Climate models are essential tools for projecting future climate change, but they do not perfectly reproduce the present-day climate. A new study focuses on one such imperfection: biases in sea surface temperatures across the North Pacific. These biases, the researchers find, have a direct and consistent effect on the atmospheric circulation above.
The study shows that when the modeled ocean surface is warmer or cooler than observed in certain parts of the North Pacific, the model's jet stream shifts southward. This displacement is not a minor detail—the jet stream steers weather systems and influences storm tracks, precipitation, and temperature patterns across North America and the Pacific region.
The authors argue that reducing these sea surface temperature biases should be a priority for model developers. Because the bias systematically distorts the jet stream's position, it likely skews regional climate projections even as global averages look reasonable. The findings highlight how small ocean temperature errors can ripple through the atmosphere and compromise the credibility of simulated future conditions.