Bridging climate science and adaptation: A perspective on the construction of national climate scenarios

In many countries, National Climate Scenarios or Projections have become foundational components of national climate services, providing authoritative, science-based, locally tailored information to support climate-sensitive planning and policy. Drawing on the experiences of ten countries, this paper synthesizes current practices and identifies shared challenges in developing scientifically credible and decision-relevant climate information. Despite substantial progress, gaps persist between what users request and what climate scientists can deliver, reflecting limits in observations, models, methods, capacity, and the inherent uncertainties of weather and future climate change. Developments in climate science, including advances in (global) convection-permitting modelling, artificial intelligence and machine learning-based methods, and new generations of CMIP/CORDEX, together with expanding societal expectations, create both opportunities and dilemmas for updating and maintaining scenario products at a national scale. We highlight five outstanding questions: how to co-develop useful and credible products with diverse users; how to represent and communicate uncertainty at the science–policy interface; how to combine multiple lines of evidence across models, scales, and methods; how to integrate information on extreme events and low-likelihood, high-impact climate outcomes; and where national approaches should converge or remain nation-specific. Addressing these questions requires progress in, and collaboration between, physical climate science, the emerging science of climate services, and the social sciences. By strengthening user engagement, refining approaches to uncertainty, and expanding international collaboration to reduce duplication and raise standards, future National Climate Scenario services can provide a stronger foundation for climate information, risk assessment, adaptation planning, and associated policy processes.