When sea water, or any liquid, gets warmer, it expands. It’s the main reason that climate change has been raising sea levels, along with glaciers melting.
The expected arrival of a strong, if not record-breaking, El Niño later in 2026 could further boost sea levels temporarily by heating up much of the Pacific Ocean.
Oceanographer Ian Miller with Washington Sea Grant at the University of Washington said strong El Niños in 1982 and 1997 raised sea level on the Pacific Northwest coast by almost one foot, while another big El Niño in 2015 raised it about 6 inches.
An El Niño in the winter of 2023-24 added six to eight days of high-tide flooding on the Oregon and Washington coasts and two to four days on Puget Sound, according to the U.S. Department of Agriculture’s Northwest Climate Hub.
National Oceanographic and Atmospheric Administration researchers say there’s an 80% chance of a very strong El Niño weather pattern by autumn.
Most global climate models, operated by scientists at different institutions, are forecasting an El Niño of unprecedented strength.
“The vast majority of models, about 90% of the runs now, expect a record-setting El Niño event, stronger than anything that we have observed since records began in the mid-1800s,” Berkeley Earth climate scientist Zeke Hausfather said.