NorESM2–DIAM: A coupled model for investigating global and regional climate-economy interactions

Abstract. Global warming poses substantial risks to natural and human systems worldwide. Understanding the complex interactions between climate change and the economy is essential for designing effective policies and mitigation strategies. Yet, existing modeling tools are often limited by coarse spatial aggregation, simplified climate representation, or lack of interaction between climate and the economy. To address these gaps, we develop a novel framework that couples an Earth System Model (ESM) – the Norwegian Earth System Model version 2 (NorESM2) – with a spatially disaggregated Integrated Assessment Model (IAM), the Disaggregated Integrated Assessment Model (DIAM). The resulting modeling tool, NorESM2-DIAM, incorporates state-of-the-art climate and weather dynamics, allows economic impacts to depend on the full distribution of weather outcomes, and captures realistic spatial heterogeneity. To our knowledge, it is the first framework to fully couple an ESM with a high-resolution IAM. The primary contribution of this paper is to develop and implement the methodology that enables this coupling. We demonstrate the utility of NorESM2–DIAM through a baseline simulation. The results show that the economic impacts of global warming vary dramatically across space and that internal climate variability generates substantial volatility in regional GDP, highlighting the importance of high-resolution economic impact assessments. Although the baseline simulation focuses on regional temperature, the framework can be easily extended to incorporate additional variables such as precipitation and extreme events. It can also be applied to study a wide range of climate policies. NorESM2-DIAM represents an important step towards improving the understanding of economic impacts of climate change and can ultimately become an important source of information for decision-makers.