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A powerful ocean phenomenon is bearing down on California's coast, and scientists warn it could raise sea levels by up to a foot — worsening flood risks for coastal communities already on edge heading into what could be a historically dangerous winter.
A large mass of warm water, known as a Kelvin wave, is moving northward along the coast of Central America toward Southern California and is expected to arrive around Wednesday (October 1), according to coastal scientists tracking the system. Unlike the waves you see at the beach, Kelvin waves are massive bodies of warm water that span thousands of miles. They are not easy to spot with the naked eye in open water, but when they push up against a coastline, they can drive sea levels up by six to 18 inches over a wide area.
The wave first traveled eastward along the equator before hitting Central and South America. The landmass forced it north, and now it's heading straight for the California coast. Scientists say multiple Kelvin waves could follow in sequence, stacking up against the coast and raising sea levels even further over the coming months.
Timu Gallien, an environmental engineering professor at UCLA who studies coastal erosion, described the threat in plain terms. "Boy, if you have enough water level to support those waves so they dump right on your coast, they're right there," Gallien said. "Now they're coming through your window, now they're on your front porch, quite literally, for the beachfront homes."