关键词: 国家自主贡献, 1.5 ℃升温控制目标, 全球合作减排方案, 集成评估模型, 帕累托改进

Abstract:

The Paris Agreement recommended efforts to limit the temperature increase to 1.5℃ above pre-industrial levels. However, the current intended nationally determined contributions (INDCs) fall short of 2 ℃ scenarios, and the post-INDC period will bring severe challenges. This study details the 1.5 ℃ warming in terms of two types of restrictions. The first restriction conforms with the requirement of the Paris Agreement and requires an overall 1.5 ℃ warming restriction throughout the simulation. In the second restriction, the terminal 1.5 ℃ control relaxes the temperature restriction during the simulation and requires a 1.5 ℃ warming restriction only at the end of the simulation. Using the two restrictions, this study proposes three global cooperating abatement schemes according to different principles. Next, the study assesses the climatic effectiveness and economic feasibility of these three schemes using CIECIA, an economic-climatic integrated assessment model. The results indicate that the carbon emissions of countries should be net zero immediately following the INDC target year to meet the overall 1.5 ℃ goal in Scheme 1, and countries suffer great economic losses at the beginning of post-INDC period. In Scheme 2, the terminal 1.5 ℃ restriction allows a buffer period from INDC target years to the net zero emission period that starts in 2041. Throughout this period, approximately 52 GtC of carbon emissions are permitted. In this scheme, the economic shock around 2030 is less significant. However, by 2100 the countries suffer more cumulative utility losses than those in Scheme 1 due to warmer global temperatures during the late period. Of the three schemes, the Pareto improvement scheme permits looser carbon limits for Russia, and the high development countries (HDC) suffer more in the other schemes for industrial and geographic reasons. This scheme meets both the terminal 1.5 ℃ target and the Pareto improvement in the economies of all countries participating in global carbon abatement. Thus, it is economically feasible and climatically effective. Scheme 3 shows a link between the economies of China and the United States during carbon abatement, but it also shows that these countries are in competition with Russia and the HDC. Therefore, China could strengthen its abatement cooperation with the United States and pay attention to balance its gains with the gains of Russia and the HDC.

Key words: intended nationally determined contribution (INDC), 1.5 ℃ warming limitation, global cooperating abatement scheme, integrated assessment model, Pareto improvement