How wonderful. Humanity has apparently taken one more brave step toward immortality. Or so the story goes. In reality, we have done nothing of the sort.
We are currently hovering just above 400 parts per million of CO₂ in the atmosphere. If you are completely detached from anything resembling bioscience, that number may sound terrifyingly large. It isn’t. It translates to roughly 0.04% of the air you breathe. Feel better yet? Does it still sound like a planetary overdose?
For context, oxygen — the molecule humans require in order not to suffocate — sits at about 21%. That is more than 500 times the concentration of CO₂. Reduce oxygen just a little, say to 15%, and we are in serious trouble. Life would take a dramatic step backward on the evolutionary ladder, and it is far from guaranteed that humans would remain on it at all. And note: 15% less oxygen is still roughly 375 times more abundant than CO₂ is today.
And yet, we would struggle.
Now flip the picture. What oxygen is to us, CO₂ is to plants. And animals — inconveniently for some narratives — depend on plants for survival. That means plants are living on a diet roughly 500 times thinner than ours. And they are not luxuriating in abundance. They are hovering close to the lower physiological limit.
Below roughly 150 ppm of CO₂, widespread plant death sets in. And with it, the entire biosphere follows. No plants, no food web, no planet worth discussing. This is not speculation; it is basic plant physiology.
Which leads to the truly uncomfortable conclusion: we do not need less CO₂. We need more. And indeed, when CO₂ rose slightly, the planet greened. Satellite data shows it clearly. That greening was not a coincidence. It was plants quietly saying thank you.