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0 pointsdavedx7y ago0 comments

More CO2 = more warming. The polar regions are so far seeing the most extreme temperature increases: see e.g. https://static.skepticalscience.com/pics/ArcticTC1880-2010NC...

Higher arctic temperatures = permafrost melts, releasing trapped methane. e.g. https://www.nature.com/articles/d41586-019-01313-4

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4 comments · 1 top-level

assblaster7y ago· 3 in thread

So CO2 --> methane is an indirect link at best, and methane levels have been increasing linearly for the last thirty years.

https://climatenexus.org/wp-content/uploads/2019/05/ch4_tren...

There is no magical CO2 level of 400 that suddenly causes methane to be released from permafrost.

brylie7y ago

You might be reading the post too literally.

The 400 PPM is a target that is easy for humans to discuss. The general idea that increased atmospheric CO2 leads to accelerated methane releases due to thawing of arctic permafrost still holds true, and humans need to set CO2 targets to mitigate this issue.

assblaster7y ago

What's implied with a 400 CO2 level is that anything under that is fine, but above that level it triggers a calamitous increase increase methane and a so called runaway greenhouse effect. This is simply not accurate, especially because the clathrates can release methane far below 400ppm.

The CO2 level should be far lower than 400... A level closer to 200ppm should be the target.

dTal7y ago

The fear is that there is indeed a critical threshold beyond which the release of methane will form a self-sustaining feedback loop - hence the "gun". Nobody knows for sure whether this can happen, or at what level, but it's a sufficiently terrifying possibility to warrant talking in terms of thresholds we should really try to avoid. 400 is just a nice round number. The next nice round number, 500, is quite nasty even without the clathrate gun (2-3 degrees of warming).

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