Climate Economists Deftly Tackle their Second-Hardest Question

Among economists, "What's the future worth?" has been one of the most chewed over questions since the U.K. released a major assessment of the costs of climate change in 2006. There are plenty of answers that the question brings up in ordinary life, from the emotional ("Every bit as much as the present!") to the practical ("How will answering this question help my re-election to the U.S. House of Representatives?")

In the world of climate change, though, it's a hard numbers question: how much should we spend now to head off climate disaster in the future? It depends on how much you think the value of money will change over large spans of time. Economists talk about the value of the future in terms of a "discount rate": how much we value a dollar's worth of goods or resources X years in the future compared to today.