Given the relentless drumbeat of terrifying claims about the alleged perils of global warming, uninformed people might be inclined to assume that human use of fossil fuels is causing so much havoc that the atmosphere is in danger of being dominated by carbon dioxide, the most vilified molecule in history.

As a matter of scientific fact, CO2 comprises a virtually infinitesimal part of the air that blankets our planet.  Over geological time, CO2 has reached as high as 8,000 parts per million. The current concentration of 400 parts per million is at the low end of the average over millions of years.

By percentage, the most prevalent atmospheric gases are nitrogen (78%) and oxygen (around 21%), followed by argon (less than 1%).  Trailing far behind is carbon dioxide, which comes in at a miniscule 0.04%.  In other words, 99.96% of the atmosphere is something other than CO2.

Both sides of the climate debate agree on three things: that CO2 has some effect on warming, that the planet has warmed over the last century, and that CO2 levels have gone up over the same period, from 0.03% to 0.04%.  That's an increase of 0.01%, or 100 parts per million, which can also be expressed as ten parts per 100,000.

Ten parts per 100,000.  Please keep that ratio in mind for a moment.

To get a visual of what an astonishingly tiny portion of the atmosphere is made up of the increased amount of CO2 that's appeared over the last century, take a look at the University of Alabama's Bryant-Denny Stadium, which has a seating capacity of slightly more than 100,000.  Consider that just ten of those 100,000 people in the stands represent the visual equivalent of the increased level of CO2 in our atmosphere.  Just ten.  Ten of the football fans in the jam-packed stadium represent the increased amount of CO2.  The other 99,990 fans represent the rest of what's in the atmosphere — i.e., everything except the increased amount of CO2.

Image courtesy of StadiumArt.com, the No. 1 source for posters and art prints of some of America's most storied sporting venues.

I'm not a climate scientist, or a scientist of any kind.  But I do have an engineering degree, which I mention only to point out that I'm at least as qualified as most non-scientists to form rational opinions regarding claims about the climate.  Maybe I'm off base, but it doesn't seem plausible to my layman's mind that a microscopic increase in one of the least plentiful atmospheric gases (CO2) is causing the environment to fall apart at the seams.

But just because an atmospheric condition may not seem plausible to a non-scientist like me, that doesn't necessarily mean it's not plausible.  As pointed out to me by Princeton physicist Dr. William Happer, who has studied the atmosphere for 50 years, adding a 0.04% concentration of strychnine to the public water supply would put quite a dent in the world's alleged overpopulation problem.  Although carbon dioxide has been demonized as the atmospheric first cousin of strychnine, it is, in fact, a critically important substance that benefits the entire world by increasing crop and forestry yields.  More CO2 equals higher yields, no doubt about it.  As Dr. Happer noted, CO2 is neither a "poison" nor a "pollutant," and its small increase over the last century can be somewhat compared to giving a barn a coat of good-quality red paint: adding a second coat makes almost no difference in how red it looks.  The theory that rising levels of CO2 will cause climate collapse is just that, a theory, and a hotly disputed one at that.

There's another possible reason why the planet has warmed over the last 100 years, and it has nothing to do with carbon dioxide.  Earth's climate has always been in a state of flux.  For billions of years, our planet has experienced warming trends followed by a cooling trend, followed by another warming trend, and so on.  That one-followed-by-the-other pattern is unbroken, dating to the time the atmosphere first formed, so maybe the warming trend over the last century was just another event in that timeless pattern.  In other words, maybe the warming was merely coincidental to the slight increase in CO2.

The peddlers of climate fear have misled us before

In the 1970s, environmental alarmists warned us that Earth was descending into a cataclysmic cooling trend.  But that chilling prediction proved wrong when the planet unexpectedly began warming the very next decade.  From the early 1980s through 1997, an undeniable warming trend set in.  The same people who tried to terrify us with the specter of an impending mini–Ice Age changed their spiel on a dime, and began telling us that the warming was spiraling catastrophically out of control, with no end in sight.  But they were wrong about that, too.  Beginning in 1998, the accelerated warming trend unexpectedly ran out of steam, and remained in a virtual flatline for nearly two decades, a period when ever increasing anthropogenic CO2 emissions were steadily being pumped into our immensely complex — and immensely resilient — climate.  If the peddlers of climate fear ever make you worry that CO2 is staging a hostile takeover of the atmosphere, remember the picture of Alabama's football stadium.

An electrical engineering graduate of Georgia Tech and now retired, John Eidson is a freelance writer in Atlanta.  American Thinker recently published related articles of his titled "The Obamas tackle climate change and wealth inequality"; "Harrison Ford, Climate Hypocrite"; and "A $600 fill-up?"