What a persistent ocean heatwave means for sea life and a possible El Niño year

California has had a spate of abnormally large marine heatwaves in the past 12 years. Typically, they’ve started far offshore in the spring, reached our coast by the fall, then receded by late winter, according to the National Oceanic and Atmospheric Association, or NOAA.

But the current heatwave has stuck around pretty much all year — since last May, particularly off the Central and Southern California coastline.

“The only time you ever see that would be during an El Niño, but we're not in El Niño yet,” said Andrew Leising,  an oceanographer with NOAA’s Southwest Fisheries Science Center.

El Niño is likely to hit our region in the coming months, though it remains to be seen how strong it could be. El Niño is a natural global climate pattern that occurs every three to seven years, when trade winds — the prevailing east-to-west winds that circle the Earth near the equator — weaken, and waters in the eastern and central equatorial Pacific warm up.

The key point, said Leising, is that El Niño isn’t here yet. So why is the ocean so warm?

'A new normal' 

It’s likely a sign of how human-caused climate change — driven by the pollution we’ve pumped into our atmosphere — is making natural cycles more extreme, experts say.

"Approximately 30% to 45% of the affected ocean area is experiencing conditions that are at least six times more likely due to human-caused warming," according to Climate Central.

A NOAA expert said the evidence of climate change's effects on ocean temperatures has been growing since 2014.

“ How much that is, whether there's feedback with the atmosphere, that's what's really difficult to quantify just because it's never one thing acting on its own," said Elliott Hazen, an NOAA ecologist.

The latest conditions of the ongoing marine heatwave off our coast.

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Courtesy NOAA

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Leising called the regularity of these marine heatwaves “a new normal.”

“It's very possible that the long-term change in the atmosphere is what's flipped the switch between fewer and now more heatwaves,” he said.

2014 was a major turning point. That’s when a massive marine heatwave dubbed “The Blob” started, persisting until mid-2016. It caused harmful algae blooms and mass dieoffs of marine life. It also coincided with El Niño.

So far this marine heatwave’s effects aren’t as widespread as The Blob’s. But the current pattern is echoing what led to that devastating event.

An uptick in dead and emaciated seabirds along our coast is one possible sign. Scientists are increasingly pointing to the deaths as related to the heatwave. Why? As birds’ typical food sources move into deeper, cooler waters where birds can’t reach, the birds starve.

The forecast

The warm waters are unlikely to let up anytime soon with El Niño on the horizon.

For us on land in Southern California, that could mean less June gloom, a hotter, humid summer and a dangerously wet winter.

For animals underwater, such as stingrays and juvenile white sharks, those warmer temperatures can be something of a boon — experts are predicting more stingray stings and shark sightings this summer at our local beaches.

A round stingray, the most common type of stingray living along our shore and the most likely to sting you.

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Courtesy CSULB Shark Lab

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But for other creatures, such as nesting birds or sea lions, as well as kelp forests that support that life, such heating can be devastating. Just like humans, living in high temperatures for a prolonged period can be deadly for marine plants and animals.

“We might just roll from one thing into the next, and that's really where some of the biggest impacts lie, is that cumulative stress on the animals,” Leising said.

Warmer waters also mean less upwelling — when deep, cold ocean water rises to the surface.

That means “less nutrients, and just less total productivity,” Leising said. “So there's just not as much stuff at the bottom of the food web to feed everything else.”

There’s still a lot unknown about these escalating marine heatwaves, but cuts to NOAA under the Trump administration could jeopardize ongoing research.

“That kind of work is critical to understand how to respond,” Hazen said, “because the longer we take to respond, the more species end up dying, and the more economic consequences too.”