Jenny Bjordal

• Bjordal, Jenny; Smith, Anthony A.; Cornec, Henri & Storelvmo, Trude (2026). NorESM2–DIAM: a coupled model for investigating global and regional climate-economy interactions. Geoscientific Model Development. ISSN 1991-959X. 19(3), p. 1337–1365. doi: 10.5194/gmd-19-1337-2026. Full text in Research Archive
• Bjordal, Jenny; Storelvmo, Trude & Jr., Anthony A Smith (2022). Quantifying uncertainty about global and regional economic impacts of climate change. Environmental Research Letters. 17(9). doi: 10.1088/1748-9326/ac8ab1. Full text in Research Archive Show summary

  Abstract The economic impacts of climate change are highly uncertain. Two of the most important uncertainties are the sensitivity of the climate system and the so-called damage functions, which relate climate change to economic costs and benefits. Despite broad awareness of these uncertainties, it is unclear which of them is most important, especially at the regional level. Here we construct regional damage functions, based on two different global damage functions, and apply them to two climate models with vastly different climate sensitivities. We find that uncertainty in both climate sensitivity and aggregate economic damages per degree of warming are of similar importance for the global economic impact of climate change, with the decrease in global economic productivity ranging between 4% and 24% by the end of the century under a high-emission scenario. At the regional level, however, the effects of climate change can vary even more substantially, depending both on a region’s initial temperature and the amount of warming it experiences, with some regions gaining in productivity and others losing. The ranges of uncertainty are therefore potentially much larger at a regional level. For example, at the end of the century, under a high-emission scenario, we find that India’s productivity decreases between 13% and 57% and Russia’s increases between 24% and 74%, while Germany’s change in productivity ranges from an increase of 8% to a decrease of 4%. Our findings emphasise the importance of including these uncertainties in estimates of future economic impacts, as they are vital for the resulting impacts and thus policy implications.

• Bjordal, Jenny; Storelvmo, Trude; Alterskjær, Kari & Carlsen, Tim (2020). Equilibrium climate sensitivity above 5 °C plausible due to state-dependent cloud feedback. Nature Geoscience. ISSN 1752-0894. 13, p. 718–721. doi: 10.1038/s41561-020-00649-1. Full text in Research Archive Show summary

  The equilibrium climate sensitivity of Earth is defined as the global mean surface air temperature increase that follows a doubling of atmospheric carbon dioxide. For decades, global climate models have predicted it as between approximately 2 and 4.5 °C. However, a large subset of models participating in the 6th Coupled Model Intercomparison Project predict values exceeding 5 °C. The difference has been attributed to the radiative effects of clouds, which are better captured in these models, but the underlying physical mechanism and thus how realistic such high climate sensitivities are remain unclear. Here we analyse Community Earth System Model simulations and find that, as the climate warms, the progressive reduction of ice content in clouds relative to liquid leads to increased reflectivity and a negative feedback that restrains climate warming, in particular over the Southern Ocean. However, once the clouds are predominantly liquid, this negative feedback vanishes. Thereafter, other positive cloud feedback mechanisms dominate, leading to a transition to a high-sensitivity climate state. Although the exact timing and magnitude of the transition may be model dependent, our findings suggest that the state dependence of the cloud-phase feedbacks is a crucial factor in the evolution of Earth’s climate sensitivity with warming.

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• Bjordal, Jenny; Jr., Anthony A. Smith,; Cornec, Henri & Storelvmo, Trude (2026). NorESM2-DIAM: a new coupled climate-economy model for understanding the regional economic impacts of climate change. Full text in Research Archive Show summary

  Climate change poses substantial risks to economies worldwide, yet quantifying these impacts and their regional distribution remains a major challenge. Here we present NorESM2-DIAM, a new modelling framework that—to our knowledge—is the first to fully couple an Earth system model with a high-resolution cost-benefit integrated assessment model. Most modelling frameworks either lack two-way climate-economy interactions or operate at coarse spatial scales, limiting our ability to understand who is affected by climate change, where, and by how much. NorESM2-DIAM links the Norwegian Earth System Model version 2(NorESM2) with the Disaggregated Integrated Assessment Model (DIAM). DIAM represents the global economy across approximately 19,000 regions on a 1°×1° grid, and temperature and CO₂ emissions are exchanged annually at each grid cell. Because the coupling is two-way, the model generates its own emissions pathway rather than relying on prescribed scenarios. A baseline simulation shows large regional differences in climate damages, with the highest impacts in already-hot, low-latitude regions, while the coldest regions actually benefit. The results also show that internal climate variability generates substantial volatility in regional GDP, suggesting that short-term changes—not just long-term trends—matter for economic outcomes. Our results underline the importance of high-resolution, two-way coupled models for understanding the regional economic impacts of climate change and their policy implications.

• Bjordal, Jenny; Storelvmo, Trude; Jr., Anthony A. Smith, & Pedersen, Pål Andreas (2026). The Climate Casino: Teaching Climate Change and Mitigation Through Play. Full text in Research Archive Show summary

  Climate change is a complex problem that spans multiple disciplines, including natural science, socioeconomics, ethics, and politics. This complexity makes it challenging to make well-informed decisions about climate change. We therefore introduce The Climate Casino, an educational game that offers a fun and engaging way to learn about climate change and mitigation. At the start of the game, participants are divided into groups representing different geographic regions. They are given two goals: a primary, shared goal to keep global warming below 1.5°C and a secondary, competitive goal to maximise their own region’s economic development. These competing goals create a tricky balance between cooperation and self-interest, introducing challenges such as the free-riding problem. The groups’ assigned regions differ in economic and climatic conditions, and are responsible for various amounts of greenhouse gas emissions—reflecting real-world inequalities. Each group makes decisions for its region by setting a carbon tax. Higher carbon taxes increase production costs, leading to reduced economic output and, consequently, lower emissions. Thus, the carbon tax influences the economy through two competing mechanisms: reduced productivity, which negatively impacts economic output, and reduced climate change, which can have positive or negative economic effects depending on the region. The consequences of the participants’ decisions are calculated using the coupled climate–economy model NorESM2-DIAM, which provides both climatic and economic outcomes. While necessarily simplified, this approach introduces participants to key concepts in climate modelling and highlights the role of uncertainty and regional differences in climate–economy interactions. Through surveys before and after playing the game, we see that participants change how they think about climate change and mitigation. This demonstrates the potential of The Climate Casino as an engaging educational tool that can promote greater climate literacy.

• Bjordal, Jenny; Dijk, Evelien Van; Cornec, Henri; Jr., Anthony A. Smith, & Storelvmo, Trude (2026). Can Solar Radiation Management Reduce Economic Inequality? Insights from a Coupled Climate–Economy Model. doi: 10.5194/egusphere-egu26-3980. Full text in Research Archive Show summary

  As the world struggles to limit emissions, Solar Radiation Management (SRM) has been proposed as a potential climate intervention. However, its implications for economic inequality and broader socioeconomic outcomes remain uncertain. To explore these questions, we used the coupled climate-economy model NorESM2-DIAM to simulate an idealised SRM experiment. NorESM2 is an Earth system model, while DIAM is a cost-benefit integrated assessment model using perfect foresight. The two models exchange temperature and CO2 emissions annually at a 1x1-degree resolution: temperatures from NorESM2 are passed to DIAM, where they affect economic productivity and the economic agents’ decisions. In DIAM, the agents make decisions about savings and energy use based on temperature, the current economic situation, and their expectations for the future. The resulting CO2 emissions are passed back to NorESM2.In the experiment, we reduced solar insolation by 1% from 2030 onward, at which point the economic agents adjusted their expectations to account for SRM. The results suggest that SRM reduces economic inequality compared to no intervention. However, this outcome is accompanied by higher CO₂ emissions, which imply additional environmental and societal risks.While this is an idealised experiment, it demonstrates potential trade-offs between geoengineering and socioeconomic outcomes. The high spatial resolution of the model offers future potential to assess regional inequalities and other distributional outcomes in greater detail. In addition, we plan to explore more realistic SRM scenarios and add additional climate–economy interactions.

• Bjordal, Jenny; Storelvmo, Trude & Jr, Anthony A. Smith, (2022). The climate casino: Winners and losers in a warmer world. Full text in Research Archive
• Bjordal, Jenny; Storelvmo, Trude & Jr, Anthony A. Smith, (2022). The climate casino: Winners and losers in a warmer world. Full text in Research Archive
• Bjordal, Jenny; Storelvmo, Trude & Jr, Anthony A. Smith, (2021). Economic winners and losers in a warmer world - Uncertainties in regional economic impacts of climate change. Full text in Research Archive
• Bjordal, Jenny; Storelvmo, Trude & Jr, Anthony A. Smith, (2019). Climate change modelling and prediction of economic impact. Full text in Research Archive
• Bjordal, Jenny; Storelvmo, Trude & Jr, Anthony A. Smith, (2019). Climate change modelling and prediction of economic impact. Full text in Research Archive
• Bjordal, Jenny (2017). Sample Seismic from PCube Prior Model - Report after summer internship. Norsk Regnesentral. Full text in Research Archive

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