The air that we breathe

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The internal combustion engine has been with us since the 1700s. By 1890 a fella named Otto Benz (yep, of Mercedes-Benz) had put one in a motorcar and made a successful business of selling them.

The basic design of the engine hasn’t really changed much since then. Air is mixed with liquid fuel and introduced into a combustion chamber where the mixture is caused to explode. In most car engines the explosion drives a piston ,which turns a crankshaft, which makes the car go down the road. In a modern internal combustion engine, say an 8-cylinder, these explosions will happen 24,000 times per minute at 3,000 RPM, which is about what your engine is turning at average highway speeds.

About a third of the energy in the gasoline drives the car down the road. Thirty percent. The rest is dissipated into the atmosphere as heat.

It’s no coincidence that most of the fossil fuels we burn for energy have this same ratio of usable power generation to waste heat. The ratio applies to jet aircraft, coal-fired power plants, semi-trucks, motorcycles, trains and guns, which are single-stroke internal combustion engines.

The efficiency ratio is built into the laws of thermodynamics, which you could consider simply the nature of the world, in that there is no getting around them. The temperature of the exhaust automobiles produce is around 700 degrees F. and 24,000 times a minute tiny explosions from just this one car are pumping heat into the air. There are about a billion cars on earth. You may think you are going down to the market or up to the lake, driving to work or school, but two-thirds of what you are doing is warming up the atmosphere.

It’s not just by pumping out scalding air that you are warming things up. You are converting gaseous oxygen into carbon dioxide and water, mostly, while extracting the chemical energy in gasoline. And very subtly changing the composition of the air we breathe. An internal combustion engine only works when there is a much cooler atmosphere to discharge the exhaust gases into. And you can only survive a trip to the store by sharing the poisons you generate with the world.

It’s a wonder that the earth has so much oxygen in its atmosphere. Gaseous oxygen is a very reactive molecule, always ready to rust out your car, brown your apple slices, burn your house down. Oxygen is so chemically eager to do this, the question really is why there is so much of it in the atmosphere that hasn’t reacted with something already. There is just enough of it in the mix of gases that make up our atmosphere to trap a layer of air against the surface of the planet where the temperatures are such that human life is possible.

In earth’s history, it has been an exceedingly brief moment so far. During most of the last 4.5 billion years since the planet hardened up, a human would not have survived one miserable minute on the surface of the earth. The mix of gases was poisonous. And deadly hot.

The oxygen in the air got there primarily by the activity of a type of bacteria that learned to harness solar power early in earth’s history. Cyanobacteria have been around for 3.5 billion years and have been gobbling up carbon dioxide and spitting out oxygen the whole time. They pretty much invented photosynthesis.

It seems to have taken them a couple of billion years to remove enough carbon dioxide and add enough oxygen to produce an atmosphere where complex life forms were possible. Before that, the proteins we are made of would have simply melted. These organisms, really as much plant as animal, took roughly half the earths history to create an atmosphere that was precisely 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon and 0.04 percent carbon dioxide.

This ball of mixed gases trapped just enough of the sun’s radiation in a shell a couple of miles thick above the surface of the planet to produce temperatures, in some places, where liquid water could exist. That it happened on earth is the central miracle of creation. The surface of the sun is 10,000 degrees F., interstellar space about 0.000000005 degrees F. Water is liquid within a 180-degree range. What are the chances?

We are changing the atmosphere back to what it used to be – poisonous and hot – undoing the work of zillions of lowly bacteria, over billions of years, in a geologic instant. It’s not sunspots, normal weather variations, too many trees or any of the other BS stories we tell ourselves. It’s us.

The concentration of C02 in the air has increased by 50 percent since the beginning of the industrial revolution. It’s unprecedented in human history. The consequences are already upon us and plain as the nose on your face or the smoke in your eyes. Yet we dither and deny.

I doubt the cyanobacteria were making oxygen on our behalf, though it’s hard to say what  bacteria might be thinking. They obligingly spend quadrillions of generations making enough oxygen that a person can turn it into heat and poisonous gas and a little travel down the road or often, in this country, a pointless circle in a Lazer. We are undoing their work, though my guess is they probably don’t much care. I don’t think they had any idea what they were doing.

Neither do we.

Tim Cooper writes from Montezuma County, Colo.

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