講演情報
[ACG64-P06]Long-term Earth System Responses, Reversibility, and Tipping Points Beyond 2100: Implications for Climate Policy
*横畠 徳太1、メルニコワ イリーナ1、林 未知也1、塩竈 秀夫1、仁科 一哉1、高尾 信太郎1、渡辺 泰士1、鈴木 立郎2、草原 和弥2、羽島 知洋2、河宮 未知生2、佐藤 雄亮2、吉森 正和3、阿部 彩子3、國吉 優太3、釜江 陽一4、小林 英貴5、山本 彬友6、田中 克政7、高橋 潔1 (1.国立環境研究所、2.海洋研究開発機構、3.東京大学、4.筑波大学、5.富山大学、6.千葉大学、7.ピエールシモンラプラス研究所)
キーワード：
気候変動、地球システムモデル、ティッピングポイント、気候政策
The Earth system responds to greenhouse gas (GHG) emissions over a wide range of time scales, with many tipping elements exhibiting characteristic response times of a century or longer. Nevertheless, projections presented in the Intergovernmental Panel on Climate Change (IPCC) assessment reports, as well as in most previous climate studies, have been limited to socio-economic scenarios extending only to the year 2100. As a result, the dynamics of climate change beyond 2100 remain insufficiently explored. To address this gap, we aim to provide a clear, long-term perspective on climate change in the post-2100 period—an underexamined domain—to highlight the urgency of strong mitigation efforts.
In this study, we use the Earth system model MIROC-ES2L to conduct long-term climate projections under scenarios in which the Shared Socioeconomic Pathways (SSPs) are extended to the year 2500. In addition to these extended SSP scenarios, we design numerical experiments in which the global mean temperature is returned toward pre-stabilization levels following a period of stabilization, allowing us to investigate the reversibility of climate-induced changes.
Analysis of simulated atmospheric, oceanic, and terrestrial variables enables us to examine interactions among multiple Earth system components, including key tipping elements. Particular emphasis is placed on assessing whether large-scale transitions triggered by strong climatic perturbations are reversible or irreversible. Scenario-based comparisons further allow us to explore the long-term trajectory of unmitigated climate change and evaluate its consequences for human societies and ecosystems.
In this presentation, we also introduce a new tipping-point research initiative currently being planned in Japan. This project aims to develop future socio-economic scenarios that explicitly account for pathways toward climate stabilization, including overshoot scenarios and pathways in which mitigation measures are delayed or insufficient. Using Earth system models, we will conduct numerical experiments based on these scenarios to elucidate the mechanisms underlying Earth system responses such as tipping behavior. Finally, by synthesizing the latest scientific findings, we aim to provide an integrated understanding of long-term climate risks and to formulate actionable policy recommendations.
In this study, we use the Earth system model MIROC-ES2L to conduct long-term climate projections under scenarios in which the Shared Socioeconomic Pathways (SSPs) are extended to the year 2500. In addition to these extended SSP scenarios, we design numerical experiments in which the global mean temperature is returned toward pre-stabilization levels following a period of stabilization, allowing us to investigate the reversibility of climate-induced changes.
Analysis of simulated atmospheric, oceanic, and terrestrial variables enables us to examine interactions among multiple Earth system components, including key tipping elements. Particular emphasis is placed on assessing whether large-scale transitions triggered by strong climatic perturbations are reversible or irreversible. Scenario-based comparisons further allow us to explore the long-term trajectory of unmitigated climate change and evaluate its consequences for human societies and ecosystems.
In this presentation, we also introduce a new tipping-point research initiative currently being planned in Japan. This project aims to develop future socio-economic scenarios that explicitly account for pathways toward climate stabilization, including overshoot scenarios and pathways in which mitigation measures are delayed or insufficient. Using Earth system models, we will conduct numerical experiments based on these scenarios to elucidate the mechanisms underlying Earth system responses such as tipping behavior. Finally, by synthesizing the latest scientific findings, we aim to provide an integrated understanding of long-term climate risks and to formulate actionable policy recommendations.