The late Carl Sagan: Not necessarily a friend of global warming alarmists?

June '06: An Inconvenient Truth

It might come off as a little alarmist, but frankly, sometimes you have to scream to get people’s attention. [Fraudster Al Gore's] passionate and has a nice sense of comic timing, but I got annoyed by how he prefaced every scientist and expert he quoted with “my friend,” as in, “my friend Carl Sagan.”

CARL SAGAN - Dot Earth Blog - Andy Revkin - NYTimes.com

The name Dot Earth alludes to the 1996 speech by Carl Sagan, in which he marveled at the minuteness of the home planet, a “pale blue dot” in the vastness of space.

1980 book: Cosmos by Carl Sagan

The principal energy sources of our present industrial civilization are the so-called fossil fuels. We burn wood and oil, coal and natural gas, and, in the process, release waste gases, principally CO2 into the air. Consequently, the carbon dioxide content of the Earth's atmosphere is increasing dramatically. The possiblity of a runaway greenhouse effect suggests that we have to be careful; Even a one- or two-degree rise in the global temperature can have catastrophic consequences. In the burning of coal and oil and gasoline, we are also putting sulfuric acid into the atmosphere. Like Venus, our stratosphere even now has a substantial mist of tiny sulfuric acid droplets. Our major cities are polluted with noxious molecules. We do not understand the long-term effects of our course of action.

But we have also been perturbing the climate in the opposite sense. For hundreds of thousands of years human beings have been burning and cutting down forests and encouraging domestic animals to graze on and destroy grasslands. Slash-and-burn agriculture, industrial tropical deforestation and overgrazing are rampant today. But forests are darker than grasslands, and grasslands are darker than deserts. As a consequence, the amount of sunlight that is absorbed by the ground has been declining, and by changes in the land use we are lowering the surface temperature of our planet. Might this cooling increase the size of the polar ice cap, which, because it is bright, will reflect still more sunlight from the Earth, further cooling the planet, driving a runaway albedo effect?