A rather windy explanation of global warming

I have put off writing about this column topic as long as I possibly could. I haven’t wanted to write about big scientific problems. I’ve preferred dealing with more common events that can be explained on a scientific basis. Science sometimes seems overly dramatic and breathless when, actually, it can be a lot of fun.

However, when it becomes necessary to address significant social issues, the scientist must be especially sensitive. Please be advised that I undertake this topic reluctantly. I’m writing about it only because of the continued debate concerning climate change.

Flatulence has been shown to be surprisingly significant in the consideration of global warming. Flatulence is the term used for gases produced by some bacteria as they metabolize incompletely digested food in the intestines of animals. The majority of these bacteria share a common metabolic pathway that produces methane.

These bacteria are very small, and measure only about 5,000th of a millimeter. Picture tiny bacteria floating on their backs in the primordial fluids of the intestine and blowing still-tinier bubbles of methane. I don’t suppose their methane bubbles could be any bigger than 100,000th of a millimeter.

Not being particularly soluble in water, though, these bubbles tend to come together into surprisingly large volumes. However, the methane is trapped in the intestine until such time as it can be moved to a convenient opening.

Methane is a potent greenhouse gas. It is estimated that it has as much as 25 times the climate-warming potential of carbon dioxide. Now, consider this: Humans have flatulent episodes about 14 times a day on average. This amounts to anywhere from 1 to 4 pints of gas per day per person.

There are some 7 billion humans on the face of the earth, so humans are producing at least 7 billion pints of gas a day. That amount could be as high as 28 billion pints. Since “a pint is a pound the world around” that is between 7–28 billion pounds, or 14 million tons of gas. Admittedly, not all human flatulence is composed of only methane. There are other variable, and often unidentified, components.

Still, we are not the major producers of greenhouse-inducing methane. Cows, sheep, goats, giraffes, antelope, water buffalo and other plant-eating ruminants are larger animals, and their diets encourage rich methane-producing intestinal inhabitants. It is estimated that, collectively, all modern ruminants emit between 50 million and 100 million tons of methane per year.

Add that to the 14 million tons of human flatulence, and you get an impressive total. If methane is 25 times more active in greenhouse warming, then this volume would be equivalent to 2.85 billion tons of carbon dioxide.

Extrapolating backwards (see previous columns on imagination and extrapolation) one might guess that prior to the Industrial Revolution there were even more ruminants on the Earth and therefore more methane. Estimates are that at one time methane production from animal flatulence may have been as high as 200 million tons per year.

Extrapolating further, Sauropod dinosaurs apparently lived on the earth 150 million years ago. These enormous creatures weighed about 44,000 pounds and were plant eaters. In some places there were as many as a few dozen Sauropods per square mile. Presumably, because of their diet, they produced methane in their flatulence. In fact, calculations based on their size and density indicate that they may have produced more methane than all modern sources — man-made and natural — combined.

So we see that climate change and global warming are nothing new. Climate change probably occurred back in the Mesozoic and was the probable cause of dinosaur extinction. (OK, that is wild speculation on my part)

I hope I have handled this difficult column with the taste, dignity and urgency it deserves. The obvious conclusion to this column is that the best thing we can do to combat climate change is for everyone to stop expelling gas. 

Gary McCallister, .(JavaScript must be enabled to view this email address), is a professor of biology at Colorado Mesa University.


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