Lomborg’s view is not just his personal opinion. It’s the outcome of the Copenhagen Consensus project. He gathers together leading economists, gives them assessments from experts on various plans for addressing different global problems, and has them apply cost-benefit analysis to the plans. The economists then rank the plans in terms of cost-effectiveness. This is all based on what subject-matter experts estimate to be the costs and the effects of the best plans that people have come up with for addressing global problems (including climate change and many other problems).

Do we still believe that groups of economists can provide reliably predictive estimates? These economists might be near correct, or their forecasts might be as useful as those made for Syria in 2009.

Sea level rise is just one of the challenges that we are facing. Humans are adaptable, however we haven't been around very long, and for the short time we have, there is historical evidence for social collapse when we are forced to adapt quickly.

Our desire for a cost-benefit analysis doesn't make one possible.