Columbia University School of International and Public Affairs, New York, NY, USA.
The Earth Institute at Columbia University, New York, NY, USA.
Nat Commun. 2021 Jul 29;12(1):4467. doi: 10.1038/s41467-021-24487-w.
Many studies project that climate change can cause a significant number of excess deaths. Yet, in integrated assessment models (IAMs) that determine the social cost of carbon (SCC) and prescribe optimal climate policy, human mortality impacts are limited and not updated to the latest scientific understanding. This study extends the DICE-2016 IAM to explicitly include temperature-related mortality impacts by estimating a climate-mortality damage function. We introduce a metric, the mortality cost of carbon (MCC), that estimates the number of deaths caused by the emissions of one additional metric ton of CO2. In the baseline emissions scenario, the 2020 MCC is 2.26 × 10 [low to high estimate -1.71× 10 to 6.78 × 10] excess deaths per metric ton of 2020 emissions. This implies that adding 4,434 metric tons of carbon dioxide in 2020-equivalent to the lifetime emissions of 3.5 average Americans-causes one excess death globally in expectation between 2020-2100. Incorporating mortality costs increases the 2020 SCC from $37 to $258 [-$69 to $545] per metric ton in the baseline emissions scenario. Optimal climate policy changes from gradual emissions reductions starting in 2050 to full decarbonization by 2050 when mortality is considered.
许多研究预计，气候变化可能导致大量的额外死亡。然而，在确定碳的社会成本（SCC）并规定最优气候政策的综合评估模型（IAM）中，人类死亡率的影响是有限的，且没有根据最新的科学认识进行更新。本研究通过估计气候-死亡率损害函数，将 DICE-2016 IAM 扩展到明确包括与温度相关的死亡率影响。我们引入了一个指标，即碳死亡率成本（MCC），用于估计每排放一额外吨二氧化碳所导致的死亡人数。在基准排放情景下，2020 年的 MCC 为每排放一吨 2020 年排放的二氧化碳，预计会导致 2.26×10 [低至高估计值 1.71×10 至 6.78×10]例额外死亡。这意味着在 2020 年排放相当于 3.5 个美国人的一生排放量的 4434 吨二氧化碳，会导致全球在 2020-2100 年期间预期每例额外死亡。考虑到死亡率成本后，基准排放情景下的 2020 年 SCC 从每吨 37 美元增加到 258 美元 [$69 至 545 美元]。当考虑到死亡率时，最优气候政策从 2050 年开始逐步减少排放转变为 2050 年实现完全脱碳。
