The numbers appear to be more or less made up.
http://nostalgebraist.tumblr.com/post/143718406034/the-future-of-humanity-institute-seems-very
That seems like an accurate analysis.
I'm actually more concerned about an error in logic. If one estimates a probability of say k that in a given year that climate change will cause an extinction event, then the probability of it occurring in any given string of years is not the obvious one, since part of what is going on in estimating k is the chance that climate change can in fact cause such an incident.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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