This story was originally published by Yale Environment 360 and is reproduced here as part of the Climate Desk collaboration.
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story → publish → collaboration
The common octopus is a warm water species that usually lives in the temperate waters of the Mediterranean.
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that → live → Mediterranean
But last year, octopus larvae hitchhiked across the English Channel attached to plankton, resulting in an octopus bloom off England’s coast.
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larvae → hitchhike → coast
Normally, octopus larvae that drift into cold waters die.
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that → drift → waters
But this year’s bloom, experts say, is the result of an unusually intense marine heat wave off of Devon and Cornwall, which raised water temperatures up to 9 degrees F above normal.
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which → say → normal
The change in species has been a boon for local fishers selling octopus into the lucrative European export market.
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change → sell → market
And while the invasion has slashed the catch of scallops, lobster, and crab, it has boosted numbers of seals, conger eels, and dolphins, which eat octopus.
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which → slash → octopus
The warming, in combination with abundant prey, has also drawn bluefin tuna and sharks to British waters for the first time in decades.
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warming → warm → decades
“It has completely shaken up the food chain,” said Bryce Stewart, a senior research fellow at the UK’s Marine Biological Association, which has been studying the phenomenon.
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which → shake → phenomenon
While this kind of bloom has happened here before, he said, this one is different.
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one → happen → bloom
During past surges, the return of cold water killed off the octopuses.
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return → kill → octopuses
This time, the octopuses aren’t dying.
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octopuses → die → ?
They’re reproducing.
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They → reproduce → ?
And the heat wave continues.
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wave → continue → ?
Globally, marine heat waves—prolonged periods of unusually warm water—are becoming more common, more intense, longer lasting, and more widespread, experts say.
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experts → become → water
This year, ocean heat is unusually severe, setting new temperature records.
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heat → set → records
According to Global Climate Risks, a nonprofit created by scientists to publicize the effects of climate change, an estimated 82 percent of the world’s oceans are currently experiencing marine heat waves.
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percent → accord → waves
Evidence from recent hot spells suggests the impacts on sea life could be profound and long-lasting.
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impacts → suggest → life
Ocean fevers can rearrange marine ecosystems, drive fish to move into deeper, colder layers of the sea, trigger coral bleaching, and cause widespread marine die-offs.
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fevers → rearrange → offs
They can increase the severity and number of algal blooms, which harm fish, shellfish, marine mammals, and birds.
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which → increase → fish
And they can cause extreme weather events, like tropical storms and hurricanes, and upend fishing and tourism.
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they → cause → fishing
To officially be called a heat wave, temperatures must rise above the 90th percentile of normal seasonal variation for five consecutive days.
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temperatures → call → days
While marine heat waves do occur naturally, climate scientists say anthropogenic warming has exacerbated them.
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warming → occur → them
According to NOAA scientists, oceans have absorbed more than 90 percent of the excess heat produced by human-caused global warming.
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oceans → accord → warming
One recent study found that, since 1940, warming has led to a threefold increase in the number of days per year with extreme heat at the ocean surface.
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warming → find → surface
Ocean warming is gradual and allows more time for species to adapt and evolve.
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species → allow → time
Marine heat waves are acute and produce rapid and extreme changes that give organisms little time to adapt.
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that → produce → time
But the long-term warming trend is making ocean heat more severe.
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heat → make → ?
Climate change has raised the temperature of the waters off the UK by around 2 degrees F above average in the last six decades, worsening this year’s record heat.
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change → raise → heat
Records have fallen elsewhere in Europe as well.
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Records → fall → Europe
“We find it’s the most extreme July marine heat wave conditions for the Western Mediterranean, the Celtic Region, and for the Bay of Biscay and Iberian Peninsula,” said Catherine Gregory, a climate scientist at the University of Bern.
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Gregory → find → Bern
The Pacific has warmed in northern regions by almost 2 degrees F and is currently experiencing the world’s largest marine heat wave, which sprawls over more than 24 million square miles.
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which → warm → miles
And in the central and eastern Pacific, things are bound to get worse.
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things → bind → Pacific
This year’s El Niño is expected to be the strongest in living memory—it has already spiked sea temperatures far earlier in the year than expected—and scientists fear it will expand the size and intensity of the two existing marine heat waves off the California coast.
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it → expect → coast
Based on studies of past heat waves—in particular, an event known as the Blob, the largest marine heat wave on global record, which dramatically raised temperatures in the eastern Pacific between 2014 and 2016—scientists are warily watching the warming ocean, anticipating a cascade of severe impacts both onshore and off.
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scientists → base → impacts
The Blob began to form in the fall of 2013, when a persistent high-pressure ridge greatly reduced the cool winter winds that normally blow over the eastern Pacific.
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that → begin → Pacific
Without that cooling, the sun created a very large body of very warm water.
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sun → cool → water
In 2014, ocean temperatures were 7 degrees F above average, and the cold, nutrient-rich water that normally coursed along the West Coast disappeared.
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that → course → Coast
In 2015, researcher Ric Brodeur was monitoring populations of shrimp-like krill, which form the base of the marine food chain, expecting his sampling nets to be full.
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nets → monitor → chain
“You could fit all the krill from the trip into a little plastic bag,” he said.
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he → fit → bag
…and 33 more, not listed.
