[A-CG34] Projection and detection of global environmental change

[ACG34-P04] Advanced studies of climate change projection – Area Theme 2: Biogeochemical modeling and climate simulations for carbon budget assessment

*Michio Kawamiya¹, Tomohiro Hajima¹, Junichi Tsutsui², Hiroaki Tatebe¹, Kaoru Tachiiri¹, Tokuta Yokohata³, Kazuhisa Tanada⁴ (1.Japan Agency for Marine-Earth Science and Technology, 2.Central Research Institute of Electric Power Industry, 3.National Institute for Environmental Studies, 4.Japan Aerospace Exploration Agency)

Keywords:Climate change, Earth system, Carbon budget, IPCC

The Advanced Studies of Climate Change Projection, or SENTAN (abbreviation taken from its Japanese name), is a national project for climate change projection launched in June 2022. The program aims to improve our understanding of climate change mechanisms, reduce uncertainties, and create highly accurate projections that can be used as the scientific basis for developing climate change adaptation and mitigation measures. While the entire program deals with a wide range of natural scientific aspects and consequences of climate change, Area Theme 2 focuses on the development of a state-of-the-art Earth system model (ESM) incorporating biogeochemical processes with a particular emphasis on contributing to mitigation policy, such as elaborate evaluation of the remaining carbon budget. Also in perspective is an exploration of interactions between climate change and human socio-economics.

Prominent results obtained so far include “global eutrophication” showing that anthropogenic nutrient input into the ocean via aerosol and rivers can have a significant positive impact on oceanic primary production, which is comparable in magnitude to the negative impact of strengthened stratification due to warming. Another noteworthy effort is the modeling of wildfires, which is important in terms of both climate change impact assessment and understanding the carbon cycle. Artificial intelligence is adopted to link environmental variables such as soil wetness and temperature and those describing wildfires, such as burned areas and carbon emissions. Trial experiments using past data exhibit that the model has reasonable capability for projecting wildfire occurrence. Furthermore, to advance our understanding of the interactions between society and climate change, we will quantify the carbon budget and explore corresponding emission reduction pathways using a model suite including a climate model emulator and an ESM combined with a socioeconomic model. We will also focus on outreach. We hope that the research findings can be used as a scientific basis for planning measures against climate change through, e.g., contributions to IPCC’s next assessment reports.