The ‘blob’ is back — except this time it stretches across the entire North Pacific

By Andrew Freedman, CNN

(CNN) — A record-breaking and astonishingly expansive marine heat wave is underway in the Pacific Ocean, stretching about 5,000 miles from the water around Japan to the West Coast of the United States. The abnormally warm “blob” of ocean water, which is getting a significant boost from human-caused global warming, is affecting the weather on land and could have ripple effects on marine life.

The hot ocean waters around Japan contributed to that country’s hottest summer on record, which featured its all-time national maximum temperature record, set on August 5, at 107.2 degrees Fahrenheit.

On the other side of the Pacific, the ocean heat is also yielding higher humidity in northern California at the start of meteorological fall, and if it persists, could enhance rain and mountain snowfall from wintertime atmospheric rivers.

The sea surface temperature difference from average across the entire North Pacific smashed an all-time record for the month of August, with reliable data stretching back to the late 19th century.

What worries scientists is the repetitive nature of these events. As climate change causes more heat to be stored in the oceans, ocean temperatures are reaching new heights that could lead to more significant impacts from these heat waves like this.

The North Pacific warmed at the fastest rate of any ocean basin on Earth during the past decade, according to Michael McPhaden, a senior scientist at the National Oceanic and Atmospheric Administration.

And the entire North Pacific Ocean Basin is involved in the current marine heat wave, standing out starkly on weather maps. This event is unique for its intensity and extraordinary geographic reach, and for its potential to eventually alter large-scale weather patterns if it continues.

If the broad ocean basin-wide heat wave persists, it could influence the wintertime storm track associated with the jet stream, said Daniel Swain, a climate scientist at the University of California, Los Angeles.

In parts of the North Pacific, from the Gulf of Alaska south to the coast of California, this heat wave is known as a “blob” of unusually hot water. It is part of a pattern of marine heat waves in this area following a severe heating event in 2013 that lasted until 2016. That heat wave remains the most severe on record.

The moniker refers to how the area of warm water looks on maps showing how different sea surface temperatures are from average. This year it may be something of a misnomer, since the marine heat wave is so huge that it spans the Pacific. It also originated in the Western Pacific and gradually extended eastward.

Past Northeast Pacific Ocean blobs led to a historic die-off of seabirds in coastal Alaska, and affected fish species along with sea lions and other creatures that call this region home.

The seabirds, known as common murres, still have not recovered from that marine heat wave, and impacts from the ongoing event have been observed on other species, according to Heather Renner, supervisory wildlife biologist at the Alaska Maritime National Wildlife Refuge.

“There have been multiple die-offs of marine mammals, seabirds and forage fish in Alaskan waters this summer; we have definitely had an uptick in calls from the public about sick and dead birds,” she said in an email. “These have all been much smaller than what was seen in 2015-2016 but have affected a wide variety of species.”

Renner says longer-lasting strong blob events tend to have greater effects on wildlife, and the ongoing one has not been present nearly as long as some past occurrences.

The current event ranks as the fourth-largest Northeast Pacific blob yet observed, according to data from NOAA oceanographer Andrew Leising.

The 2013 to 2016 event featured warm waters that extended deep into the upper layers of the ocean, which allowed it to persist through the stormy winter months. This one, however, is more likely to prove fleeting in the northeastern Pacific since it is more surface-based, according to Art Miller, an oceanographer at the Scripps Institution of Oceanography.

Once strong winds from late fall and early winter storms track across the region, they will likely be able to stir up cooler water from below the ocean surface, putting an end to this particular blob, Miller said.

“Since this is a summer anomaly, it is very likely confined to a very thin mixed layer depth,” Miller said. “So once the atmospheric conditions change, it should fade quickly into the ocean via vertical mixing and through losing heat to the atmosphere.”

The cause of the ongoing marine heat wave — both the blob in the northeast Pacific and the more enduring anomalies stretching westward to Japan — are the result of “persistent anomalous wind conditions” associated with stagnant high-and low-pressure areas, Miller said. These can influence how much cooler ocean waters rise from deeper depths, a process called upwelling.

This year, winds have been weaker than normal across the basin or blown in directions that discourage upwelling. When upwelling is curtailed by winds or other factors, surface water temperatures can soar. In recent years, this has become more common in this region during the spring and summer months, usually ending in the fall.

“There is concern that because these anomalies are happening with similar (but not exactly the same) structures that the persistent atmospheric pressure patterns might be part of an adjustment of the Pacific Ocean climate state to global warming conditions driven by greenhouse gases from fossil fuel burning,” Scripps’ Miller said in an email.

Multiple studies have been published that attribute an increase in marine heat waves and accelerated warming in the North Pacific Ocean to global warming pollution from burning fossil fuels. “The fingerprint of climate change is clearly evident in what is transpiring now in the North Pacific,” McPhaden said.

“The North Pacific has a fever, but the story doesn’t end there,” he said. “The downstream effects of these marine heatwaves is likely to be significant in terms of how they impact marine organisms, ecosystem structure, fisheries and the weather in the Pacific Northwest. Stay tuned.”

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