Scientists at World Weather Attribution say human-driven warming did at least as much as this year’s El Niño to strengthen Hurricane Polo. The eastern Pacific storm exploded into Category 5 within a day in late September and lingered near peak strength longer than any previous Category 5 in that basin.
Teams from Mexico, the United States, Britain, Ireland and the Netherlands examined sea-surface heat and potential intensity — a blend of ocean and air measures that bounds how hard a hurricane can blow. Waters along Polo’s path sat roughly 1.4°C above a pre-industrial baseline, conditions the study calls about 200 times more likely today. Climate change made such potential-intensity settings about 23 times more probable and lifted them by around five metres per second.
El Niño still mattered: compared with a neutral year it made those intensity conditions about 14 times more likely and added roughly 4.2 metres per second. A second method put Polo’s actual peak winds about 2.7 metres per second higher than they would have been without warming. Observed rainfall extremes in the landfall belt look wetter than past decades, but models fail to reproduce that trend, so the rain signal stays qualitative.
Polo first came ashore as a Category 2 storm over thinly populated Baja California Sur, then as a Category 1 east of Guaymas. Early warnings limited the death toll, yet floods still killed people in Jalisco and Sonora, and remnants flooded parts of the US Southwest. Luck — a weaker landfall and sparse coasts — mattered as much as preparedness.
The takeaway for planners is the balance of forces. In a hot Pacific season, blaming only El Niño understates the human fingerprint. Coastal codes and evacuation drills now need to price both drivers together, not as competing excuses.
