Oxygen levels ‘falling 2 to 3 times faster than predicted’ in our warming oceans, study finds
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| Much of the ocean is seeing sharp drops in oxygen levels (purple). CREDIT: Georgia Tech |
Depletion
of dissolved oxygen in our oceans, which can cause dead zones, is
occurring much faster than expected, a new study finds.
And
by combining oxygen loss with ever-worsening ocean warming and
acidification, humans are re-creating the conditions that led to the
worst-ever extinction, which killed over 90 percent of marine life 252 million years ago.
Researchers at Georgia Institute of Technology reviewed
ocean data going back to 1958 and “found that oxygen levels started
dropping in the 1980s as ocean temperatures began to climb.”
Scientists
have long predicted that as carbon pollution warms the globe, the
amount of oxygen in our oceans would drop, since warmer water can’t hold
as much dissolved gas as colder water. And, Georgia Tech researchers
point out, falling oxygen levels have recently led to more frequent
low-oxygen events that “killed or displaced populations of fish, crabs
and many other organisms.”
But
what is especially worrisome about this new research is how quickly it
is happening. “The trend of oxygen falling is about two to three times
faster than what we predicted from the decrease of solubility associated
with the ocean warming,” said lead researcher Prof. Taka Ito. “This is
most likely due to the changes in ocean circulation and mixing
associated with the heating of the near-surface waters and melting of
polar ice.”
Global
warming drives ocean stratification — the separation of the ocean into
relatively distinct layers. This in turn speeds up oxygen loss, as
explained in this 2015 video.
A 2011 study,
“Rapid expansion of oceanic anoxia immediately before the end-Permian
mass extinction,” found that rapid and widespread anoxia (absence of
oxygen) preceded “the largest mass extinction in Earth history, with the
demise of an estimated 90 percent of all marine species.”
As National Geographic reported in 2015, we’re already starting to see
the impacts of anoxia. “The waters of the Pacific Northwest, starting
in 2002, intermittently have gotten so low in oxygen that at times
they’ve smothered sea cucumbers, sea stars, anemones, and Dungeness
crabs,” the magazine reported.
Finally, a 2015 study found
there is no techno-fix to prevent a catastrophic collapse of ocean life
for centuries if not millennia if we continue current CO2 emissions
trends through 2050.
If
we don’t start slashing carbon pollution, then, as co-author John
Schellnhuber put it, “we will not be able to preserve ocean life as we
know it.”
Links
- Climate change and overfishing are driving the world’s oceans to the ‘brink of collapse’
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- America’s tragic fall from international climate leader to global embarrassment
- Trump’s biggest reason for leaving the Paris agreement is based on a myth
- Climate change is already forcing U.S. communities to abandon their homes
- Climate change poses ‘nightmare scenario’ for Florida coast, Bloomberg warns
- Big Coal wants Trump to sabotage the Paris climate deal from the inside
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