Learning about climate change and implications for near-term policy
Learning about climate change and implications for near-term policy
复制标题
了解气候变化及其对近期政策的影响
DOI：
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发表时间：
2008
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通讯作者：
J. Norton
中科院分区：
文献类型：
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作者：
M. Webster;Lisa M. Jakobovits;J. Norton
气候变化是一个风险管理问题。令人关切的最重要原因不是对未来气候变化的中等预测，而是低概率、高后果的影响。因为政策问题是在不确定性下的连续决策问题，我们不需要今天就决定将来做什么。我们只需要决定今天做什么，随着我们了解更多，未来的决定可以修改。在这项研究中，我们使用随机版本的DICE-99模型（Nordhaus WD，Boyer J（2000）Warming the world：economic models of global warming.麻省理工学院出版社，剑桥，马萨诸塞州，美国），以探讨不同的学习速度对适当水平的近期政策的影响。我们发现，学习的效果强烈依赖于是否选择效率（平衡成本和效益）或成本效益（稳定在一个给定的温度变化目标）作为政策设计的标准。然后，我们通过计算贝叶斯更新的气候敏感性的后验分布来模拟内生学习，基于对于给定的真实气候敏感性将观察到的温度变化以及关于误差、先验分布和存在额外不确定性的假设。我们表明，减少气候不确定性的不确定性需要更长的时间，当也有不确定性的热量吸收率的海洋，除非使用额外的观测，如海平面上升。
Climate change is an issue of risk management. The most important causes for concern are not the median projections of future climate change, but the low-probability, high-consequence impacts. Because the policy question is one of sequential decision making under uncertainty, we need not decide today what to do in the future. We need only to decide what to do today, and future decisions can be revised as we learn more. In this study, we use a stochastic version of the DICE-99 model (Nordhaus WD, Boyer J (2000) Warming the world: economic models of global warming. MIT Press, Cambridge, MA, USA) to explore the effect of different rates of learning on the appropriate level of near-term policy. We show that the effect of learning depends strongly on whether one chooses efficiency (balancing costs and benefits) or cost-effectiveness (stabilizing at a given temperature change target) as the criterion for policy design. Then, we model endogenous learning by calculating posterior distributions of climate sensitivity from Bayesian updating, based on temperature changes that would be observed for a given true climate sensitivity and assumptions about errors, prior distributions, and the presence of additional uncertainties. We show that reducing uncertainty in climate uncertainty takes longer when there is also uncertainty in the rate of heat uptake by the ocean, unless additional observations are used, such as sea level rise.