Environment & Energy

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Another piece of the puzzle is the planet’s diminishing reflectivity, according to Brian McNoldy, an atmospheric scientist at the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science. The ocean’s dark surface helps it absorb heat, whereas white clouds and aerosol particles in the atmosphere help bounce the sun’s radiation back into space. In 2020, the International Maritime Organization adopted a new rule to cut back on sulfur pollution from shipping fuel, but because the aerosol particles in emissions acted as a seed for clouds, the regulation had the unintended effect of dimming the marine layer of clouds that blanket the ocean.

“So you get rid of a lot of those, and now more of the sun’s energy can be absorbed in the ocean instead of reflecting off clouds,” McNoldy said. According to Merchant, efforts to curb air pollution from factories in countries like China also had the side effect of cutting back reflective aerosols.

The excess ocean warmth has had wide-ranging consequences. In April 2024, as the oceans started simmering, 77 percent of the world’s coral reefs became imperiled in the most extensive bleaching event on record, threatening the livelihoods of a billion people and a quarter of marine life. Changing ocean temperatures also shift weather patterns, potentially intensifying droughts, downpours, and storms alike.

“Hurricanes love warmer water. So all other things be equal, a warmer ocean can produce stronger hurricanes with maybe more frequent instances of rapid intensification,” McNoldy said. Last September, Hurricane Helene slammed into Florida’s Gulf Coast after surging from a Category 1 to a Category 4 storm in a single day.

“The oceans really set the pace for global warming for the Earth as a whole,” Merchant said. The knock-on effects — like wildfires, drought, and floods — will continue to escalate, too. “That really needs to be understood, but it also needs to filter through to governments that changes might be coming down the line faster than they’re currently assuming.”

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https://grist.org/oceans/why-earth-oceans-record-hot-streak/