Most of the commentary today on the decision to award Nobel prizes in economics to William Nordhaus and Paul Romer has focused on the recipients. I want to talk about the nonrecipient whose nonprize is perhaps the most important statement by the Riksbank, the Swedish central bank that decides who should be recognized each year for their work in economics “in memory of Alfred Nobel”.
Nordhaus was widely expected to be a winner for his work on the economics of climate change. For decades he has assembled and tweaked a model called DICE (Dynamic Integrated Climate-Economy), that melds computable general equilibrium theory from economics and equations from the various strands of climate science. His goal has been to estimate the “optimal” amount of climate change, where the marginal cost of abating it equals the marginal cost of undergoing it. From this comes an optimal carbon price, the “social cost of carbon”, which should be implemented now and allowed to rise over time at the rate of interest. In his first published work using DICE, from the early 1990s, he recommended a carbon tax of $5 a tonne of CO2, inching slowly upward until peaking at $20 in 2085. His “optimal” policy was expected to result in an atmospheric concentration of CO2 of over 1400 ppm (parts per million) at the end of this planning horizon, yielding global warming in excess of 3º C. (Nordhaus, 1992)