Over the past several months, an intense marine heat wave has developed in the Pacific from Washington to Baja Mexico, with a particularly extreme hot spot between the Bay Area and San Diego. Ocean temperatures have spiked to as much as 7 degrees hotter than average, with many places breaking records for this time of year.The heatwave off the California coast is already causing starving birds to wash ashore and could increase the risk of thunderstorms and dry lightning that could worsen the wildfire season, scientists say.Researchers at the Scripps Institution of Oceanography at UC San Diego have recorded 38 days since Jan. 1 when the surface temperature off their La Jolla pier in San Diego broke records going as far back as 1916. On March 20, the ocean there reached 71 degrees, the hottest ever recorded in March and a level normally seen in August.“It’s extreme,” said Melissa Carter, a Scripps oceanographer. “We have had heat waves in the past. But this is a record event for the duration and the intensity.”Farther north, ocean temperatures also have broken records on 31 days this year off Newport Beach; 38 off Santa Barbara; 22 at Pacific Grove near Monterey; 9 days at the Farallon Islands off San Francisco; and 14 at Trinidad in Humboldt County.Scientists say the heat wave, which appears to be related to changes in wind patterns that limit the extent cold water in the deeper depths can move to the surface, and the intense high-pressure system that caused record hot, dry temperatures over the land in March, could bring hotter, more humid temperatures to California this summer. A similar marine heat wave, which became known as “The Blob,” affected California ocean temperatures in 2014 and 2015. During that event, normally chilly waters were balmy for beachgoers, swimmers and surfers. There were fewer foggy days at the beach. Humpback whales began feeding much closer to the coast, affording people amazing views of the animals — but also putting the whales in greater danger of collisions with ships and entanglement with fishing gear.
Huge blooms of algae emerged, shutting down crab and clam fishing for months. Salmon runs crashed. Ocean species normally seen in tropical waters began showing up much farther north along California, Oregon and Washington.
Closer to the shore, however, seabirds and young sea lions, who couldn’t get enough to eat because of changes in local fish patterns, began washing up by the thousands, malnourished and dead, along beaches. Wildlife rescue centers were overwhelmed.
“Sea lion pups were just starving,” said Dr. Cara Field, staff veterinarian at the Marine Mammal Center in Sausalito, which treated 1,800 distressed seals and sea lions in 2015, triple the normal number. “At 6 months of age, they were at their birth weight. They were completely emaciated. Many of them were dying despite our best efforts. It was very difficult to keep up with.”
The Blob also did significant damage to California’s kelp forests. And although the sea lions and other species have since recovered, kelp forests in many places, including off the Sonoma and Mendocino coasts, are still struggling.
“We’re concerned that it could happen again,” said Anita Giraldo Ospina, a marine scientist with the Monterey Bay Aquarium. “Many of our kelp forests have not recovered.”
The 2014-15 marine heat wave also worsened California’s severe drought, which stretched from 2012 to 2016.
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