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Comment by BWStearns | Hacker News Reader

Doesn't methane get reacted away in a relatively short (≈years) period of time?

No, that’s the problem. The GWPs usually quoted are over 20 years (GWP 81.2) and 100 years (27.9), but over 500 years it’s still around a GWP of 8.

Depends on your definition of a ‘long time’ but it’s not like it reaches the low single digits even after 500 years…

Atmospheric methane oxidizes into CO2 and water vapor. Then the CO2 hangs around for much longer...

https://en.wikipedia.org/wiki/Atmospheric_methane#Natural_si...

yes eventually, but until it does it is a far worse greenhouse gas than CO2

It kind of does, but calculating its actual lifetime or warming effect is tricky. This post explains it quite nicely: https://climateer.substack.com/p/methane-lifetime

It converts to more CO2, and is also worse than CO2 during the short time

Which is irrelevant if the input carbon was atmosphere sourced anyway.

no, it isn't. Over the course of a few decades, a kilogram of methane has the greenhouse impact of ~50 kilograms of CO2 because of the different absorption modes methane has that CO2 doesn't. If terraform leaks more than a few percent of their product into the atmosphere from carelessness (who cares about tracking such a low value commodity?) Then this is worse than just leaving the CO2 in the atmosphere. I really wish they'd address this fact more. Some possibilities:

-The hydrogen half is still a great way to make hydrogen for industrial processes

-The methane can be used on site of production for organic chem feedstocks

-Many new rockets are using methane as their fuel, using it at point of origin instead of transporting through leaky pipelines and trucks.

Any analysis along these lines would be reassuring that this isn't going to be a net-negative, climate wise.

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