In the great halls of La
Boqueria, Barcelona’s central market, tourists, foodies and cooks gather
every day to marvel at the fresh food, like pilgrims at the site of a
miracle.
The chief shrines are the fish counters, where thousands of sea
creatures making up dozens of species gleam pink and gray on mounds of
ice.
But to many ocean scientists this is not a display of the ocean’s
bounty but a museum—by the end of this century, many of these animals may be history
due to man’s reckless abuse of the planet.
As we keep dumping
greenhouse gases into the air, the oceans keep sucking them up, making
the waters deadly to their inhabitants.
On the
Boqueria’s fish stands I count 10 types of bivalves—creatures like
clams, oysters and mussels that use calcium carbonate to make their
endlessly varied shells.
In as little as 20 years they will be very
different and, in some parts of the world, entirely gone.
Then there are
the ranks of huge Asian prawns and tiny shrimps, terra-cotta crabs from
Scotland, and lobsters, magnificent admirals in blue fringed with gold.
Lucky for them, these creatures make their shells differently (mostly
out of a polymer called chitin), so the rapidly acidifying waters of our
oceans won’t dissolve them as it will the exteriors of the bivalves.
But the acidification—which some scientists believe is the fastest change in the ocean’s chemistry in 300 million years—appears to harm the working of the gills and change the behavior of the crustaceans when they are very young.
On the crushed ice sit a dozen kinds of finned
creatures that the Spanish love—monkfish, hake, sardines, tuna.
The
Spaniards eat more fish than anyone else in Europe.
The effect of
changing ocean chemistry on fish health, longevity and reproduction is
not yet certain.
But even now, many species on the Boqueria stalls are
also on one or more European “at-risk” lists: under threat because of
overfishing or changes in the chain of foods that supply them, or from
the bigger threat of the changing ocean biogeochemistry.
The
last is the least understood of these phenomena.
Along the coasts and
out in the deep, huge “dead zones” have been multiplying.
They are the
emptiest places on the planet, where there’s little oxygen and sometimes
no life at all, almost entirely restricted to some unicellular
organisms like bacteria.
Vast blooms of algae—organisms that thrive in
more acid (and less alkaline) seawater and are fed by pollution—have
already rendered parts of the Baltic Sea pretty much dead.
A third of
the marine life in that sea, which once fed all of Northern Europe, is
gone and may already be beyond hope of recovery.
“There’s
a profound game-changing event going on in the life of the sea,” says
Callum Roberts, a professor of marine conservation at the University of
York, England.
“The fact is that changes in alkalinity are going to
cause massive reorganization of marine life, impacts on marine food
webs, productivity, all sorts of things. We’re heading for a car crash
here.”
Many of these risks are caused by one of the world’s most pressing problems: climate change.
Rising greenhouse gases
in the atmosphere are causing global temperatures to rise, which is
leading to the melting of the polar ice caps, which in turn has resulted
in rising sea levels and a host of ecological issues.
It’s also causing the chemical makeup of the
world’s oceans to change so rapidly.
Carbon dioxide, one of the key
perpetrators in the lineup of man-made greenhouse gases, is absorbed by
seawater, causing a chemical reaction near the ocean surface that results in lowered pH levels.
And about one-third
of all the man-made carbon dioxide released into the atmosphere ends up
absorbed by the oceans.
Carles Pelejero, a scientist working less than a
mile from La Boqueria at the Institut de Cienciès del Mar (ICM), on
Barcelona’s seafront, calls it “climate change’s evil twin.”
He
illustrates the basic mechanism to schoolchildren by getting them to
take a straw and blow into a glass of water.
A simple litmus test shows
the children how the pH level drops as the carbon dioxide from their
breath dissolves in the water.
It’s a sign that naturally alkaline water
is becoming less so—and it’s what is happening on a global scale as the
oceans absorb a significant amount of the carbon dioxide we pump out
through the burning of carbon fuels.
“In preindustrial times the ocean’s
pH was 8.2. It has already gone down to 8.1,” says Pelejero. “Depending
on what we do, it will reach an average of 7.8 or 7.7 by 2100. It
hasn’t been that low for 55 million years.”
For reference, the pH scale
runs from 0 to 14; the lower the number the more acidic, and the higher
the more alkaline.
Pelejero leads part of the ICM’s
marine biogeochemistry research, but his field is even more specific:
marine paleo-reconstruction.
You might call it seabed archaeology; it
uses drills to take samples from deep in the sediment at the bottom of
the ocean.
Scientists can use those samples to work out how the
geochemistry of sea creatures has changed over the millennia.
Pelejero
started in this business in the mid-1990s using the remains of plankton
in the sediments on the ocean floor to determine historic sea surface
temperatures.
Then, in 1998, while studying a graph at a
conference, Joanie Kleypas, an American biologist working on coral
reefs, had a eureka moment.
When she suddenly realized that the lowered
alkalinity at the end of the 21st century would in effect corrode the
calcium carbonate foundation of the reefs to destruction, she was so
horrified she left the room to be sick.
Her paper on the threat, published in the journal Science in
1999, was an alarm call.
Other scientists quickly dubbed the effect
“ocean acidification”—although the seas would not actually turn to acid,
the phrase, they reckoned, would emphasize the urgency and get action.
Coral reefs are necessary to an estimated 25 percent of all marine life,
including 4,000 species of fish.
They are the rain forests of the sea.
Around
the same time, Pelejero’s colleagues turned their core-sampling
techniques to work out how the ocean and its animals behaved long ago,
when the water pH was lower.
What they found was horrifying.
During a
100,000-year-long event known as the Palaeo-Eocene Thermal Maximum
(PETM), which occurred between the Palaeo and Eocene epochs, 55 million
years ago, “you see that the sediment is quite white from the fossil
shells—then suddenly it turns red,” Pelejero says.
“Because there are no
shells at all. Then it turns white again—but the change back took more
than 100,000 years.”
The first change from white to red represents a
sudden die-off of shell-based life; the turn back to white shows the
gradual return of shellfish over time.
If projections hold, the pH
change that killed off or radically altered many of the deep ocean shell
animals will arrive again at the end of this century.
Other
problems are likely to emerge because of the pH change.
One of the
suggestions is that the stable, solid form of methane—called
clathrates—that lurks in the ocean sediment may be upset by changes in
water chemistry and temperature, and release the gas into the
atmosphere.
Methane is a greenhouse gas many times more damaging than
carbon dioxide, which has, in the past, turbocharged global warming.
This is called the “clathrate gun hypothesis,” and the core samples
suggest that this is just what might have happened during the PETM, when
large numbers of ocean species (particularly from the deeps of the
seas) disappeared and the ocean surface was 9 to 16 degrees Fahrenheit
warmer. That doesn’t sound like much.
But it’s enough to radically alter
life underwater—and to wreak havoc on land dwellers, too.
Many of the
world’s major cities would disappear beneath the rising waves as the ice
melts and the water expands.
During the PETM, sea levels were as much
as 350 feet higher than they are today—enough to obliterate most of
present-day Europe, the northeast coast of the U.S. and Argentina, for
example.
What worries Pelejero most is the rapidity of
today’s changes.
The same shifts that happened over the course of a few
thousand years during the PETM are now due to happen over just a few
centuries, counting from the beginning of the Industrial Revolution and
the widespread use of fossil fuels.
“The record tells us that, though pH
has been lower in the past, this time the changes are happening about
10 times faster. And that means there is no time for species to evolve
and adapt, or the ocean to buffer itself,” Pelejero says.
“It’s clear
that the ocean is acidifying, much clearer than that the world is
warming. And we know that most of the effect is caused by man’s actions.
The only argument among scientists is over how much damage is being
done.”
Already some effects are being seen.
Across the world, shells of some animals are thinner
than they were 300 years ago.
An acidification spike around the coast
of British Columbia in February 2014 wiped out 10 million scallops.
Foraminifera, the tiniest shelled plankton in the ocean, are having trouble growing
(as they did during the PETM)—and plankton is the food base of every
animal in the sea.
Coccolithophores, the shelled plankton that process
sunlight like a plant, and whose remains built the White Cliffs of
Dover, seem to suffer from current changes in ocean chemistry.
Pteropods,
tiny swimming snails, are the main diet of cold-water fish most
commonly consumed in both Europe and North America—salmon, haddock, cod
and pollack.
In the lab, pteropods dissolve in lowered alkali waters,
like a tooth in Coca-Cola.
In the Arctic, where acidification is
progressing fastest, pteropods may already be on the way out. It is as
though the Earth were losing its grass, and the cows had nothing to eat.
Rising Tides Kill All
A
day after visiting the fish markets, I lounged on the deck of a tiny
former fishing boat off the northern Catalan coast, as oceanologists
threw up into the lurching waves around us.
We were off to take ICM’s
monthly water samples.
The boat is skippered by a
remarkable man, 63-year-old Josep Pascual, a legend around the fishing
ports of the Costa Brava.
As a boy, he went out in this boat with his
father and grandfather to net fish for the market.
“I used to listen to
them, talking as fishermen do about the weather and the sea temperature,
and I got interested.”
He decided to add some hard
data to the family debate.
So since the mid-1960s he has been building
his own instruments, and taking a daily record of sea temperatures at
different depths in the Mediterranean current off the fishing port of
Estartit, Spain.
In that little harbor there’s a box containing an
ingenious gadget attached to the seawall that measures the height of the
sea.
“I built it from parts that were thrown out of the old
meteorological station,” Pascual says.
“I’d read in a book that there
were no tides in the Mediterranean—I wanted to prove that was wrong.”
He
succeeded, and he has also shown that the average sea level in the
Mediterranean has risen about 3.5 inches over the past 24 years.
That is
in line with the global calculations of melting ice cover made by
climate change scientists.
The rising sea levels, of course, are caused
by greenhouse gases in the atmosphere—which are also what’s causing
acidification.
Pascual’s work came to the attention of
the ICM in the early 1970s.
Ever since then, ICM and Pascual have worked
together.
The fishing nets and lines on the Fiera del Mar are now
replaced by global positioning systems, depth-measuring tools and
complex thermometer instruments.
They have done this long enough to
prove significant warming of the Costa Brava sea.
Seven
years ago, sponsored chiefly by the Catalan and Spanish governments,
Pascual, Pelejero and their assistants started making monthly trips to
measure the ocean’s acidity.
These have yet to produce conclusive
results—there hasn’t yet been enough time to confirm the clear drop in
pH that has been observed out in the open oceans.
Pascual
is a smiling, sea-worn man, his nut-brown face in sharp contrast to the
biochemists’ laboratory pallor.
I ask what he really thinks is going
on.
“What I’m shocked by most is the rising sea level—and I am convinced
this is caused by climate change, and that it is mankind that has done
it,” he says.
“It’s worrying, because the oceans are so important in
capturing the carbon. They thermo-regulate the planet. These changes in
their systems are very big, and they should make us worry.”
Algae bloom in the Bay of Biscay. ESA
Into the Dead Zone
Off
the desert coast of Oman last winter, I saw the strangest thing I’d
ever seen in a lifetime of sea voyaging.
Heading in a rigid inflatable
boat toward a snorkeling site, my family and I all gasped suddenly as
the creamy-white of the wake turned a virulent, toxic-looking green.
It
had an ammoniac stink, and it stayed that way for the next mile.
“No
farming nearby? River estuaries?” asked Esther Garcés, a marine
biologist at ICM, when I told her this story.
None.
The Omani coast I
saw was mountain and desert.
“Probably a normal, seasonal phytoplankton
bloom.”
She showed me spectacular pictures, taken from a
European Space Agency satellite, of a green-blue swirl occupying most
of the Bay of Biscay, between western France and northern Spain.
Garcés’s specialty is harmful blooms of algae and plankton: She makes
weekly risk assessments for the whole of the Catalan coast.
The chief
issue is their potential harm to shellfish farms—when the bivalves eat
the algae, the former can become toxic to humans who consume them later.
(Less pressing is the fact that they make the tourist beaches look as
if they are covered in green slime.)
All such blooms are
on the increase, mostly due to pollution from humans on land.
Sewage,
extra carbon in the atmosphere and the runoff of artificial fertilizers
all feed different plankton forms, making the blooms fantastically big.
Human tampering with the shape of the coast can create vast areas away
from the waves where the algae can peacefully breed.
The
21st century’s algae can have adverse effects far beyond weird-colored
water and a smell.
The key problems come when plankton die.
“The toxins
released kill fish and other marine life,” says Garcés, “and then
there’s the problem of hypoxia and dead zones.”
As the algae blooms die
out, the matter that drops from the blooms to the bottom of the ocean
eats oxygen as it decomposes (with the help of the bacteria that feed on
the dead plankton), and hypoxic (low oxygen) and anoxic (total
depletion of oxygen) zones kill everything that needs oxygen to live.
Dead
zones move and fluctuate, so they are hard to measure.
Oceanographers
believe they have increased exponentially since the 1960s, and now count
over 400 across the globe.
One of the world’s largest is off the
Mississippi Delta, caused by algae blooms fed mainly by excess chemical
fertilizers spread over the land through which the Mississippi flows.
Though it changes from year to year, the Mississippi Delta dead zone has
been recorded as large as 8,000 square miles, roughly the size of New Jersey.
Scientists diving in it are quoted by Roberts, in his book Ocean of Life:
“As you go deeper, it gets kind of scary. Because there’s nothing
there. There’s no fish, no organisms alive, so it’s just us.”
The
Mississippi Delta zone is the world’s second biggest coastal hypoxic
area, after the Black Sea.
But out in the open oceans, hundreds of feet
below the surface, there are dead zones so huge they may be bigger than
the Sahara Desert—the largest lifeless spaces this side of the moon.
There
are three different forces that create zones where there's so little
oxygen that most life forms disappear.
“Upwellings” in parts of the
ocean are natural, caused by ocean currents or undersea seismic
activity.
Periodically they bring nutrients and phytoplankton (a group
of plankton that use sunlight for energy) to the surface.
In sunlight
this mass feeds on algae blooms, until it dies and the bacteria thrive
in their turn, eating the dead plankton and absorbing more oxygen.
The
Black Sea is stagnant and dead from about 500 feet below its warm
surface because of its natural geological structure, and the fact that
there are few currents to mix up the oxygen-rich surface with the dark,
highly acidic waters below.
But a crucial sea for human food, the
Baltic, has died because of the mess humans make.
Algae blooms have been a feature of the Baltic
since the 19th century, initially because nutrient-filled soil ran off
as the native forest was cut down to fuel the industries and build the
cities of Northern Europe.
Then more plankton food was added by the
runoff of pollution from the busy Baltic coastline (which includes major
cities like St. Petersburg, Russia; Copenhagen, Denmark; Stockholm;
Riga, Latvia; and Helsinki) as well as slurry from the industrialized
pig farms that are a major business in parts of Germany and Denmark.
Now
much of the seabed is covered in life-choking seaweed (a multicellular
type of algae), and fish eggs from species like cod cannot survive in
the low-oxygen environment.
“The Nordic people have
made a huge effort to control the runoff of nutrients into the Baltic,”
says Garcés.
“But it is too late. The nutrients don’t go away. Every
time the organisms grow they die and go back to the bottom again, eating
more oxygen. Biodiversity is like a dictionary, and this process in the
ecosystem is like losing words. We cannot get them back.”
Jellyfish
No Fish for You
The one thing that the Boqueria fishmongers doesn’t sell is jellyfish (there’s not much demand for them in Spain, or anywhere else in Europe), though you can find them, dried to a plastic scab, in some Chinese supermarkets.
There are those who say that
jellyfish and plankton are all that your average wild seafood eater will
have for supper by the end of the century—the very rich will likely
still be able to pay up for ultra-rare food items.
That’s because as the
food chain’s intricate links collapse, the complex species will go
first, leaving only the most simple.
“The oceans [will] revert to the
earliest days of multicellular life,” Roberts drily puts it.
There’s a
terrifying argument that jellyfish—who rather enjoy acidification—are already taking over the seas, if not the world.
The
answers are not easy.
Some of the clever “geoengineering” suggestions
offered to tackle global warming—like artificially cutting off
sunlight—won’t work for the oceans, because we can’t just incrementally
slow down the acidification — we have to remove the excess carbon
dioxide that’s already out there in the atmosphere.
Doing that takes
economically painful initiatives—replanting vast areas of forest to
recapture carbon, for example, and, above all, simply stopping the
burning of fossil fuels.
There are some causes for
hope.
Some world leaders are beginning to take these threats more
seriously.
In June, for example, the Obama administration announced
a series of measures aimed to conserve the ocean as a key food supply
for more than 3 billion of us.
These included more ocean sanctuaries to
curtail overfishing, and new funds to research ocean biochemistry,
including acidification.
Roberts, for his part, says
that he has been happy to see that coral reefs have proved more
adaptable—faster and faster at recovering from the effects of acid and
ozone layer depletion—than scientists previously thought.
Recent
research suggests than in the more acidic waters predicted for the late
21st century, the reefs may survive a little better than Kleypas and her
colleagues originally expected.
“That’s got to be cause for
hope,” says Roberts.“But these are isolated instances—they say life is possible in these altered environments, they don’t say that means species will thrive in 2100. Evidence from around the world is that they will not. We have the loss of one of the world’s major habitats on the cards. It’s already happening.”
Links :
- Global Ocean Commission : Five-year Ocean Rescue Package
- NYTimes : Obama Plans Protected Marine Area in Pacific Ocean
