On a quiet Monday afternoon in Santa Cruz, families lounged on the beach as a few swimmers played in the waves and a lone fisherman cast his line in the water from the cliffs off in the distance.
It was, by all accounts, a beautiful day. But just a few miles away at the Santa Cruz NOAA research campus, scientists see those perfect conditions as a quiet omen of what's brewing just over the horizon.
"We're talking about a huge area of much warmer-than-normal surface temperatures over the northeast Pacific Ocean," said NOAA research scientist Nate Mantua.
Mantua is NOAA's resident expert on what have come to be known as "blob events" — marine heat waves like the one discovered in late 2013, in nearly the same spot as the current warm spot. That event, now immortalized in Wikipedia as "The Blob (Pacific Ocean)" persisted, on and off, for most of three years.
"We all know about heat waves on land," Mantua said. "We live through them. Sometimes they last for a couple of days."
A marine heat wave is a similar phenomenon: a pocket of warm air that simply stops moving due to a lack of wind, and heats everything below it until atmospheric conditions start moving it along again. But in the middle of the Pacific Ocean, these events can last for weeks, months or even years — and the last one had dramatic effects on the ocean's fragile ecosystem.
"For California sea lions, lots of pups were starving and abandoned by their moms," Mantua said. "And a spike in whale entanglements in fishing gear, especially Dungeness crab fishing gear."
The death and suffering among marine mammals along the coast, Mantua said, was the result of a long chain reaction that started about a thousand miles off the California coast, just north of Hawaii. A patch of water about three times the size of Alaska, and 150 feet deep, was found to have water temperatures as much as 7 degrees Fahrenheit warmer than the average.
Historically, Mantua said, the slow progression of climate change has accounted for about a 1.5-degree increase in average ocean temperatures over the past century — so a 7-degree increase is more than enough to cause havoc. It starts with a change in currents deep below the surface that prevents nutrients on the ocean floor from rising into shallower water. That causes plankton to die off, and sends the fish that eat the plankton searching for food in chillier water near the shore.
For humans, that has an upside: great sport fishing for warmer-water fish like albacore tuna that would normally be too far away to catch. But for mammals that live in the ocean, it means competition: sea lions, whales and shore birds all crammed into a tiny sliver of cool water near the coast, all looking for fish.
With this new warm blob, Mantua says some of the same problems are already starting to appear. Though there's no reliable way to predict how long the warm patch will stick around, he said, the impact on marine life and fisheries could be significant if it doesn't dissipate soon.
"The whales (during the last blob event) were feeding much more in-shore than they typically were found, especially humpback whales targeting anchovies, and we're looking at a similar situation now where there's a lot of anchovies along California's central coast," he said. "So if the whales stay in these shallow waters on the (continental) shelf, that can put them much more in conflict with fishing gear."
The Dungeness crab fishery experienced other problems during the 2014-2016 event, including a drastically shortened season due to a toxic algae bloom. The algae produced an acid that didn't harm the crabs, but was poisonous to anyone who ate them. Scientists believe the over-abundance of toxic algae during those years was a result of the unusually warm water.
Though meteorologists are just beginning to get a handle on what causes "blob events" — and why they're so stubborn — Mantua says there does seem to be a correlation with warming in other parts of the world.
"It may be related to conditions in the tropics, or at high latitude, where the Arctic is especially warm again this summer and sea ice is very scarce," he said. "So we've got big changes going on around the whole planet that can influence the weather of the North Pacific."
The ocean, he said, has taken the brunt of the impact from human-caused climate change — and occasionally shows it with prolonged weather events like El Niño that begin over water, but can have disruptive effects over land.
"The oceans are a huge reservoir for thermal energy, so as they warm up, they're holding onto a lot of that heat," he said. "(When) they give some of that back to the atmosphere … it disrupts weather patterns, and we can feel that — whether it's with big flood events, or droughts, or heat waves. So it's a critical part of the climate system — and it's changing."