Ocean temperatures as high as five degrees Fahrenheit above normal stretch from Alaska to Southern California. It’s second only to The Blob of 2014 and 2015, which caused cascading changes in the marine ecosystem. And already, the mass of warming water is hotter than in the early days of the last event. Current forecasts show it continuing for months.
Scientists fear it could be as hot and last as long as The Blob, which caused the largest harmful algal bloom ever recorded. The last event also dramatically reduced runs of endangered salmon and imperiled the animals that eat salmon, causing record numbers of whales forced to forage closer to shore to become entangled in crab traps and fishing lines.
The Blob also forced sea lion mothers on Southern California’s Channel to hunt farther from their young. Left alone, thousands of hungry cubs became stranded when they tried to follow their mothers.
“It’s on a trajectory to be as strong as the prior event,” Andrew Leising, a research scientist with National Oceanic and Atmospheric Administration who created a satellite tracking system to measure heatwaves in the Pacific Ocean, said in a statement. “Already, on its own, it is one of the most significant events that we’ve seen.”
Leising said he first noticed the new heatwave last fall, when he was still analyzing the effects of The Blob. The hot water dissipated last spring before re-emerging in June, Leising said over the phone.
The current heatwave is similar in size and surface water temperature increase. But there’s a major difference: hotter water is so far sticking to the surface and not extending as deep into the ocean as The Blob did. Leising said that means that even if the hot water soon comes all the way to shore, like The Blob did, the effects might not be the same.
“It’s really important to note – we really only have a sample of one,” Leising said. “We might have different impacts that we just can’t anticipate.”
Either way, it’s likely the heatwave has already harmed marine life off the West Coast. One indicator is a change in the habits of albacore tuna. They are swimming closer to shore, where they have been easier to catch, handing fishermen a record-setting season. And like The Blob, the current heatwave has probably reduced the food available to young salmon swimming out to sea.
“We know things are changing,” Chris Harvey, a research scientist at the Northwest Fisheries Science Center, said in an interview. “We just don’t know yet if this is going to have the very negative effects that The Blob did.”
NOAA teams are aggressively monitoring the situation. They are continuously collecting satellite imagery data showing ocean surface temperatures and collecting ocean samples, looking at water temperature and chemistry.
They’re also evaluating the nutritional value of plankton – the basis for all life in the ocean. Fattier plankton are associated with colder waters and are better for salmon and the small, schooling fish that feed so many other ocean creatures. Plankton lower in fat are linked to warmer, less productive water.
Over the winter, teams will monitor birth rates and survival of sea lion pups on San Miguel Island in California to get a sense of the conditions for marine mammals. And in the spring, teams will catch juvenile salmon to see if their abundance and growth rates have been affected.
Harvey said those will all be indicators of whether this is a severe event.
“It could be that this event turns out to be a short one if the wind picks up and is able to get rid of some of this heat,” Harvey said. “Then it could be that we dodged a bullet. But if it sticks around over the winter, then we’re going to be very concerned about it.”