“The irony,” says Schneider, “is that this possibly unconnected event has brought us to the right level of consciousness about the problem, a level that should have been reached about fifteen years ago. The point is that there is no controversy—none—about the existence of the greenhouse effect. It’s the best established theory in the atmospheric sciences.”
As evidence, there is the Goldilocks phenomenon: the wildly differing conditions on three neighbor planets: Mars, Venus, and Earth. The atmosphere of Mars is about 95 percent carbon dioxide, but it is exceedingly tenuous, more than 100 times thinner than Earth’s. So little of the sun’s heat is trapped by the atmosphere that the planet is colder than a deep freezer. Winter at the Martian poles brings temperatures of minus 180 degrees F. That’s too cold for life,
Venus lies at the other end of the gamut. Its atmosphere, 97 percent carbon dioxide, is very thick. The pressure at the Venusian surface is 90 times Earth’s. As a result, Venus has been called a ‘”runaway greenhouse,” If Mars is like a deep freezer, Venus basks in the temperature of a self-cleaning oven, about 900 degrees F— too hot for life.
Schneider demonstrates that Venus is hot because of its very thick atmosphere, and not because of its atmospheric chemistry, and then concludes that the heat must be due to its atmospheric chemistry.