So here’s a fun little article by a guy named Harry Dale Huffman that (nearly) disproves the central hypothesis behind the extreme heat of Venus.
Recall from your basic astronomy training that Venus is supposed to be as warm as it is because its’ atmosphere is mostly composed of greenhouse gases which absorb outgoing infrared radiation from the sun and allow visible light to pass. Early in the planet’s history, the theory goes, it was not remarkably warmer than Earth since it possessed a thinner atmosphere, but after millions of years with a runaway greenhouse effect, the mass of its’ oceans boiled away along with anything else that might evaporate in the heat, thus thickening its’ atmosphere to the point where it exerted unbearable pressure on the surface and causing the planetary temperature to skyrocket.
There’s just one little problem. Venus, with its 96% CO2 and 4% water vapor (essentially) atmosphere, is currently opaque to visible light (only the thinnest veil of dim red light reaches the surface)…in fact at pressures around 1 atmosphere, the percentage of visible light relative to the top of the Venusian atmosphere drops to less than 0.1%. If there were a greenhouse effect that was substantially different than the effect observed on Earth, we would see it in the temperature data in that uppermost 1 atm of mass. We don’t. The Venusian temperature profile is, in fact, remarkable similar to Earth’s temperature profile down to the 1 atm. level. If you applied an atmospheric pressure as impressive as that which exists on Venus to the Earth, we would boil almost as hotly as that planet does.
That doesn’t mean, as Huffman claims, that there is NO greenhouse effect on Venus or on Earth. But it DOES mean that the existing greenhouse effect is NOT related to the amount of CO2 in the air. How can it be? If it were, Venus would have a greater greenhouse effect than Earth does…we don’t see evidence of that in the actual data. 96% CO2 and at least as much H2O(g) on Venus and only 0.04% CO2 on Earth…and no difference in the greenhouse effect? Really?
Something is rotten here.