Well, I Guess Global Warming Could Be A Problem

Here's something interesting. Why is Venus so much hotter than Earth? Silly me, I had always assumed it was because it was so much closer to the sun. But that is apparently not the case. According to a column by Gwynn Dyer*, the real reason is global warming run amok:

Earth and Venus are almost exactly the same size, and there is not all that huge a difference in the amount of heat they get from the Sun: Earth's orbit is an average of 93 million miles away, while Venus orbits at 67 million miles.

The average temperature on the surface of our planet, at least since life appeared some 3.5 billion years ago, has always stayed between 50 and 68 degrees. On Venus, in shocking contrast, it is 869 degrees. That is hot enough to melt lead.

The immediate reason for the difference is obvious enough: Venus's atmosphere is 90 times thicker than the Earth's, and it is 98 percent carbon dioxide. It is the runaway greenhouse effect produced by that deep, dense blanket of CO2 wrapped around the planet that causes the incredible surface temperatures.

And, it turns out, the reason that Venus has all that CO2 is that it has no life:

Venus is the lost, evil twin of Earth, and it tells us what Earth would be like without life. Living things have taken almost all the CO2 out of the atmosphere, incorporating the carbon into their bodies or burying it in chalk and thus releasing the oxygen to create the atmosphere we have today. The current balance of the Earth's atmosphere - 99 percent nitrogen and oxygen and almost no CO2 - is highly unstable, but the activities of living things have kept it the way it is for several billion years. That, in turn, keeps the Earth cool enough for life to flourish here.

How's that for circularity: Venus has no life becuase it has too much CO2; and it has too much CO2 becuase it has no life. Earth, by cantrast, has life becuase it has very little CO2; and it has very little CO2 becuase it has so much life.

Dyer explains that anomoly thusly:

Here life released the oxygen and fixed the carbon, leaving just enough carbon dioxide in the atmosphere (about 0.03 percent at present) for a mild greenhouse effect - and presumably modified that level of CO2 as the sun heated up in order to keep the average temperature in the narrow band that is optimal for carbon-based life.

Whereas if life did get started on Venus and began to transform that planet's atmosphere as it changed the Earth's, at some point it was unable to keep up with the rapid accumulation of CO2 and fell victim to a runaway greenhouse effect.

Fascinating.

* I originally read this in the Toledo Blade, but since the Blade does not put wire service reports or syndicated columnists on its website, I had to go elsewhere (Salt Lake Tribune) to find a link.