9:55 AM - 10:10 AM
[ACG34-04] Long-term responses and tipping elements in Earth system beyond 2100
Keywords:Earth System Model, Tipping Elements
Since the Paris Agreement, climate mitigation efforts have been progressing. Global greenhouse gas emissions (GHGs) are increasing, but the rate of increase has slowed compared to the 2010s. Under the Paris Agreement, countries around the world have declared Nationally Determined Contributions (NDCs), and there are projections that if all the declared contents are realized, the 2-degree target will be achieved. However, when considering the feasibility of achieving the NDC declared by each country, the path to achieving the goal is not necessarily easy, as laws and policies to achieve net zero are not actually in place. Considering the reliability of whether countries around the world can realize their NDCs, some estimates suggest that it will be difficult to achieve net zero in the 21st century. Therefore, if net-zero emissions are not achieved during the 21st century, climate change may continue into the 21st century and beyond.
The responses of the Earth system to GHG emissions have various characteristics and time scales, and the time scales of the responses become longer when the effects extend to the deep ocean or land surface. Among these responses the tipping elements are attracting attention as an element that has a large impact on human society. Tipping elements that can cause irreversible changes involve responses over a wide range of time scales, with most having time scales of 100 years or more. For this reason, it is extremely important to consider climate change that will occur after 2100.
However, IPCC assessment reports and previous climate change studies have analyzed future projections based on socio-economic scenarios up to 2100, and climate change after 2100 has rarely been investigated. Given the possibility that climate change will continue beyond the 21st century and that the Earth system will exceed a tipping point, it is extremely important to analyze changes in the climate and Earth system after 2100 and assess their impact on human society and ecosystems. Previous studies on climate change over 2100 years have included analyzes using 0-dimensional simplified models based on expert judgment and analyzes using simple climate models. However, research using earth system models (ESMs) that consider complicated processes among the atmosphere, land and ocean has not been done.
Therefore, in this study, we analyze long-term changes in the Earth system using an ESM MIROC-ES2L (Hajima et al. 2020, Geoscience Model Development). Here, we performed future projection experiments using a scenario that extends the Shared Socio-Economic Pathways (SSP) to the year 2500. The scenarios include a low-emissions scenario in which net-zero emissions are achieved during the 21st century (SSP119/126/434), and a medium-emissions scenario in which mitigation progress in the 21st century but net-zero emissions are not achieved (SSP245/460), a high-emissions scenario (SSP370/585) in which emissions continue to increase, and an overshoot scenario (SSP534os) in which temperatures rise once and achieve the 2-degree target. By analyzing the obtained experimental results for various elements in the atmosphere, ocean, and land, we investigated interactions among various elements in the Earth system, including tipping elements. In addition, by comparing scenarios, we investigated long-term climate change without climate mitigation and discuss its impact on human society and ecosystems. Our major goal is to convey to society the importance of climate mitigation measures by presenting overall picture about climate change beyond 2100, which has not been sufficiently demonstrated to date.
The responses of the Earth system to GHG emissions have various characteristics and time scales, and the time scales of the responses become longer when the effects extend to the deep ocean or land surface. Among these responses the tipping elements are attracting attention as an element that has a large impact on human society. Tipping elements that can cause irreversible changes involve responses over a wide range of time scales, with most having time scales of 100 years or more. For this reason, it is extremely important to consider climate change that will occur after 2100.
However, IPCC assessment reports and previous climate change studies have analyzed future projections based on socio-economic scenarios up to 2100, and climate change after 2100 has rarely been investigated. Given the possibility that climate change will continue beyond the 21st century and that the Earth system will exceed a tipping point, it is extremely important to analyze changes in the climate and Earth system after 2100 and assess their impact on human society and ecosystems. Previous studies on climate change over 2100 years have included analyzes using 0-dimensional simplified models based on expert judgment and analyzes using simple climate models. However, research using earth system models (ESMs) that consider complicated processes among the atmosphere, land and ocean has not been done.
Therefore, in this study, we analyze long-term changes in the Earth system using an ESM MIROC-ES2L (Hajima et al. 2020, Geoscience Model Development). Here, we performed future projection experiments using a scenario that extends the Shared Socio-Economic Pathways (SSP) to the year 2500. The scenarios include a low-emissions scenario in which net-zero emissions are achieved during the 21st century (SSP119/126/434), and a medium-emissions scenario in which mitigation progress in the 21st century but net-zero emissions are not achieved (SSP245/460), a high-emissions scenario (SSP370/585) in which emissions continue to increase, and an overshoot scenario (SSP534os) in which temperatures rise once and achieve the 2-degree target. By analyzing the obtained experimental results for various elements in the atmosphere, ocean, and land, we investigated interactions among various elements in the Earth system, including tipping elements. In addition, by comparing scenarios, we investigated long-term climate change without climate mitigation and discuss its impact on human society and ecosystems. Our major goal is to convey to society the importance of climate mitigation measures by presenting overall picture about climate change beyond 2100, which has not been sufficiently demonstrated to date.