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Comment by SubiculumCode | Hacker News Reader

I have at times worried about the trapped methane that could be released with the permafrost...on some accounts I've heard the amount that could be released is massive. I know that this methane can increase global warming, but I have another fear. Although perhaps farfetched, is it possible that climate change could release a dense, rolling methane cloud that can asphyxiate whole populations?

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The molecular mass of oxygen gas is 32 and the molecular mass of methane is 16. The methane will tend to rise and mix, leaving plenty of oxygen near the surface. It's unlikely to asphyxiate humans unless it happens really, really fast.

People and animals have been asphyxiated by massive CO2 releases because they can happen very quickly, and CO2 has a molecular mass of 44, making it stay near the ground for longer, displacing lighter oxygen and nitrogen gases.

Isn't density not mass the issue? Methane still floats above air using density from the internets, though I wonder about mixing

0.656 kg/m³ methane

1.98 kg/m3 carbon dioxide

1.225 kg/m3 air.

Atmospheric gases under typical conditions behave pretty much like ideal gases, which means it doesn't matter whether you talk about density or molecular mass; they're directly proportional to each other. And the molecular mass is independent of temperature and pressure.

No. That is not a concern on any kind of level.

Quick look indicates asphyxiation at 16-21%. At 5-15% concentration it is explosive. Current levels are about 2000 parts per billion.

It will not release that quickly on anything more than a localized level, and it would probably kill you via explosion, first. Since it would be gradually released we would all be long dead from the greenhouse effect.

There are concerns about old diseases that might have been conserved in the permafrost and that could be released as it melts though.

The ocean has already started to asphyxiate [1].

[1] https://news.nationalgeographic.com/2018/01/climate-change-s...

https://www.sciencedirect.com/science/article/pii/S1871174X1...

Maybe not gas clouds of rolling death, but some think it would be pretty catastrophic.

Methane is lighter than air and thus would rise up to the sky until mixed.

Very few people live in permafrost areas, so it won't be a massive problem. Something like Lake Kivu on the other hand...

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