At a pier in San Diego, researchers on Wednesday recorded the warmest sea surface temperature since record-keeping began there in 1916.
Every day, researchers from the Scripps Institution of Oceanography at the University of California San Diego collect data — by hand — from the Ellen Browning Scripps Memorial Pier.
Wednesday's 78.6 degrees Fahrenheit at the pier surpassed a previous record of 78.4 degrees in 1931, researchers said in a statement on Thursday.
"It really is weird," Clarissa Anderson, a Scripps research scientist, told NPR. "We have different records going back decades and while [our ocean water] temperature is tightly connected with the equator, we're now seeing [temperatures] stabilize at the equator while temperatures in southern California keep going up."
Anderson said that it's not clear why southern California's ocean temperature patterns appear to be diverging from the equator's.
The water that laps against southern California has experienced "anomalously warm" temperatures, and it's consistent with high temperatures on land, the researchers said.
Temperatures rose in 2014 during "the blob," a marine heat wave that started in the northern Pacific and spread along the coast, changing marine life and causing a massive bloom of toxic algae. "The temperatures we recorded ever since then were on a reset. They were at a higher level and never came back down," said Anderson.
In 2015, a strong El Niño took its toll on California. And in that part of the Pacific, water temperatures, which Anderson said often return to historic averages after the climate phenomenon, never decreased.
That is causing eyebrows to raise in the region. "Like other climate change trends, background warming enhances the probability and magnitude of extreme events," Scripps oceanographer Reinhard Flick said in the statement.
Warmer waters could lead to another sprawling bloom of toxic algae, which harmed sea lions and other marine life, as well as caused fisheries to close. It could also bring stingrays to shore and lead to more jelly fish in the ocean, altering the food web for marine life.
Rising ocean temperatures are not just a problem for the West coast. The last three decades have seen consistently higher sea surface temperatures than at any other time since 1880, when reliable observations started, the Environmental Protection Agency said.
On land, last year was the warmest non-El Niño year ever recorded, according to NOAA, as NPR's Laurel Wamsley reported.
"This is how global warming will play out," the researchers said. Heat records will become "easier to break" and people will see the mounting effects of climate change.
"If you put everything together — wildfire explosions on the West coast and the increases in air temperatures, combined with rising seawater temperature — it's telling us a story," said Anderson. "We need to respond to that story."