A giant warm-water mass—similar to 'the blob'—could wreak havoc on West Coast marine life

"Sea surface temperature anomaly maps show temperatures above normal in orange and red," NOAA reports. "Sea surface temperature anomaly maps show temperatures above normal in orange and red," NOAA reports. Photo: NOAA Photo: NOAA Image 1 of / 4 Caption Close A giant warm-water mass—similar to 'the blob'—could wreak havoc on West Coast marine life 1 / 4 Back to Gallery

You might remember the blob.

Not the 1958 sci-fi movie, but the giant mass of warm water that formed in the Pacific Ocean in 2013 and continued to spread until 2015. It wreaked havoc on the West Coast marine ecosystem and dampened salmon runs.

Scientists with the National Oceanic and Atmospheric Administration have identified another expanse of warm water and say this marine heatwave could rival the blob. The impact on sea life could be devastating.

Ocean surface temperature maps show the warm mass stretching from Alaska to California. It currently "ranks as the second-largest marine heatwave in terms of area in the northern Pacific Ocean in the last 40 years, after 'the Blob,'" according to NOAA.

"It's on a trajectory to be as strong as the prior event," Andrew Leising, a research scientist at NOAA Fisheries' Southwest Fisheries Science Center in La Jolla, Calif., said in a statement. "Already, on its own, it is one of the most significant events that we've seen."

The warm water mass is miles offshore and formed in only a matter of months as a ridge of high-pressure over the Pacific Ocean lessened the winds that mix up ocean waters and cool the surface. In fall, the ocean sea breeze usually weakens on the West Coast, and this may allow the blob to approach shore, or it could dissipate.

"It looks bad, but it could also go away pretty quickly if the unusually persistent weather patterns that caused it change," said Nate Mantua, a research scientist at the Southwest Fisheries Science Center.

At its height, "the blob" pushed ocean temperatures 7 degrees above average. The impacts included an algal bloom that shut down crabbing and clamming, the stranding of thousands of California sea lions on beaches and reduction in food sources for salmon.

"We learned with 'the Blob' and similar events worldwide that what used to be unexpected is becoming more common," said Cisco Werner, NOAA fisheries director of scientific programs and chief science advisor. "We will continue to inform the public about how the heatwave is evolving, and what we might anticipate based on experience."

Amy Graff is a digital editor for SFGATE. Send her story tips and photos at agraff@sfgate.com.