From a small building at the end of the Ellen Browning Scripps Memorial Pier in La Jolla, aquarist Melissa Torres reels in a bucket with ocean surface water and looks at a digital thermometer — the same way researchers have taken daily measurements of ocean temperatures from the pier over the past 100 years.
On this recent Monday, the temperature is 18.95 degrees Celsius, or 66 degrees Fahrenheit.
“That’s warm,” said Torres. “Yesterday was 17.97 (degrees Celsius). But, yes, usually, we like to see around 16.”
Torres said the average ocean surface temperature off the La Jolla coast is about 61 degrees Fahrenheit. But for months, temperatures all along the West Coast have risen 3 to 4 degrees Fahrenheit above normal. They’ve also been warmer deep below the surface.
“By November, all of the stations (where measurements of ocean temperatures are taken) were showing record-high temperatures, and that wasn’t consistent every single day until January,” said Melissa Carter, a biological oceanographer managing Scripps Institution of Oceanography’s Shore Stations program. “In January and February, we started seeing these consistent, 90th percentile, 95th percentile, record breaking temperatures that were occurring along the coast.”
A marine heat wave is a period of unusually high ocean temperatures and they can have significant impacts on marine life as well as coastal communities and economies, according to the National Oceanic and Atmospheric Administration (NOAA).
Scientists say this heat wave is raising alarms because the coastal ocean has remained warm without an El Niño at the equator.
“Normally, we only get this kind of heat wave on the coast like this during an El Niño, but we're not currently in the El Niño,” said NOAA researcher Andrew Leising. “All the warming we're seeing now is left over from basically the marine heat wave that started last year.”
He said this monthslong ocean event rivals but has not reached the level of “the blob” from 2014 to 2016. That massive heat wave resulted in a record outbreak of toxic algae that shut down crab fisheries, changed salmon migration routes and led to starving sea lions and other animals, among other ecological impacts, according to NOAA.
Now, scientists are monitoring a separate heat wave that is forming hundreds of miles off the Pacific coast. That one is part of a pattern observed over the last decade.
“Every year we seem to be getting these heat waves that start way offshore about this time of year, get bigger and get to the coast and impact us, typically get us in the late summer and fall,” said Leising. “That does seem to be something that is kind of the new normal ever since the blob.”
He’s monitoring whether the two marine heat waves will merge in the late summer or fall.
“The question will be, (if) we're going to roll right into an El Niño on top of that, which will keep the water warm in the coastal region again,” said Leising. “If that happens by next year this time, we'll probably see a lot more impacts, because at that point, the animals, especially in California, will have been exposed to this heat for not just a month or two, but almost a whole year.”
Already, the current marine heat wave has led to some noticeable wildlife impacts.
“We have been seeing an increase in the number of seabirds coming into rehabilitation facilities and washing up dead on the beaches across southern and central California for a few months now,” Tammy Russell, a marine seabird expert at Scripps, said in a statement. “Most of the birds are emaciated and have tested negative for HPAI (avian flu); therefore, we have concluded that the primary cause of this mortality event is due to starvation.”
If the ocean is warmer than normal, it can impact the food web in multiple ways, she added.
“Fish and other organisms that require cooler waters to survive can move to cooler locations (north or deeper), resulting in lower food availability in warmer regions,” said Russell. “Additionally, warmer conditions can stratify the water column, reducing the nutrient supply that reaches the surface waters and have cascading impacts on the entire food web.”
NOAA’s El Niño forecast, published this week, shows a 61% chance the weather system will form by July and persist through the end of the year. The Pacific climate pattern brings warmer sea surface temperatures, increased humidity, and a higher likelihood of a wet winter.
