During the El Niño of 1983, Californians counted their blessings. The warm Pacific waters sloshing eastward certainly brought heavy spring rains and record snow. But the state largely escaped the flood risks being frantically managed farther east. That spring, engineers famously resorted to plywood to add just a few more inches to the 710-foot-high Glen Canyon Dam as they struggled to prevent the second-largest reservoir in the United States from being overtopped by El Niño-swollen waters. Back in California, a top flood official noted that it was “luck,” not preparation, that spared the state a similar fate. El Niño, a climate pattern driven by shifts in winds and currents in the tropical Pacific Ocean, is the stuff of nightmares the world over: Widespread crop failures, famine, disease, floods, extreme heat, droughts, wildfires and even violent conflict have all been linked to the recurring climate anomaly. 

Written by Justin S. Mankin a geography professor at Dartmouth College, and Christopher W. Callahan a doctoral candidate in geography at Dartmouth