4 ms·

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

• brylie 7y 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.
  • assblaster 7y 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.
• dTal 7y 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).