A team of scientists, in a groundbreaking analysis of data from hundreds of sources, has concluded that humans are on the verge of causing unprecedented damage to the oceans and the animals living in them, The New York Times reports.
“We may be sitting on a precipice of
a major extinction event,” said Douglas J McCauley, an ecologist at the
University of California, Santa Barbara, and an author of the new research,
which was published on Thursday in the journal Science.
But there is still time to avert
catastrophe, Dr McCauley and his colleagues also found. Compared with the
continents, the oceans are mostly intact, still wild enough to bounce back to
ecological health.
“We’re lucky in many ways,” said
Malin L Pinsky, a marine biologist at Rutgers University and another author of
the new report.
“The impacts are accelerating, but
they’re not so bad we can’t reverse them.”
Scientific assessments of the
oceans’ health are dogged by uncertainty: It’s much harder for researchers to
judge the well-being of a species living underwater, over thousands of miles,
than to track the health of a species on land. And changes that scientists
observe in particular ocean ecosystems may not reflect trends across the
planet.
Dr
Pinsky, Dr McCauley and their colleagues sought a clearer picture of the
oceans’ health by pulling together data from an enormous range of sources, from
discoveries in the fossil record to statistics on modern container shipping,
fish catches and seabed mining. While many of the findings already existed,
they had never been juxtaposed in such a way.
A
number of experts said the result was a remarkable synthesis, along with a
nuanced and encouraging prognosis.
“I
see this as a call for action to close the gap between conservation on land and
in the sea,” said Loren McClenachan of Colby College, who was not involved in
the study.
There
are clear signs already that humans are harming the oceans to a remarkable
degree, the scientists found. Some ocean species are certainly overharvested,
but even greater damage results from large-scale habitat loss, which is likely
to accelerate as technology advances the human footprint, the scientists reported.
Coral
reefs, for example, have declined by 40 percent worldwide, partly as a result
of climate-change-driven warming.
Some
fish are migrating to cooler waters already. Black sea bass, once most common
off the coast of Virginia, have moved up to New Jersey. Less fortunate species
may not be able to find new ranges. At the same time, carbon emissions are
altering the chemistry of seawater, making it more acidic.
“If
you cranked up the aquarium heater and dumped some acid in the water, your fish
would not be very happy,” Dr Pinsky said. “In effect, that’s what we’re doing
to the oceans.”
Fragile
ecosystems like mangroves are being replaced by fish farms, which are projected
to provide most of the fish we consume within 20 years. Bottom trawlers
scraping large nets across the sea floor have already affected 20 million
square miles of ocean, turning parts of the continental shelf to rubble. Whales
may no longer be widely hunted, the analysis noted, but they are now colliding
more often as the number of container ships rises.
Mining
operations, too, are poised to transform the ocean. Contracts for seabed mining
now cover 460,000 square miles underwater, the researchers found, up from zero
in 2000. Seabed mining has the potential to tear up unique ecosystems and
introduce pollution into the deep sea.
The
oceans are so vast that their ecosystems may seem impervious to change. But Dr
McClenachan warned that the fossil record shows that global disasters have
wrecked the seas before.
“Marine
species are not immune to extinction on a large scale,” she said.
Until
now, the seas largely have been spared the carnage visited on terrestrial
species, the new analysis also found.
The
fossil record indicates that a number of large animal species became extinct as
humans arrived on continents and islands. For example, the moa, a giant bird
that once lived on New Zealand, was wiped out by arriving Polynesians in the
1300s, probably within a century.
But
it was only after 1800, with the Industrial Revolution, that extinctions on
land really accelerated.
Humans
began to alter the habitat that wildlife depended on, wiping out forests for
timber, ploughing under prairie for farmland, and laying down roads and
railroads across continents.
Species
began going extinct at a much faster pace. Over the past five centuries,
researchers have recorded 514 animal extinctions on land. But the authors of
the new study found that documented extinctions are far rarer in the ocean.
Before 1500, a few species of
seabirds are known to have vanished. Since then, scientists have documented
only 15 ocean extinctions, including animals such as the Caribbean monk seal
and Steller’s sea cow.
While these figures are likely
underestimates, Dr McCauley said that the difference was nonetheless revealing.
“Fundamentally, we’re a terrestrial
predator,” he said. “It’s hard for an ape to drive something in the ocean
extinct.”
Many marine species that have become
extinct or are endangered depend on land — seabirds that nest on cliffs, for
example, or sea turtles that lay eggs on beaches.
Still, there is time for humans to
halt the damage, Dr McCauley said, with effective programs limiting the
exploitation of the oceans. The tiger may not be salvageable in the wild — but
the tiger shark may well be, he said.
“There are a lot of tools we can
use,” he said. “We better pick them up and use them seriously.”
Dr McCauley and his colleagues argue
that limiting the industrialization of the oceans to some regions could allow
threatened species to recover in other ones. “I fervently believe that our best
partner in saving the ocean is the ocean itself,” said Stephen R Palumbi of
Stanford University, an author of the new study.
The scientists also argued that
these reserves had to be designed with climate change in mind, so that species
escaping high temperatures or low pH would be able to find refuge.
“It’s creating a hopscotch pattern
up and down the coasts to help these species adapt,” Dr Pinsky said.
Ultimately, Dr Palumbi warned,
slowing extinctions in the oceans will mean cutting back on carbon emissions,
not just adapting to them.
“If by the end of the century we’re
not off the business-as-usual curve we are now, I honestly feel there’s not
much hope for normal ecosystems in the ocean,” he said. “But in the meantime,
we do have a chance to do what we can. We have a couple decades more than we
thought we had, so let’s please not waste it.”
Read the article HERE.
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