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A first as the world warms: New forecasts could help predict marine heat waves

Multiple marine heat waves have occurred since 2014 along the Washington coast
This submitted photo shows Paul Cottrell, wearing the red jacket, helping to disentangle a humpback whale.

Marine heat waves have caused major ecological disruptions along the Pacific coast in recent years, but scientists have developed a global forecasting system to help fisheries and coastal communities anticipate and prepare for these extreme weather events.

The scientific journal Nature on Wednesday published the forecasting system that provides projections on marine heat waves around the world up to a year in advance.

Researchers said the new forecasts could provide vital information as climate change causes marine heat waves to become increasingly frequent and intense.

“These marine heat waves are the expression of when natural variability meets up with anthropogenic climate change and results in these episodic but extreme events,” said Elliott Hazen, a co-author of the report and research ecologist at the National Oceanic and Atmospheric Administration Southwest Fisheries Science Center in Monterey, California. “With marine heat waves come both new opportunity and new risk.”

Most recently, a heat wave that began to accumulate in 2013 along the West Coast — more commonly known as “the blob” — disrupted fish stocks, triggered damaging algal blooms and threw the ocean’s ecological balance off-kilter. The blob peaked in 2014 and fizzled in 2016, but research from earlier this year indicated the impacts persisted long after ocean temperatures returned to normal.

The blob fueled a massive increase in the population density of California market squid along the Oregon and Washington coasts, according to a report published in January by the American Fisheries Society.

“Hopefully this is something that can help mitigate those potential negative impacts in the future, or even help with seizing opportunities that might arise due to marine heat waves,” said Michael Jacox, lead author and NOAA research scientist at the Southwest Fisheries Science Center and the Physical Sciences Laboratory in Boulder, Colorado.

Jacox said the northeast Pacific is already showing signs of a marine heat wave but not very close to shore.

“Which would be good news certainly if that plays out,” he said.

In California’s coastal waters, the 2013 heat wave forced humpback whales to hunt closer to shore where warmer temperatures caused a bloom of toxic algae that led to delays for Dungeness crab fisheries. As a result, fisheries saw an abrupt increase in the number of whales tangled in ropes attached to those crab traps.

The new forecasts could help prevent situations like that, Hazen said. “There really hasn’t been any operational marine heat wave forecasts in place,” he said. “So this really is a first.”

Around the world, unexpected spikes in ocean temperatures have caused huge losses in fish, shellfish and coral.

Marine heat waves are a contemporary phenomenon about which scientific knowledge is limited. The relationship between warming ocean temperatures and unpredictable marine heat waves, as well as their impact on land temperatures, remains to be fully understood, according to Nick Bond, the Washington state climatologist at UW.

“As the oceans continue to warm, these sorts of heat waves are going to be coming along that much more, and they’ll probably be that much more severe,” he said.

Following the blob, NOAA developed the Marine Heatwave Tracker, which monitors northern Pacific coastal waters for evidence of an ongoing heat wave.

The forecasts published Wednesday, however, can be used to predict where a marine heat wave is likely to develop — and for how long — up to a year in advance.

Due to greater atmospheric and oceanic fluctuations, the forecasts cannot be used as effectively on the East Coast or in the Mediterranean Sea. Predictions are most accurate, researchers said, during El Nino.

The El Niño Southern Oscillation is a two- to seven-year cycle during which ocean temperatures in the eastern Pacific undergo a warming and cooling cycle. Each cycle has a large impact on currents, fisheries and the weather.

While past methods of predicting heat waves could provide an understanding of ongoing weather events, or long-term changes in oceans and marine ecosystems, Jacox said the new forecasts could fill that gap.

The forecasts, he said, are “one piece of the puzzle.”

Multiple marine heat waves have occurred since 2014 along the Washington coast. In most cases, pools of water near the center of the blob can become warmer by up to 5 degrees Fahrenheit, and by 1 to 2 degrees at the edges.

A 2016 study found that marine heat waves have increased in frequency since the 1970s.

The ocean captures about a third of the planet’s excess carbon and more than 90% of its excess heat.

“When you think about the whole climate system,” Bond said. “It behooves us, obviously, to keep track of the oceans.”

—Nicholas Turner, The Seattle Times

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