There is a substantial gap between the current emissions of greenhouse gases and levels required for achieving the 2°C and 1.5°C temperature targets of the Paris Agreement. Understanding the implications of a temperature overshoot is thus an increasingly relevant research topic. Here we explore the carbon cycle feedbacks over land and ocean in the SSP5‐3.4‐OS overshoot scenario by using an ensemble of Coupled Model Intercomparison Project 6 Earth system models. Models show that after the CO₂ concentration and air temperature peaks, land and ocean are decreasing carbon sinks from the 2,040s and become sources for a limited time in the 22nd century. The decrease in the carbon uptake precedes the CO₂ concentration peak. The early peak of ocean uptake stems from its dependency on the atmospheric CO₂ growth rate. The early peak of the land uptake occurs due to a larger increase in ecosystem respiration than the increase in gross primary production, as well as due to a concomitant increase in land‐use change emissions primarily attributed to the wide implementation of biofuel croplands. The carbon cycle feedback parameters amplify after the CO₂ concentration and temperature peaks due to inertia of the Earth system so that land and ocean absorb more carbon per unit change in the atmospheric CO₂ change (stronger negative feedback) and lose more carbon per unit temperature change (stronger positive feedback) compared to if the feedbacks stayed unchanged. The increased negative CO₂ feedback outperforms the increased positive climate feedback. This feature should be investigated under other scenarios.

中文翻译：

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碳循环对超过2°C的温度超调的响应：CMIP6模型的分析

当前的温室气体排放量与实现《巴黎协定》的2°C和1.5°C温度目标所需的水平之间存在很大差距。因此，了解温度超调的含义是一个越来越重要的研究主题。在这里，我们通过使用耦合模型比较项目6地球系统模型的集合，探索了SSP5-3.4-OS超调场景中陆地和海洋的碳循环反馈。模型显示，在CO ₂浓度和气温达到峰值之后，陆地和海洋正在减少2040个碳汇的碳汇，并在22世纪的有限时间内成为碳源。碳吸收的减少先于CO ₂浓度峰值。海洋吸收的早期高峰源于其对大气CO ₂增长率的依赖性。土地吸收的早期高峰是由于生态系统呼吸的增加大于初级生产总值的增加，以及由于主要由于生物燃料耕地的广泛使用而引起的土地利用变化排放量的同时增加。由于地球系统的惯性，碳循环反馈参数会在CO ₂浓度和温度达到峰值后放大，从而使陆地和海洋在大气CO _2的每单位变化中吸收更多的碳与保持不变相比，每单位温度变化（负反馈更强）变化和碳损失更多（正反馈更强）。增加的负CO ₂反馈优于增加的正气候反馈。此功能应在其他情况下进行研究。