While much has been made about CO2 causing warming “in theory,” the reality is just the opposite. The above chart demonstrates the rate of cooling of the atmosphere ( blue is the fastest cooling, dark gray is the fastest warming). CO2’s impact can be seen at the wavenumber 600 to 700/wavelength 13 to 18 microns.
Important Take Homes From this Chart:
- CO2 has basically no impact what so ever in the lower troposphere where all ground measurements and most glaciers are located.
- The condensation of water has the greatest impact on the temperature in the troposphere. As the altitude increases, more H2O precipitates out, releasing radiative latent heat.
- Heat travels through the atmosphere by conduction, convection, condensation and radiation. CO2’s and the greenhouse gas effect’s main mechanism is through radiation. Radiation travels at the speed of light.
- CO2’s only warming is identified in the tropopause. A location way above glaciers, Arctic Sea Ice and ground measurement instruments.
- If one envisions greenhouse gasses as nets that capture radiation and then release that radiation in all directions and the higher the altitude the bigger the holes in the nets, it becomes clear why an evenly distributed (400 ppm) greenhouse gas like CO2 would cause cooling. Radiation directed towards the earth is highly likely to be captured because the atmosphere is denser and have smaller holes (more CO2 molecules/m^2). Radiating back out towards outer-space, the holes become bigger (CO2 molecules are less abundant per m^2).
- To put it simply, the path of least resistance is for CO2 to radiate energy out of the atmosphere. Radiation easily passes through a thin atmosphere because there are few molecules to interrupt their path. In the graphic below, the red molecules are CO2, and it is easy to see how “radiative forcing,” is far more likely to sent radiation into outer-space than back to the earth. Because the atmosphere thins with altitude, the average path length of a radiated photon going up is longer than the path length of a photon going back towards earth. The photon takes 3 steps up, and 2 steps back, then 3 steps up, then 2 steps back. The physics of the atmosphere simply don’t favor CO2 trapping heat, they favor releasing it to outer-space.