Abstract for: Assessing the dynamic impact of nuclear fusion on climate change

Limiting global warming to well below 2°C requires global greenhouse gas emissions to fall rapidly over the next two-and-a-half decades and reach net zero by mid‑century. Nuclear fusion has re-emerged as a technology heavily promoted as a climate solution. Here, we explore the conditions, if any, in which nuclear fusion could provide meaningful contributions to mitigate climate change in time to limit warming to well below 2°C. We use the En-ROADS climate-energy model to analyze the likely impact of fusion on the climate. We explore scenarios varying parameters including when a fusion breakthrough occurs, commercialization and construction lags, costs, and learning that may lower costs further as it scales. En ROADS captures the dynamic interactions of a potential fusion breakthrough with other energy sources, prices, and demand, and the resulting impacts on GHG emissions and the climate. Results suggest the climate benefits of a major breakthrough in fusion are likely to be small. First, the delays in scale up to global impact remain long, even under optimistic conditions including a breakthrough before 2030, short commercialization delays, and low costs. Second, the rapid growth of renewables (wind, solar, etc.) means that fusion will not only displace fossil sources but cannibalize other low and zero emissions technologies. We provide the first system dynamics-based assessment of fusion’s potential impact on climate, focusing on timing, scale, and interactions with other power sources. Even if fusion becomes a viable, low-cost energy source, delays in scale-up and cannibalization of other low emissions technologies limit its climate impact. Our analysis aims to clarify expectations for fusion within global climate strategies and inform policymakers, investors, and the broader public. Search for non-scientific sources