Liu Peiran R, Raftery Adrian E
Department of Statistics, University of Washington, Box 354322, Seattle, WA 98195-4322.
Commun Earth Environ. 2021;2. doi: 10.1038/s43247-021-00097-8. Epub 2021 Feb 9.
The 2015 Paris Agreement aims to keep global warming by 2100 to below 2°C, with 1.5°C as a target. To that end, countries agreed to reduce their emissions by nationally determined contributions (NDCs). Using a fully statistically based probabilistic framework, we find that the probabilities of meeting their nationally determined contributions for the largest emitters are low, e.g. 2% for the USA and 16% for China. On current trends, the probability of staying below 2°C of warming is only 5%, but if all countries meet their nationally determined contributions and continue to reduce emissions at the same rate after 2030, it rises to 26%. If the USA alone does not meet its nationally determined contribution, it declines to 18%. To have an even chance of staying below 2°C, the average rate of decline in emissions would need to increase from the 1% per year needed to meet the nationally determined contributions, to 1.8% per year.
《2015年巴黎协定》旨在到2100年将全球变暖控制在2°C以下，并将1.5°C作为目标。为此，各国同意通过国家自主贡献（NDC）来减少排放。通过使用一个完全基于统计的概率框架，我们发现，最大排放国实现其国家自主贡献的概率很低，例如美国为2%，中国为16%。按照当前趋势，将升温控制在2°C以下的概率仅为5%，但如果所有国家都实现其国家自主贡献，并在2030年后继续以相同速度减排，该概率将升至26%。如果仅美国未实现其国家自主贡献，该概率将降至18%。为了有50%的机会将升温控制在2°C以下，排放的平均下降速度需要从实现国家自主贡献所需的每年1%提高到每年1.8%。
