williatw wrote:Let us see now…what is the ultimate known example of greenhouse gas warming via CO2? The planet Venus.
Venus is 67 million miles from the Sun; the Earth is 93 million. By the inverse square law: 932 /672 = 1.93. So Venus gets roughly twice the solar constant Earth gets. So I would expect it to be twice as hot. Venus surface temp averages about 900F; converted to Kelvin ((900-32)*5/9) = 482C+273.15 = 755K. Earth’s ave. temp is 287K. So Venus is 755/287 = 2.63 X hotter than earth. Or about 36% hotter than what you would expect from its closer distance to the Sun. But wait as we all know Venus has an atmosphere that is almost all CO2; and at 90atm pressure. Venus gravity at it surface is approx. 0.8 that of Earth’s; so 90/.8 = 112.5. So the mass of Venus’s atmosphere all CO2, a greenhouse gas, is approx. over a hundred times that of Earth’s; but only apparently adds about 36% higher temp over Earth’s than what you would expect just from its closer proximity to the Sun. Conclusion CO2 must be a relatively weak greenhouse gas. It would suggest we probably don't need to lose too much sleep worrying about the effect of the approx. 350ppm CO2 in our two orders of magnitude less massive total atmosphere. Also explains perhaps why my favorite Martian potential terraforming gas NF3 (Nitrogen Trifluoride) can be 17,000 times more powerful than CO2; it is because CO2 is obviously a wimpy greenhouse gas. Comments anyone?
That's not the whole story, if CO2 was the only thing involved then Venus wouldn't be nearly as hot as it is today. Sulfur dioxide is what's really causing the insanely high temps. In relatively small quantities that stuff isn't much threat but get enough of it together and it creates a blanket that doesn't allow anything out. If whatever caused all that SO2 hadn't of happened then Venus might of actually developed life.