Carbon dioxide (CO2) comes up a lot these days, in politics, in media, and increasingly in daily life, a trend I hope continues as the urgency of global warming overwhelms our inaction, but just how we perceive this CO2 and its climatic counterweight, oxygen, is very nuanced, and very important.
CO2 is not merely a greenhouse gas, you see, one of a series of compounds noted for their trapping of solar heat in our lower atmosphere. CO2, in a very real way, represents chemical deadness.
Oxygen is not the default position of most atmospheres and is by no means a given. Oxygen is so chemically active that it will bond almost indiscriminately, to iron forming rust, to hydrogen forming water, and to carbon, forming CO2. Ask any planet in our solar system; they’ll tell you that free floating oxygen is a rarity, a privilege, an otherworldly accident perpetuated not just by good fortune, but by a healthy, functioning biosphere, an artificial arrangement between flora and photons, between climate and evolution.
Take away Earth’s biosphere and, slowly but surely, the 21 per cent of its atmosphere conquered by oxygen will react away with whatever is close at hand, turning a once unique, interesting and lively planet into something inert, carbonized, sterilized, and it’ll stay that way without some mechanism for renewing the independence of oxygen.
Consider Mars. There but for the miracle of life go we, a planet whose atmosphere is very thin, and almost entirely composed of CO2. And that’s how it’ll remain. This CO2 is happy, non-reactive and in no terrible hurry to do anything interesting, like accommodating our lungs. If life is a sort of self-perpetuating motion, turning and reviving its host planet into something more than the sum of its elements, the universality of CO2 represents the failure of that motion, its cessation and surrender.
Let’s look to the heavens once more, this time at Venus, its surface permanently obscured by a writhing cloud of acid, heat and abstract rage, shining so brightly that historic peoples named it for the Roman goddess of beauty and love. On closer inspection we see that, in reality, it’s the god of carbon.
What has been called the “runaway greenhouse effect” played out on Venus a long time ago, where the collected carbon of its atmosphere trapped so much heat that still more carbon was baked out of the planet’s crust. This heat became so intense (roughly 500°C on the surface) that liquid water became impossible, oceans worth vapourizing into the dense clouds which continue to suffocate the planet’s surface. Free floating oxygen is a laughable prospect on Venus.
What about methane, known among chemists as CH4? Is it not a chemically dead consequence of cows and fracking wells? No. Methane is a greenhouse gas to be sure, and a serious one, but its seriousness changes over time because it, like oxygen, it’s reactive. Over a 20 year period, methane is 75 times more potent a driver of global warming than CO2, but over a 100 year period it’s only 20 times more potent. This is because methane reacts with its surroundings and changes over time, slowly converting itself into, you guessed it, more CO2, and water, another relatively settled compound.
Just as lightning finds the ground and water flows inexorably downward, the Earth’s atmosphere tends naturally toward CO2, toward chemical deadness. Were it not for the health and vitality of our biosphere and all its composite parts, Earth would not be unlike Venus, its gases settling into a comfortable quiet, its heat building and building until the oceans boil and our magnificent surface becomes obscured forever under violent, angry clouds.
We have become the harbingers of carbon, accidentally at first, but now with full knowledge of its consequences. Governments and industry both bicker and bluster about how much more we should or should not be allowed to emit when too much could cost us more than simple prosperity. Not only are we still emitting more carbon each year, we are strategically disassembling the biosphere which combats it. Such swells of carbon have happened before on this planet, each marked by mass extinction.
So far as chemistry can inform morality, we should feel obligated to choose the liveliness of oxygen over the deadness of carbon.
Zack Metcalfe is a freelance journalist, columnist and author active across the Maritimes.
The Blue Marble is a famous photograph of Earth taken on December 7, 1972, by the crew of the Apollo 17 spacecraft en route to the Moon at a distance of about 29,000 kilometres. It shows Africa, Antarctica, and the Arabian Peninsula. (NASA photo)