Conservation news

‘The Blob’ is back: Pacific heat wave already second-largest in recent history

  • The original Blob was a vast expanse of unusually warm water in the northeast Pacific that persisted from 2014 to mid-2016. (The unusual moniker came about because the marine heatwave appeared as a giant red blob on ocean surface temperature maps.) It eventually stretched all the way from the Gulf of Alaska to the California coast and had a number of adverse effects, contributing to a global coral bleaching event and impacting coastal salmon fisheries.
  • The new Blob resembles the first in extent and location, according to the US National Oceanic and Atmospheric Administration (NOAA), which reported on September 5 that the current marine heat wave in the northern Pacific is already the second-largest recorded in the past 40 years, behind only the 2014-2016 Blob.
  • Sea surface temperatures in the northeast Pacific have been more than 3 degrees Celsius above average during the current heat wave. In the 2014-2016 Blob, water temperatures reached up to 5.5 degrees Celsius above average in some places.

“The Blob” is back in the Pacific Ocean.

The original Blob was a vast expanse of unusually warm water in the northeast Pacific that persisted from 2014 to mid-2016. (The unusual moniker came about because the marine heatwave appeared as a giant red blob on ocean surface temperature maps.) It eventually stretched all the way from the Gulf of Alaska to the coast of Mexico and had a number of adverse effects, contributing to a global coral bleaching event and impacting coastal salmon fisheries.

The new Blob resembles the first in extent and location, according to the US National Oceanic and Atmospheric Administration (NOAA), which reported on September 5 that the current marine heat wave in the northern Pacific is already the second-largest recorded in the past 40 years, behind only the 2014-2016 Blob.

Like its predecessor, the new Blob might already be contributing to coral bleaching, which occurs when coral polyps expel algae that live inside their tissues in response to stressors like warmer water temperatures. “Ocean temperatures are extremely warm right now across the main Hawaiian Islands,” NOAA scientist Jamison Gove said in a statement. “They’re up to 3.5°F warmer than what we typically experience this time of year. If the ocean continues to warm even further as predicted, we are likely to witness a repeat of unprecedented bleaching events in 2014 and 2015.”

The current northeast Pacific heatwave is “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, California, said in a statement. “Already, on its own, it is one of the most significant events that we’ve seen.”

There are believed to be a number of causes for the warmer ocean waters, from natural variability and weather patterns to the ongoing impacts of global climate change.

Sea surface temperature anomaly maps show temperatures above normal in orange and red. Credit: NOAA.

Leising developed a tool called the California Current Marine Heatwave Tracker that uses satellite data to track marine heat waves in the Pacific Ocean. According to the California Current website, “This new marine heatwave is currently referred to as the Northeast Pacific Marine Heatwave of 2019, or NEP19. Like the blob, NEP19 emerged over the past few months as a ridge of high pressure dampened the winds that otherwise mix and cool the ocean’s surface.”

Sea surface temperatures in the northeast Pacific have been more than 3 degrees Celsius above average during the current heat wave. In the 2014-2016 Blob, water temperatures reached up to 5.5 degrees Celsius above average in some places.

Leising told the Washington Post that the warm waters haven’t yet reached too deep into the Pacific, only about 65 feet at most, which is relatively shallow compared to the nearly 400-foot-depths reached by some parts of the 2014-2016 Blob. Because it is primarily only affecting the upper layers of the ocean, it’s possible that the current heatwave could dissipate before it has time to make a lasting impact on the marine ecosystem.

According to NOAA, however, biologists say that NEP19 is large enough that it probably already has impacted the marine ecosystem: “For example, warmer conditions during ‘the Blob’ left lesser-quality food available to young salmon entering the ocean. It also shifted predator distributions in ways that contributed to low returns of salmon.” Other impacts of the 2014-2016 Blob included an algal bloom on the US West Coast that shut down crabbing and clamming for several months, thousands of sea lion strandings on beaches, and multiple fisheries disasters being declared.

So far, upwelling of colder water along the west coast of the US has mostly kept the expanse of warmer Pacific waters out to sea, though NOAA reports that “it appears to have come ashore in Washington and could do so in other areas as upwelling wanes in the fall.” But if current atmospheric conditions continue into the fall and the new Blob moves into nearshore coastal waters, it could impact coastal ecosystems.

“We learned with ‘the Blob’ and similar events worldwide that what used to be unexpected is becoming more common,” Cisco Werner, NOAA Fisheries Director of Scientific Programs and Chief Science Advisor, said in a statement. “We will continue to inform the public about how the heatwave is evolving, and what we might anticipate based on experience.”

This story is part of Covering Climate Now, a global collaboration of more than 300 outlets worldwide to strengthen coverage of the climate story.

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