Preprints
https://doi.org/10.5194/egusphere-2025-4660
https://doi.org/10.5194/egusphere-2025-4660
08 Oct 2025
 | 08 Oct 2025
Status: this preprint is open for discussion and under review for Geoscientific Model Development (GMD).

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

Jenny Bjordal, Anthony A. Smith Jr., Henri Cornec, and Trude Storelvmo

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.

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Jenny Bjordal, Anthony A. Smith Jr., Henri Cornec, and Trude Storelvmo

Status: open (until 03 Dec 2025)

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Jenny Bjordal, Anthony A. Smith Jr., Henri Cornec, and Trude Storelvmo

Data sets

Input data for running the model Jenny Bjordal et al. https://www.dropbox.com/scl/fo/mm9utacdrk42fmzv6juh4/AIUr4sSBMterks3Tjsd3YEU?rlkey=plm6rqom86dqasan7cf13ge0r&st=hcc7c3e3&dl=0

NorESM2-DIAM prototype simulation, coupled output Jenny Bjordal https://doi.org/10.11582/2025.90v981qk

Model code and software

NorESM2-DIAM model code and scripts for creating input files and processing output Jenny Bjordal, Henri Cornec and Tony Smith https://doi.org/10.5281/zenodo.17176879

Jenny Bjordal, Anthony A. Smith Jr., Henri Cornec, and Trude Storelvmo
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Latest update: 08 Oct 2025
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Short summary
Our research introduces NorESM2-DIAM, a new modelling tool that connects a climate model with an economic model to better understand how climate change affects economies. With the new model we can estimate both global and regional economic consequences – and shows that these impacts can vary a lot depending on where you are. The model is the first of its kind and a good starting point for future model development, making even better predictions possible in the future.
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