’s climate and surface temperature also depend on many other powerful factors, such as:
- variations in the Sun’s luminosity and spectral distribution
- variations in cosmic rays
- variations in the Earth’s magnetic field
- variations in cloud cover
- variations in the Tropopause Inversion Layer
- the amount of heat stored in, released from, or transported by the oceans and their currents
- cyclical local changes in ocean currents (El Nino, La Nina, AMO, etc.)
- several feedback mechanisms (both positive and negative)
- volcanic eruptions. (On January 15, 2022, the Hunga Tonga submerged eruption increased atmospheric water vapour, the major greenhouse gas, by approximately 10%; this eruption, not CO2, is a major source of the current “global warming”)
- long-term variations in the orbital parameters of the earth and the planets (leading to Milankovitch cycles)
In other words, changes in atmospheric CO2 concentrations are not the major factor in changes to the earth’s climate, and CO2’s incremental effect is becoming vastly reduced (i.e., near “saturation”) as its levels increase.
Canada’s climate policies need to recognize that efforts to slow the rate of global warming by reducing Canada’s CO2 emissions are futile, and our limited financial resources need to be devoted to areas where they will do the most good.
This article originally appeared on lawyer Andrew Roman’s blog and has been slightly edited. Roger Palmer is a retired electrical engineer and technological consultant. To read the original article, click here.