Storm waves eroded the dunes from beneath homes in Pajaro Dunes, Calif., on Monterey Bay, during the powerful 1982–83 El Niño. Credit: Gary Griggs

California's coastal bluffs and beaches look rugged, but they can be surprisingly fragile in the face of a powerful El Niño.

The state saw that in 1982–83, when storms amid one of the most destructive El Niño winters in California history battered the coastline with powerful waves and torrential rain, leaving hundreds of millions of dollars in damage in its wake. The storms coincided with elevated sea levels, high astronomical tides and very large waves delivered by repeated storms.

Extreme waves that winter destroyed one-third of the Santa Monica Pier and tore off large sections of the Huntington Beach Pier and the Paradise Cove Pier, while also damaging the Seal Beach, San Clemente and Malibu piers.…