fjo3 shares a report from The Guardian: Communities across California are rushing to prepare for the imminent arrival of the so-called "Kelvin wave," a massive underwater band of warm water threatening to inundate swaths of the vast North American shoreline. The wave is nearing southern California and expected to reach the San Francisco Bay Area by early October, as it crawls toward Alaska. Waters could rise by a foot along the California coast, according to scientists, who have warned that this could dramatically double the 8-12in rise in sea levels already caused by climate change over the last century.

The Kelvin wave doesn't climb and crash like a typical ocean wave; rather, it swells the tides from beneath the surface. It's effectively a massive slosh of warm water, driven by El Nino conditions, that moves across the Pacific before colliding with the South American coastline and surging north. It also won't transport water in the way a tsunami might, but creates conditions that enable higher sea levels to linger. On their own, Kelvin waves aren't always hazardous, according to Mike Jacox, a research oceanographer with the National Marine Fisheries Service, though they can reduce the growth of phytoplankton that form the base of the marine food web. "But when there are very high tides or storm surges, their effects can be amplified," he said.

If the rising waters coincide with other climatic events, such as rainstorms and high tides, the phenomenon could swallow beaches, chew away bluffs and coastlines, and submerge streets, homes and businesses. "This coming Kelvin wave is just the beginning," said Dr Jonathan Warrick, a research geologist at the US Geological Survey. "The thing to look out for is what will happen in January, February and March -- that's when we get the biggest storms, we get our largest waves and we have some very large tides." If these events align, their effects will compound, setting the stage for a tumultuous winter. Together, Warrick said, the systems will pack a far bigger punch. "When it comes to these storms and the tides," he said, "we really are kind of rolling the dice."

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