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Comment by marliechiller | Hacker News Reader

Correct me if I'm wrong, but isn't it the case that whilst methane is many times worse than CO2 in terms of its warming effect, it also has a much shorter "half life" than CO2 - in the region of a few years before its no longer having an effect on warming. Not to minimise the fact that we should be avoiding contributing to global warming in any way possible, but comparing it to coal therefore is apples to oranges

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You aren't wrong but comparison requires some context. Because of the decay comparisons are made over a time period, the EPA typically uses 100 years. It uses a factor of about 28x, ie methane retains 28x more heat than an equal amount of co2 over a 100 year time period.

There's debate over whether 100 years is an appropriate time period. Many say its too conservative given the nature of the heating that we face. Over a 20 year time frame the ghg factor is 84x. This has implications particularly when people think about feedback effects, ie methane increases heat which causes permafrost to melt and release more methane which increases heat, etc. Another feedback effect making the picture more complicated is that the decay rate of methane in the atmosphere decreases as the concentration increases.

However you cut it, methane in the atmosphere is increasing more rapidly than co2 despite its decay. Reducing it gives a lot of bang for the buck given that in industry most of the emissions come from a relatively few points in the infrastructure. There are of course other sources which are very challenging to reduce like agriculture.

To build on the context, I is also worth pointing out that with both CO2 and methane, the vast majority of the heating doesn't come from the molecules themselves, but water vapor.

The ghg potential for each is based on the 2nd order system impact and interaction with water vapor.

It isnt nearly as simple as some reactive index of the molecule itself

Methane in the atmosphere breaks down to CO2 and water, so even if the methane is gone, it leaves a lasting heating effect in its wake.

Edit: And its over 80 times (!) more warming than CO2 over a 20 year period.

https://theconversation.com/climate-explained-methane-is-sho...

Where is this persistent falsehood coming from? It's getting posted on every recent story about climate change.

Presumably someone with connections to big methane producers is spreading it?

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