David Spratt at Mother Jones:
Would you live in a building, cross a bridge, or trust a dam wall if there were a 10 percent chance of it collapsing? Or 5 percent? Or 1 percent? Of course not! In civil engineering, acceptable probabilities of failure generally range from 1-in-10,000 to 1-in-10-million.
So why, when it comes to climate action, are policies like carbon budgets accepted when they have success rates of just 50 to 66 percent? That’s hardly better than a coin toss.
Policy-relevant scientific publications, such as those produced by the Intergovernmental Panel on Climate Change (IPCC), focus on the probabilities—the most likely outcomes. But, according to atmospheric physicist and climatologist Hans Joachim Schellnhuber, “calculating probabilities makes little sense in the most critical instances” because “when the issue is the survival of civilization is at stake, conventional means of analysis may become useless.”