IPCC AR6报告解读：未来的全球气候——基于情景的预估和近期信息

依据IPCC第六次评估报告（AR6）第一工作组报告第四章的内容,对未来全球气候的预估结果进行解读。报告对21世纪全球表面气温、降水、大尺度环流和变率模态、冰冻圈和海洋圈的可能变化进行了系统评估,并对2100年以后的气候变化做了合理估计。评估指出全球平均表面气温将在未来20年内达到或超过1.5℃,平均降水也将增加,但随季节和区域而异,同时变率将增大。大尺度环流和变率模态受内部变率影响较大。到21世纪末,北冰洋可能出现无冰期;全球海洋会继续酸化,平均海平面将持续上升,百年内上升幅度依赖不同排放情景,都在2100年后继续升高。在最新的评估中采用多种约束方法,减小了预估不确定性的范围。AR6对于低排放情景以及“小概率高增暖情节”的关注为应对气候变化提供了更多、更完整的信息。综合报告的评估结果指出,未来需要进一步减小区域,特别是季风区气候预估的不确定性,并从科学研究和模式发展两方面加强我国气候预估能力的建设。

Interpreting IPCC AR6: future global climate based on projection under scenarios and on near-term information

Based on the content of Chapter 4 from the Sixth Assessment Report (AR6) contributed by the IPCC Working Group I, we interpret the future projections of global climate change. The AR6 systematically assessed possible changes of global surface air temperature, precipitation, large-scale circulation and modes of variability, and changes in ocean and cryosphere, and further reasonably estimated the climate change beyond 2100. The assessments show that global mean surface air temperature would reach 1.5℃ or even beyond it. Mean-state and variability of precipitation would increase as well, but varying with seasons and regions. Large-scale circulation and modes of variability are more affected by internal variability rather than external forcing. By the end of the 21st century, ice-free period would be seen in the Arctic. Ocean acidification and increase of global mean sea level (GMSL) would continue at the century time scale with uncertain magnitudes depending on emission scenarios. The projected GMSL would go higher beyond 2100 under all the scenarios. Multiple constraining methods are introduced in this latest assessment, reducing the uncertainty range of future projection. By paying an additional attention to the low emission scenarios and low-likelihood high-impact storylines, the AR6 provided richer and more comprehensive information for addressing climate change. Integrating the assessment conclusions, we suggest that future studies need to reduce the projected uncertainties in regional climate change, especially in the monsoon regions, and that capability construction of climate projection in China need to be strengthened in both scientific research and model development.