Overview

• The PNAS analysis finds the seasonal upwelling largely collapsed in early 2025, marking the first near-complete failure in the observational record.
• Cooling that typically begins in late January was delayed until March, lasted about 12 days instead of roughly 66, and bottomed out near 23–23.3 °C rather than the usual ~19 °C.
• Researchers report north-wind occurrences were about 74% less frequent despite normal wind speeds, limiting offshore transport of surface water and suppressing deep-water rise.
• A weak La Niña was present but is deemed insufficient to explain the event on its own, and investigators say the mechanisms remain unresolved.
• Field accounts describe fishing activity largely halted as trawlers stayed in port, and the team urges intensified observations and modeling to determine whether this was an anomaly or an emerging pattern.