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The EastAfrican
Date: 02.05.2016
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'Not enough oxygen
for marine life'
By CHRIS M00NEY
The Washington Post
IN THE long list of trou­
expand the number of areas
bling climate change sce­
sometimes called "oxygen
narios, there's one that gets minimum zones" where
relatively little attention,
plants, fish and other or­
but definitely has enormous ganisms would struggle to
survive.
potential consequences.
It goes like this: The
Now, in the new study,
oceans are getting warm­
Long and his colleagues
er. This raises the sea level
have found that some parts
and as a result reduces the of the ocean are already
amount of oxygen dissolved likely to be showing an oxy­
in the water.
gen deficiency, due to the
But it's worse: If surface
effects of global warming.
water is warmer, it doesn't
And by around 2030, the
mix down as much into the
human role in driving wide­
ocean depths any longer.
spread ocean oxygen loss
"What's happening is,
will be even more apparent
there's a physical mecha­
if greenhouse gas emissions
nism that impedes the de­
continue unchecked.
livery of surface waters into
"Its fairly widespread de­
the interior," said Matthew
tection....is basically evident
Long, an oceanographer
in the 2030s to 2040s dec­
with the National Centre
for Atmospheric Research
who is lead author of a trou­
ade," Long said.
And that could have ma­
lem. "A major concern is
that these so­called oxygen
minimum zones (OMZs)
will expand in the future
as the upper ocean warms
and becomes more strati­
fied," wrote the Scripps In­
stitution of Oceanography's
Ralph Keeling and two col­
leagues in 2010.
But what's new about
the current study is the use
of a sophisticated climate
change modeling process
to try to determine precise­
ly when a less oxygen­rich
ocean will manifest itself in
a way that can be attributed
to human­induced climate
change.
The new study thus aims
to solve this "signal­to­noise
problem," using a high­pow­
ered climate model that
couples together both the
atmosphere and ocean. The
authors ran multiple simula­
viable habitat for a host of
tions, starting in the year
organisms.
1920 and running through
The problem will be se­
the year 2100 — a key as­
vere in deeper waters of
co­authored with Curtis
sumption being that global
what the study calls the
Deutsch of the University of "ocean interior," which will
emissions remain at a high
Washington and Taka Ito
no longer receive as much of level throughout the cen­
of the Georgia Institute of
tury. This approach allowed
an exchange of oxygen­rich
Technology.
for a statistical detection of
waters with the surface.
The problem is that ma­
when ocean oxygen trends
Long's isn't the first re­
bling new study on what
scientists call the "deoxy­
genation" of the oceans.
The work appeared in Glo­
bal Biogeochemical Cycles,
rine life needs oxygen. If
there's less of it, that could
jor consequences for marine
organisms: A contraction of
port to warn of this prob­
move decisively downward
due to climate change.
If there's less of oxygen, that could expand the number of
areas sometimes called "oxygen minimum zones" where ocean
organisms would struggle to survive. Picture: AFP
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