…via Watts Up With That?
On the matter of Earth suffering the fate of Venus [boldface emphasis in the original, italics emphasis added]:
- Venus is closer to the Sun. Venus is aprox 0.72 AU distant from the sun (72% of Earth’s), with a total solar irradiance (TSI) almost 2x that of Earth.
- Venus has a denser atmosphere. The pressure on Venus is 93x that of Earth, the equivalent of almost 1 kilometer under the ocean. This is probably the largest factor causing its high temperature.
- The clouds of Venus are mostly sulphuric acid (not water vapor)—a powerful greenhouse agent.
- The atmosphere of Venus has nearly 3000x more CO2 than Earth’s atmosphere. Venus is 96.5% CO2 by volume vs 380 [parts] per million for Earth (0.038%). Goldblatt el al say that with CO2 at 30,000 ppm Earth would have “no stable temperate climate.” That would require burning 10x more than Earth’s estimated fossil fuel resources.
On the matter of Earth’s own history. From our Eocene period (56 million to 34 million years ago, the age when mammals began taking over from the dinosaurs):
- With the solar constant 1% less than today and a few thousand ppmv CO2, the mean temperature was 10oK (roughly 20oF) warmer than today. With CO2 and temperature both higher then than we expect in the foreseeable future, this implies that an anthropogenic runaway greenhouse is unlikely.
- We expect a runaway greenhouse on Earth 1.5 billion years hence if water is the only greenhouse gas, or sooner if there are others.
That last, especially, would seem to be a period beyond the useful timeframe of even the most hubristic climatista’s policy demands.