From Mother Jones · Jim Robbins · · 3m
The ocean is running a fever, and it's rewriting who lives where
Octopus swarms off England, dead cormorants on California beaches, and 82 percent of the world's oceans running hot at once.
In brief
Octopus swarms off England, dead cormorants on California beaches, and 82 percent of the world's oceans running hot at once. Marine heat waves hit too fast for sea life to adapt, and the damage from the last one is still unhealed when the next arrives. Originally reported by Mother Jones.
Octopus arrived by accident
Common octopus larvae normally die when they drift from the Mediterranean into cold Channel water. Last year they hitched a ride on plankton to England's coast and lived.
Biggest bloom in 75 years
A heat wave off Devon and Cornwall pushed water up to 9 degrees F above normal, and the octopus bloom became the largest since 1950.
Winners and losers
UK octopus landings ran about 7,700 percent above normal, a windfall for fishers. Scallop, lobster and crab catches collapsed.
New predators moved in
Seals, conger eels and dolphins fattened on octopus. Bluefin tuna and sharks returned to British waters for the first time in decades.
“It has completely shaken up the food chain.”
This time they don't die
Past octopus surges ended when cold water returned and killed them off. Researcher Bryce Stewart says these octopuses are not dying, they are breeding.
Most of the ocean is hot
About 82 percent of the world's oceans are in a marine heat wave right now, and this year set new temperature records.
What a heat wave does
Ocean fevers push fish deeper, bleach coral, trigger mass die-offs, feed algal blooms, and fuel storms that wreck fishing and tourism.
The oceans took the heat
A heat wave means five straight days above the 90th percentile of normal. Oceans have soaked up more than 90 percent of the excess heat humans have added.
Slow warming, sudden shock
Gradual warming gives species time to adapt. Heat waves are acute and leave almost none. Since 1940, days of extreme surface heat have tripled.
The Pacific's giant
The world's largest marine heat wave now sprawls across more than 24 million square miles of Pacific, and a record El Nino is expected to push two more off California.
How the Blob formed
In late 2013 a stubborn high-pressure ridge stalled the winter winds that cool the eastern Pacific. The sun did the rest. By 2014 waters ran 7 degrees F above average.
The krill vanished
In 2015 Ric Brodeur pulled up nets he expected to be full of krill, the base of the food chain, and found almost nothing.
“You could fit all the krill from the trip into a little plastic bag.”
Seven thousand whales gone
North Pacific humpbacks fell by about 20 percent. Emaciated females lost calves, and the reproductive slump ran until 2021, five years past the Blob's end.
Underwater rainforests fell
Kelp died from Baja to British Columbia, with 95 percent wiped out in Northern California. Red abalone crashed so hard the fishing ban now runs to 2036.
“It has a specific temperature threshold where it falls apart and it can't survive.”
Four million murres starved
Warm currents scattered the anchovies and sardines that Alaska's common murres eat. Half the population died, and a 2024 study found no sign of recovery.
A new Blob is here
Dying pelicans and cormorants are washing up in Southern California, and a record toxic algal bloom stretches to British Columbia. Scripps says heat wave days now match 2015 exactly.
“We are definitely along the same trend now. This is a new Blob.”
The bottom line
Marine heat waves hit too fast for sea life to adapt, and the damage from the last one is still unhealed when the next arrives.
