Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Geophysical Research Letters
The Pacific Decadal Oscillation (PDO) is a slowly evolving pattern of ocean temperature anomalies in the North Pacific that can influence climate and ecosystems across the globe. The climate science community and stakeholders are increasingly interested in how well we can predict the PDO from months to years in advance, but such predictions are not equally reliable at all times of year. As the PDO is part of a coupled ocean-atmosphere system, such simulations are very resource intensive.
Meeker et al. [2025] use the Seasonal to Multi Year Large Ensemble (SMYLE)—a large ensemble of initialized decadal hindcast simulations with the fully coupled Community Earth System Model 2 (CESM2)—to show that while the PDO is predictable up to one year in advance, skill drops off most rapidly during late fall and spring, a seasonal pattern that mirrors known challenges in forecasting El Niño events in the tropical Pacific. Using a simple statistical model, the authors further show that much of the PDO’s predictability comes from persistence—the ocean’s tendency to stay in the same state for a while—but atmospheric teleconnections from the tropical Pacific also play an important role.
The results highlight that when El Niño is hard to predict, so is the PDO. Understanding when and why these prediction skill drops happen is important for improving seasonal forecasts that support fisheries, agriculture and water management. This work also shows how relatively simple linear models can help diagnose behavior in more complex models of the coupled climate system, enabling benchmarking and improvement of more advanced forecasting systems.
Citation: Meeker, E. D., Maroon, E. A., Deppenmeier, A. L., Thompson, L. A., Vimont, D. J., & Yeager, S. G. (2025). Seasonality of pacific decadal oscillation prediction skill. Geophysical Research Letters, 52, e2025GL116122. https://doi.org/10.1029/2025GL116122
—Kristopher B. Karnauskas, Editor-in-Chief, Geophysical Research Letters