Projections of future climate for U.S. national assessments: past, present, future
Climate assessments synthesize projected future conditions using global climate models, and over the past 30 years both the science and assessment processes have evolved. This review examines how climate projections have been used in U.S. national climate assessments, noting improvements in model structure, climate‑feedback constraints and computational capacity. As assessment audiences broaden, the framing and accessibility of projection information have become increasingly important. Key opportunities for future assessments include establishing benchmarks for evaluating downscaled datasets, expanding efforts to identify research gaps and user needs, and offering clearer practitioner guidance on interpreting projections and uncertainty. These insights support more effective use of climate projections in decision‑making.
Subject Tags
- Climate impacts
- Climate risks
Abstract
Climate assessments consolidate our understanding of possible future climate conditions as represented by climate projections, which are largely based on the output of global climate models. Over the past 30 years, the scientific insights gained from climate projections have been refined through model structural improvements, emerging constraints on climate feedbacks and increased computational efficiency. Within the same period, the process of assessing and evaluating information from climate projections has become more defined and targeted to inform users. As the size and audience of climate assessments has expanded, the framing, relevancy and accessibility of projections has become increasingly important. This paper reviews the use of climate projections in national climate assessments (NCA) while highlighting challenges and opportunities that have been identified over time. Reflections and lessons learned address the continuous process to understand the broadening assessment audience and evolving user needs. Insights for future NCA development include (1) identifying benchmarks and standards for evaluating downscaled datasets, (2) expanding efforts to gather research gaps and user needs to inform how climate projections are presented in the assessment (3) providing practitioner guidance on the use, interpretation and reporting of climate projections and uncertainty to better inform decision-making.
Citation
Basile, S., Crimmins, A., Lipschultz, F., Kunkel, K. E., Marvel, K., Terando, A., ... & Hayhoe, K. (2025). Projections of future climate for US national assessments: past, present, future. Climatic Change, 178(4), 84. https://doi.org/10.1007/s10584-025-03888-6
TNC Authors
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Katharine Hayhoe
Chief Scientist
The Nature Conservancy
Email: katharine.hayhoe@tnc.org