Review of Economic Studies · 2020 · Terrence Iverson、Larry S. Karp
中文摘要
我们研究一个动态博弈中的马尔可夫完美均衡。在该博弈中，行为人具有非恒定时间偏好，分散决策的家庭决定总储蓄，规划者选择气候政策。本文首次在一般折现设定和一般函数形式下求解这一问题。在时间不一致偏好下，允许规划者为多个时期选择气候政策的承诺机制可能具有很高的价值。然而，我们的定量结果表明，尽管永久性承诺机制会非常有价值，但将政策承诺维持“仅仅”100年的能力，所增加的价值不足无承诺情形下气候政策价值的2%。我们以解析方式求解了模型的对数线性版本，得出一个最优碳税公式，该公式将Golosov等（2014，Econometrica，82，41–88）中的公式作为特例包含在内。更重要的是，我们开发了新算法，以数值方法求解这一一般博弈。凸性损害导致各代规划者之间的策略互动，使最优碳税相对于无策略互动的情形降低了45%。
Abstract
Abstract We study the Markov perfect equilibrium in a dynamic game where agents have non-constant time preference, decentralized households determine aggregate savings, and a planner chooses climate policy. The article is the first to solve this problem with general discounting and general functional forms. With time-inconsistent preferences, a commitment device that allows a planner to choose climate policy for multiple periods is potentially very valuable. Nevertheless, our quantitative results show that while a permanent commitment device would be very valuable, the ability to commit policy for “only” 100 years adds less than 2% to the value of climate policy without commitment. We solve a log-linear version of the model analytically, generating a formula for the optimal carbon tax that includes the formula in Golosov et al. (2014, Econometrica, 82, 41–88) as a special case. More importantly, we develop new algorithms to solve the general game numerically. Convex damages lead to strategic interactions across generations of planners that lower the optimal carbon tax by 45% relative to the scenario without strategic interactions.