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Comment by saubeidl | Hacker News Reader

What if one started emitting Nitrogen, Oxygen and Argon in the right proportions instead to get the mix right again?

I like the unconventional approach. A few minutes with GPT raises two issues:

1. We've raised CO2 from 280ppm to 420ppm, about a 50% increase. To dilute it back down would require 50% more total atmosphere. This would also raise the surface air pressure 1.5x.

2. How much heat is trapped is related to the absolute amount of CO2 in the atmosphere, not the fraction. So the diluted atmosphere would retain just as much heat.

Would it increase the steady state surface air pressure by 50%, or would more molecules offgas into outer space to compensate?

If the latter, it might actually work. Assuming they offgas at-proportion. Which they probably wouldn’t…

Interesting thought but you would need a lot of these gasses on the one hand and on the other hand it doesn’t help in working against the greenhouse effect. The greenhouse effect depends on the absolute amount of CO2 in the atmosphere, not the percentage. How much infrared light is absorbed by CO2 primarily depends on the amount of CO2 in the atmosphere.

My naive guess is that since CO2 takes up so few percentage, you would need an unfathomable amount of N, O, and Ar to get the mix right..?

We will unquestionably reach more than twice the CO2 concentration of pre-industrial levels (which was around 280 ppm; we're at 424 ppm now, it'll increase to beyond 560 ppm in most not-super-optimistic projections).

Do you really think it's both feasible and a good idea to release so much O2 and N2 to double the mass of the atmosphere? Or even just increase it by some appreciable fraction?

For the record, the atmosphere is around 5 150 000 000 000 000 metric tons. 5 quintillion kilograms. You're talking about producing metric exatons of gas.

Wikipedia says that there's 300 000 to a million gigatons of nitrogen in the earth's crust; that's 300 teratons to a petaton (https://en.wikipedia.org/wiki/Nitrogen#Occurrence). If you extracted LITERALLY ALL THE NITROGEN IN THE CRUST, converted it to nitrogen gas and released it into the atmosphere, and we use the extremely optimistic 1 petaton estimate, you'd have increased the mass of the atmosphere by roughly 1/5000. That means you'd have decreased the CO2 concentration in the atmosphere ... by roughly 1/5000. From 424 ppm to 423.92 ppm.

Think about the magnitude you’re talking about here. Every internal combustion engine on earth is emitting CO2. Every volcano, forest fire, coal power plant, etc. The atmosphere is massive. We’ve been, basically, doing our best to pump it full of CO2 for the last 150 years, and this is what we’ve got. Ignoring the chemical challenges with your idea here, the scale is impossibly gargantuan.

These gases are refined from air to begin with.

Do they need to be?

Where else are they going to come from? They’re all basic elements, either you separate them from air, or you have to go through an energy intensive process to liberate them from various chemicals they’ve been compounded into.

But guess what, all of those chemicals are extremely valuable, such as nitrates for fertiliser, water, and Argon does really react with anything (it’s a noble gas), which is why we use it as a shield gas in processes like welding.

So producing enough of those gases to somehow offset CO2 production would first require ludicrously large amounts of energy, and if we had access to that amount of clean energy we wouldn’t even be having this discussion. Plus it requires breaking down really valuable chemicals that we spend quite a lot of energy trying to produce or preserve anyway.

Where would that come from? It's not that we have some large untapped Oxygen or Nitrogen source laying around that is not part of the atmosphere.

Would that actually reduce the greenhouse effect? Intuitively, it seems analogous to putting on a less dense, but thicker blanket.

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