CO2 is not itself the only cause of global warming. Rather, Flannery says, its ability to "trigger" the production of water vapor is far more important. It creates a "feedback loop": CO2 warms the air thus producing more H2O vapor which warms the air even more, then CO2 warms this new air, etc. H2O vapor also makes up the clouds which play a dual role. Thin high flying clouds reflect heat energy back into space, low flying thick ones trap it and warm the atmosphere. The CO2 generated by fossil fuels is responsible for 80% of global warming as a result of these processes. One of the reasons it is so dangerous is its longevity in the atmosphere. Flannery points out that 56% of the CO2 generated in the last couple of hundred years is still in the atmosphere.

Where does most of it come from? We are told it's from all the billions of motors we have made that run on fossil fuel. "Most dangerous of all are the power plants that use coal to generate electricity." It looks like every new coal fueled power plant is another nail in the coffin of our planet. The next most dangerous greenhouse gas is methane: CH4. This mostly comes from natural gas.

Nature has its own ways of removing carbon gases from the air-- unless we overload the system (which is what our profit driven capitalist system is doing ). The forests and the oceans have been thought to be the biggest carbon "sinks" but recent research has shown that only the oceans really count-- from 1800-1994 they stored 48% of the carbon put out by our system "while life on land has actually contributed carbon to the atmosphere."

Now we need a little history. Genetic analysis shows that about 100,000 years ago there were only about 2000 breeding members of our species on Earth. A very small population. Now there are six billion of us (not all of us breeding). About 10,000 years ago some of us took up agriculture and the industrial civilization of today is the result. There are still pockets of humans, in the Amazon for example, with cultures untouched by developments of industrial civilization (but not for long).

All humans lived as hunter gatherers until the agricultural revolution. There is no evidence that we are any smarter today than then, or that present day hunter gatherers are any less smarter than their city dwelling cousins. So what were we doing for 90,000 years until agriculture came along. Why didn't we become agricultural much sooner?

Scientists have been taking ice cores from the poles and from glaciers around the world. These reveal that violent climate changes and alternating ice ages and warm periods were taking place on and off throughout the period of our early gestation. These periods show major CO2 fluctuations also occurring and being responsible for climate changes. But these CO2 fluxes were of natural origin. What is going on today is caused by our industrial system.

The last great ice age, of many, lasted from 35,000 to 20,000 years ago. Around 20,000 years ago another natural flux towards global warming began which led, by 10,000 years ago to the climate we have today. Between 20,000 and 10,000 years ago the Earth warmed up by 9 degrees F. This was a little under an increase of 2 degrees F per 1000 years.

But with our coal power plants and other fossil fuels we are slated to heat the Earth between 2 to 8 degrees F in this century alone. This will be an unmitigated disaster for life on Earth. It will lead to the greatest extinction event (it has already begun) since the end of the Age of the Dinosaurs 65 million years ago. [Since birds are dinosaurs they are not technically extinct, scientists tell us.]

The long warming period that began 20,000 years ago was marked by a zig zag back and forth between alterations of hot and cold climates which finally stabilized about 8000 years ago in what scientists call "the long summer" [i.e., the climate since the agricultural revolution]. So what were humans doing up until then? Well, with the coming of the long summer we slowly left our caves and huts, populations increased, agriculture led to the founding of early civilizations.... and here we are.

Part Three coming next Wednesday.