The ocean at Scripps Pier
The ocean temperature at Scripps Pier on Thursday was the highest ever recorded on Sept. 5. Courtesy of Scripps Institution of Oceanography

A giant mass of warm Pacific Ocean water similar to one that disrupted the West Coast marine ecosystem in 2014 has emerged this summer, according to NOAA scientists in La Jolla.

The NOAA Fisheries’ Southwest Fisheries Science Center reported Thursday the warm expanse building off the West Coast stretches from Alaska south to California. It ranks as the second largest marine heatwave in terms of area in 40 years.

“It’s on a trajectory to be as strong as the prior event,” said Andrew Leising, a research scientist at the center, in an official post on the NOAA website. “Already, on its own, it is one of the most significant events that we’ve seen.”

The 2014 event, nicknamed “the blob,” caused the largest harmful algae bloom recorded on the West Coast, shutting down crabbing and clamming for months and leaving thousands of young California sea lions stranded on beaches.

Charts compare Pacific Oceans warming in 2014 and 2019
Pacific Ocean warming in 2014 and 2019 compared. Courtesy NOAA

The warmest areas of this year’s blob are 5 degrees above normal.

Leising said cold water welling up from ocean depths along the coast has so far held the warm expanse offshore. However, the upwelling, driven by coastal winds, usually wanes in the fall.

The heatwave could then move onshore and affect coastal temperatures, he said, adding that this already appears to have happened along the coast of Washington.

Also on Thursday, the Scripps Institution of Oceanography recorded the highest water temperature ever measured at Scripps Pier on Sept. 5 — 78.3 degrees.

Chris Jennewein is founder and senior editor of Times of San Diego.