El Niño could bring the highest sea levels ever recorded along the Southern California coast, according to a climate scientist at UC San Diego’s Scripps Institution of Oceanography. Mark Merrifield, director of the Center for Climate Change Impacts and Adaptation, says satellite data from NASA shows sea levels in the eastern Pacific are already more than half a foot above the reference level. Warmer ocean water causes sea levels to rise because water expands as temperatures increase. Scientists also say historical data shows El Niño events can produce extremely powerful waves, raising concerns about coastal flooding and widespread damage. Forecasters are increasingly warning that this year’s El Niño could become a historically strong event, potentially bringing a combination of elevated sea levels, dangerous surf, heavy rainfall, and additional heatwaves.