Friday, May 25 , 2018, 11:59 pm | Fair 62º

 
 
 
 

Ken Macdonald: The Big Blob in Our Pacific Backyard, and Its Local Impacts

It sounds like a creepy entity from a cheap horror film, but it is very real and it is in our oceanic backyard: A giant “blob” of warm water that appeared a year and a half ago.

The blob first showed up in satellite images in late 2013. By October 2014, it had splatted against the West Coast, and it split in two last month, with one blob off the Pacific Northwest coast and one offshore from Baja and Southern California, extending into the Santa Barbara Channel (see image below from Science, sciencemag.org).

The blob started out more than 1,000 miles across and 300 feet thick, and it contains water about 2 degrees to 8 degrees Fahrenheit warmer than usual. Why is this important?

The warm water is acting like a lid, suppressing upwelling. This means that nutrients normally re-circulated to the sea surface by upwelling are stranded down deep.​ As a result, the entire food chain, starting with plant plankton, suffers.

Populations of small schooling fish are low (especially California sardines). This is probably one reason why we are seeing a record die-off of sea lion pups in our waters (another reason is that the sea lion population has doubled since 1990, causing more competition for available food).

Other strange things are happening, too. Tropical species such as pygmy killer whales are showing up in Southern California waters. Large numbers of velella velella (related to jellyfish) are showing up in the channel.

Seabirds (such as the Cassin’s auklet) have been dying off. There is growing concern that the seasonal salmon run, which supports a multibillion-dollar industry, will be seriously affected because juvenile salmon headed into the Pacific may find very little to eat.

Why is this happening? A huge blob of warm water appears — is it global warming rearing its ugly head?

Climatologists are not unified in their opinion. About a third think it is probably related, a third say they don’t know and a third doubt that it’s related. (So if there is a conspiracy among climatologists to push a global-warming agenda, they aren’t hanging together very tight on this one!)

Macdonald graphic

At the same time that we are seeing unusually warm water on our side of the Pacific, it’s unusually cold on the Japan side. This pattern is typical of what is called the Pacific Decadal Oscillation, or PDO.

This phenomenon was first documented in the late 1990s, and its causes have remained a bit of a mystery. Like the El Niño/La Niña pattern, PDO can turn our West Coast upwelling off and on, but PDO’s effects are largely confined to the northern Pacific, and act over longer time scales (decades rather than years).

This particular incarnation of the PDO seems to be associated with a huge ridge of high atmospheric pressure parked along western North America. This high pressure ridge has suppressed winds that normally would trigger upwelling of cool, nutrient-rich waters. The ridge also has contributed to our drought by fending off rain storms.

To summarize: Instead of having normal winter rain; coastal upwelling of cold, nutrient-rich deep water; and cool coastal temperatures, we have had little rain and a huge warm water lid that shuts off upwelling and raises seasonal average coastal temperatures well above normal.

I have not been able to get an answer yet to any of my queries about why we are stuck with this ridge of high pressure, and whether the ridge causes, or is caused by, the PDO.

Because of the reduction of upwelling in the Santa Barbara Channel, I am concerned about the whales that visit our waters. Right now, gray whales and their calves are migrating from the warm lagoons of Baja up to the Gulf of Alaska and beyond. They don’t feed here, they’re just passing through. (It’s a good time to see them!)

But the humpback and the giant blue whales do come to our waters to feed in spring and summer; the big blues on krill, the humpbacks on schooling fish as well as krill. A few have already arrived, and I do hope that it is not slim pickings for them.

So, for many reasons, I hope the ridge and the blob move out soon!

F.Y.I.

Thank you to Rachel Haymon, a professor emerita in the UC Santa Barbara Department of Earth Science, for assistance on this article.

— Ken Macdonald is an oceanographer and professor emeritus in UC Santa Barbara’s Department of Earth Science. He has been affiliated with Woods Hole Oceanographic Institution and Scripps Institution of Oceanography, and has led deep-sea dives up to 15,000 feet in the submersible Alvin. He is a naturalist for Channel Islands National Park and the Channel Islands National Marine SanctuaryClick here to read previous columns. The opinions expressed are his own.

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