The previous’s excessive ocean warmth waves are actually the brand new regular

Yesterday’s scorching ocean extremes are at the moment’s new regular. A brand new evaluation of floor ocean temperatures over the previous 150 years reveals that in 2019, 57 p.c of the ocean’s floor skilled temperatures not often seen a century in the past, researchers report February 1 in PLOS Local weather.

To supply context for the frequency and period of recent excessive warmth occasions, marine ecologists Kisei Tanaka, now on the Nationwide Oceanic and Atmospheric Administration in Honolulu, and Kyle Van Houtan, now on the Loggerhead Marinelife Heart in Juno Seashore, Fla., analyzed month-to-month sea-surface temperatures from 1870 by means of 2019, mapping the place and when excessive warmth occasions occurred decade to decade.

month-to-month extremes somewhat than annual averages revealed new benchmarks in how the ocean is altering. Increasingly patches of water hit excessive temperatures over time, the group discovered. Then, in 2014, all the ocean hit the “point of no return,” Van Houtan says. Starting that yr, no less than half of the ocean’s floor waters noticed temperatures hotter than probably the most excessive occasions from 1870 to 1919.

Marine warmth waves are outlined as no less than 5 days of unusually excessive temperatures for a patch of ocean. Warmth waves wreak havoc on ocean ecosystems, resulting in seabird hunger, coral bleaching, dying kelp forests, and migration of fish, whales and turtles seeking cooler waters (SN: 1/15/20; SN: 8/10/20).

In Could 2021, NOAA introduced that it was updating its “climate normals” — what the company makes use of to place day by day climate occasions in historic context — from the common 1981–2010 values to the upper 1991–2020 averages (SN: 5/26/21). 

This research emphasizes that ocean warmth extremes are additionally now the norm, Van Houtan says. “Much of the public discussion now on climate change is about future events, and whether or not they might happen,” he says. “Extreme heat became common in our ocean in 2014. It’s a documented historical fact, not a future possibility.”