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ikacer comments on Open Thread, Aug. 1 - Aug 7. 2016 - Less Wrong Discussion
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Maybe someone better at statistics than me (I'll withhold my own suspicions of the answer) can answer a question:
Given that life has been around for billions of years without very many huge extinction events, it seems likely that the environment is a very stable system and runaway global warming is false.
However, if the environment is an extremely unstable system, such that runaway global warming always results in total extinction of all life, then the anthropic principle comes info effect.
So my question is: Can we actually then say that runaway global warming is a small probability event?
Well, we could look at other planets that show any sign of ever having had an Earthlike atmosphere. Here's (I think) the list of such planets we know about and are able to observe: {Venus}.
That might be a pretty bad sign, but I'm not sure Venus's history is similar enough to earth's. (E.g., whatever got its atmosphere the way it is, it probably wasn't overproduction of CO2 by burning fossil fuels. Though, actually, I'm not sure how we'd know.)
Venus doesn't have magnetic field. Because of it, Venus lost hydrogen from its atmosphere due to solar wind. Because of it Venus became very dry. So, it had not life and ways to fix CO2 in carbonates in water. It resulted in large accumulation of CO2 in atmosphere and strong greenhouse effect. It changed the way its mantle creates continents as dry mantle is not plastic. There is no plate tectonics on Venus. The surface changes every half a billion years in one large "supervolcanic" event.
There is also the little issue of Venus receiving about twice the insolation than Earth....
But Venus albedo is 0.75, while Earth's is 0.3. So Venus gets less solar energy than Earth, because of very white upper cloud cover http://www.universetoday.com/36833/albedo-of-venus/
I think that we strongly underestimate not only probability of runaway global warming but also fragility of our environment because of anthropic bias.
May be runaway global warming is long overdue in our planet and small human actions could trigger it.
I wrote an article about it several years ago, but I want to rewrite it completely. The current version is here: "Why anthropic principle stops to defend us: observation selection, future rate of natural disasters and fragility of our environment" http://www.slideshare.net/avturchin/why-anthropic-principle-stopped-to-defend-us-observation-selection-and-fragility-of-our-environment