Levels of global catastrophes: from mild to extinction
It is important to make a bridge between existential risks and other possible risks. If we say that existential risks are infinitely more important than other risks, we put them out of scope of policymakers (as they can’t work with infinities). We could reach them if we show x-risks as extreme cases of smaller risks. It could be done for most risks (with AI and accelerator's catastrophes are notable exceptions).
Smaller catastrophes play complex role in estimating probability of x-risks. A chain of smaller catastrophes may result in extinction, but one small catastrophe could postpone bigger risks (but it is not good solution). The following table presents different levels of global catastrophes depending of their size. Numbers are mostly arbitrary and are more like placeholders for future updates.
http://immortality-roadmap.com/degradlev.pdf
Arctic news is generally not credible, using incredibly stupid polynomial fits to observed methane levels at single surface stations to infer absurd and impossible levels in the near future and generally hyping all the positive feedbacks they can find an inkling of in the literature and ignoring every known negative feedback.
As well as the fact that the Earth has been through massive atmosphere excursions in the past from much higher greenhouse condition starting points, like the Paleocene Eocene Thermal maximum or the Permian event, without ever leaving the bounds of long-term homeostasis. The next half milion years stand to be VERY interesting for the biosphere, but this has happened before no matter what scale we push things to.
While I don't agree with everything arctic news say and I see that they overhype some recent small changes in methane concentration, I heard the idea of runaway global warming before. I also think that artificial runaway global warming is possible if nukes will be used to destabilize methane of ocean floor. While answering previous comment I was surprised to find in wiki that if median earth temperature once rise to 47C, than water vapor greenhouse effect will push it until new stable state at 900 C. I still think that we should be more afraid of small pro... (read more)