Exploring Global Regional Emission Pathways and Economic Impacts of Climate Change Using a Human–Earth System Coupled Model (H_R-ESM)

An updated regional integrated assessment model, RICE2025, is coupled with the Earth system model CESM2.1.5 to construct a human–Earth system coupled model (H_R2025-ESM). The simulation results are compared with those based on the earlier RICE2010 version, and regional carbon mitigation pathways as well as the economic losses associated with climate change are evaluated at the global scale. Using the H_R-ESM framework, potential changes in carbon emissions and future climate-related damages are analyzed globally and across 12 regions under different mitigation scenarios. The results indicate that H_R2025-ESM improves the accuracy of historical temperature simulations (RMSE reduced from 0.39 to 0.28), reduces global emissions by approximately 5.2 Gt(CO₂) around 2040, and leads to a decrease in global warming of about 0.2–0.3°C by the end of the century. In addition, it significantly lowers climate change–induced economic losses, with more pronounced reductions observed in developing regions.