Forecasters say this year's El Niño may reach its strongest level in a century. The Met Office projects the natural warming of sea temperatures will exceed 3 degrees in coming months, describing it as potentially the largest such event since the 19th century.

The anomaly in numbers

Global sea surface temperatures in July ran 2.1 degrees Celsius above the long-term average, surpassing the record set during the 2023 marine heat wave. NOAA's relative Niño index forecast mean of 2.66, if it verifies, would rank as the strongest in the observational record.

El Niño is the warming of equatorial Pacific sea surface temperatures above normal, and it redistributes rainfall globally — drought concentrating in one region while another takes heavy rain.

The Panama Canal reacted first

The most concrete effect has appeared at the Panama Canal. The authority said daily transits will be capped at 34 vessels from Sept. 4 and cut further to 32 from Sept. 15. Rainfall in the watershed from May to August was 34 percent below the historical average, with inflows 44 percent below normal.

Because the canal's locks run on fresh water stored in artificial lakes, a rainfall shortfall translates directly into reduced transit capacity. Restrictions show up as longer waits and higher freight rates, and push some carriers to weigh routing around the Cape of Good Hope.

For Korean and Taiwanese shippers using Asia-to-US-East-Coast routes, this is an upward force on year-end peak-season logistics costs. Combined with uncertainty in the Strait of Hormuz, it leaves two major maritime chokepoints under pressure at the same time.