Between 2014 and 2015, a marine heatwave known as “The Blob” warmed an area of the Pacific Ocean larger than the United States and Mexico combined. The massive event fueled toxic algae blooms, collapsed fisheries, killed off millions of emaciated seabirds, sent dead fin whales (Balaenoptera physalus) and sea otters washing up on Alaska and British Columbia coasts, and dotted California shores with starving sea lions. Though best known as a marine heat wave, The Blob was also an extreme acidification event. Yet occurrences of these compound heat-acidity extreme events remain poorly understood. A new study, published in the journal AGU Advances in August, provides a detailed look at the frequency, intensity and duration of these compound events during the last four decades. The study reveals an understudied aspect of marine heat waves that could have implications for the developing 2026-2027 “super” El Niño, in which waters in the equatorial Pacific become unusually warm due to changing wind patterns. An underweight sea lion pup on a beach in February 2015. Image by NOAA Fisheries West Coast. Researchers from the Swiss Federal Institute of Technology (ETH Zurich) found compound heat-acidity events across the globe happen together “more frequently than would be expected by chance,” they wrote. Instead, the researchers attributed their occurrence to underlying ocean physics that allow marine heat waves to become unusually acidic in some regions. These events are mostly short-lived and small, with 67% of the 500 identified events lasting less than three months and extending to an…This article was originally published on Mongabay

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