Oceans also in hot water

RESCUED A fur seal from Guadalupe is sheltered at a rescue facility in California, along with sea lions, because the temperatures in the Pacific remain high. -AP

WASHINGTON – Even the oceans break temperature records in this summer of heat waves.

Off the coast of San Diego, scientists recorded the highest seawater temperatures earlier this month since daily measurements began in 1916. [19659003] "Just as we have heat waves on land, we also have heat waves in the ocean," Art Miller said. from the Scripps Institution of Oceanography.

Between 1982 and 2016, the number of "marine heat waves" tripled roughly, and likely to become more common and intense as the planet warms up, a study released on Wednesday found.

Prolonged periods of extreme heat in the oceans can damage kelp forests and coral reefs and damage fish and other marine life.

Faster global warming

"This trend will only accelerate with the greenhouse effect," said Thomas Frolicher, a climate scientist at the University of Bern in Switzerland, who led the research.

His team defined marin heat waves as extreme events where the temperature of the seawater exceeded the 99th percentile of measurements for a given location.

Because oceans absorb and release heat at both slower and lower levels, most heat waves in the shipping industry persist for at least several days – and some for several weeks, Frolicher said.

"We knew that the average temperature was increasing, and what we have not concentrated on before is that the increase in the average comes to you in tunnels of very hot days – a shock of several days or weeks of very high temperatures, "said Michael Oppenheimer, a climate scientist at Princeton University who was not involved in the study.

Many zeecritters have evolved to survive within a fairly narrow band of temperatures compared to creatures on the land, and even the increasing heat can be disruptive.

Real danger

Some free-swimming marine animals, such as bat rays or lobsters, can shift their routines. But stationary organisms, such as coral reefs and kelp forests, "are in real danger," said Michael Burrows, an ecologist at the Scottish Marine Institute, who was not part of the research.

In 2016 and 2017, continuing high ocean temperatures in eastern Australia, as many as half of the shallow water cores of the Great Barrier Reef were killed, with significant consequences for other creatures dependent on the reef.

"One in four fish in the ocean lives in or around coral reefs," said Ove Hoegh-Guldberg, a marine biologist at the University of Queensland. "So much of the biodiversity of the ocean depends on a fairly small amount of the ocean floor."

The latest study in Nature was based on satellite data and other sea temperature data, including ships and buoys.

It did not include the recent record-breaking measurements of Scripps Pier in San Diego – which reached 46.4 degrees Celsius on August 9 – but Frolicher and Miller said the event was an example of a heat wave at sea.

Behavior of bat-rays

Miller said he knew something strange when he saw a school of bat-rays that usually only came in pockets of warm water near the pier earlier this month.

Changes in the ocean circulation associated with warmer surface waters are likely to mean reduced phytoplankton production – the small organisms that form the basis of the marine food web, he said.

Marine biologists nicknamed a patch of persistently high temperatures in the Pacific between 2013 and 2016 "the Blob." During this period, reduced phytoplankton production led to a gradual lack of food for many species, causing thousands of Californian sea lion pups to starve, said Miller, who had no role in the Nature study.

"We've repeatedly posted new heat records, but it's not surprising, but it's shocking," he said. – AP

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