Kelvin wave doubles coastal flood risk

A strong Pacific Kelvin wave can temporarily add on the order of a foot to local sea levels, meaning it can double short‑term flood exposure in regions that have already seen 8–12 inches of century‑scale rise. When such subsurface swell events align with high tides, atmospheric storms, or seasonal surf, their compound effect can produce weeks of elevated shoreline inundation and accelerated bluff/shoreline erosion. — The idea reframes sea‑level rise from a slow, monotonic threat into a hazard with episodic, predictable compounding events that demand different emergency planning, permitting, and insurance responses.