Is the temperature of Venus determined more by atmosphere composition or pressure?
Its an important question to ask because Venus is often cited as an example of the hypothetical "runaway greenhouse effect" by the climate change movement.
There are a number of problems with this assumption. Firstly it works by assuming that Venus and Earth are sister planets that have been orbiting the sun for a similar length of time. There are a number of theories which better account for why Venus has anomalies with its magnetic field, orbit and unusual dense atmosphere. The atmosphere density is only unusual if we work on the assumption its been in orbit for billions of years. If, like is credibly put forward, Venus was a recent arrival, possibly in the form of a giant comet, ejection from our star or elsewhere or knocked from a gas giant during a period of Orbital Chaos.
Planets lose their atmosphere over time, Venus has an impossibly thick atmosphere. A widespread cloud layer is put forward as enough to reflect enough sunlight and actually cause a moon year long snowball earth, yet we are told that for Venus it's not reflecting incoming light and heat. That goes without saying because the conventional view is that no heat would be produced sustainably it's assumed it's only retained. Other options cater for those circumstances without needing assumptions or intractible conflicts. My informal speculation was just puff for context. It does help make the conventional take seem a little less certain though.
For those that are interested only in atmosphere composition, solar proximity, greenhouse claims and atmospheric pressure, see the clip below and links. Otherwise my conclusion doesn't factor any of the puff in and can be found just below the clip and links.
https://www.space.com/19537-venus-comet-atmosphere.html
https://www.esa.int/Science_Exploration/Space_Science/When_a_planet_behaves_like_a_comet
https://www.scientificamerican.com/article/solar-wind-transforms-venus-into-shape-of-comet/
There has been more credence added to this sort of thinking recently when the Parker Solar Probe picked up that Venus ionosphere changes with the suns 11 year cycle (below embedded clip)
If you want a little history, the sordid story of how Venus data has been politicized, since even before the climate change movement got into gear, can be found HERE (courtesy Ted Holden.)
But rather than speculate let's consider the facts. Key indicators.
- Venus has nearly 100 times MORE pressure than Earth and its atmosphere is 96% CO2 by composition.
- Mars has over 100 times LESS pressure than Earth and its atmosphere is 95% CO2 by composition.
- Mars actually has a greater overall density of CO2 molecules than earth does despite its thin atmosphere on account of its 95% composition compared to earths trace levels compared to history, a paltry 0.04% (not a typo, we have 15 times less CO2 now than we did when life first really kicked off on this planet during the Cambrian Explosion.*
So is the temperature of Venus determined more by atmosphere composition or pressure?
One of those is affecting temperature a lot more than proximity to the sun.
Earth has only 0.04% CO2 and is midway between the two in solar proximity and temperature extremes.
It is also midway in atmospheric pressure but its CO2 levels are insignificant compared to the other two planets.
It follows logically:
(If a choice were insisted on)
That atmospheric pressure, not composition is the primary determining factor in the extreme surface temperature of Venus. Other factors such as proximity to the sun are important, as are age. Using known empirical data and deductive reasoning by weighing variables against each other for the 2nd, 3rd and 4th planets there appears to be no correlation whatsoever between CO2 and surface temperature, and any other gas under pressure and close enough to the sun should out factor the CO2 composition factor by approx 1000:1 or more, as Venus and Mars seem to indicate.