Catastrophic climate-change damages are characterized by deep structural uncertainties in the science combined with severe constraints on the ability to evaluate meaningfully the welfare losses. The critical question is: How fast does the probability of a catastrophe decline relative to the welfare impact of the catastrophe?

In this presentation I attempt to distill the problem down to an extraordinarily simplistic exercise in expected utility theory. Some mathematical economics is involved, but the ultra-simplification allows me to present the basic ideas in a relatively compact form that I hope will be accessible to an audience that knows at least a smattering of economics and probability.