The only flaw I can see in this seemingly logical interpretation of the risk is that the risks in the top left box and the risk in the bottom right box are EQUAL. What he sluffs off as a worldwide depression in the left box is the same as what he calls a catastrophe in the right box. The results are the same people die, economies collapse, health fails, people fight, and catastrophes happen.
Did you stop to think that suppose the earth did warm up. The now frozen areas would thaw and become habitable and agriculturally feasible. Canada and Siberia property values would soar. This has actually happened before....How do you suppose an island now covered in ice was named Greenland?

__________________
"Most people can't think, most of the remainder won't think, the small fraction who do think mostly can't do it very well. The extremely tiny fraction who think regularly, accurately, creatively and without self delusion---In the long run these are the only people that count."Robert Heinlein