Keynote at CMIP 2026 - Confronting Earth System Model trends with observations

A during the CMIP Community Workshop 2026, held in Kyoto, Japan in March 2026. Isla Simpson, NCAR, presented on the topic 'Confronting Earth System Model trends with observations'. Anthropogenically forced trends in the Earth System have now been unfolding for decades. At the same time, the Coupled Model Intercomparison Project has offered the opportunity to compare this evolving reality with that predicted by Earth System Models. It has allowed us to gain understanding of the origins of observed changes, as well as to predict how these changes will be expected to evolve in the future. With three major CMIP phases completed over the span of nearly 20 years and a fourth now underway and the growing forced signal that is emerging from the noise in many areas of the Earth System, it is an important time to confront long-term trends in Earth System Models with observations. CMIP has played an important role in allowing the research community to evaluate models in their ability to reproduce long-term trends, to identify where they succeed, where they don't and where improved understanding is needed. This presentation will review the current state of understanding of the ability of Earth System Models to capture historical trends and will highlight key uncertainties, emerging issues, and progress to be made as we look ahead to CMIP7.