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Triona McGrath: How pollution is changing the ocean's chemistry
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As we keep pumping carbon dioxide into the atmosphere, more of it is dissolving in the oceans, leading to drastic changes in the water's chemistry. Triona McGrath researches this process, known as ocean acidification, and in this talk she takes us for a dive into an oceanographer's world. Learn more about how the "evil twin of climate change" is impacting the ocean -- and the life that depends on it.
Triona McGrath - Chemical oceanographer
Triona McGrath researches how the oceans are changing due to human activities. Full bio
Triona McGrath researches how the oceans are changing due to human activities. Full bio
Double-click the English transcript below to play the video.
00:13
Do you ever think about how important
the oceans are in our daily lives?
the oceans are in our daily lives?
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The oceans cover two-thirds of our planet.
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They provide half the oxygen we breathe.
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They moderate our climate.
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And they provide jobs
and medicine and food
and medicine and food
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including 20 percent of protein
to feed the entire world population.
to feed the entire world population.
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People used to think
that the oceans were so vast
that the oceans were so vast
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that they wouldn't be affected
by human activities.
by human activities.
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Well today I'm going to tell you
about a serious reality
about a serious reality
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that is changing our oceans
called ocean acidification,
called ocean acidification,
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or the evil twin of climate change.
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Did you know that the oceans have absorbed
25 percent of all of the carbon dioxide
25 percent of all of the carbon dioxide
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that we have emitted to the atmosphere?
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Now this is just another great service
provided by the oceans
provided by the oceans
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since carbon dioxide
is one of the greenhouse gases
is one of the greenhouse gases
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that's causing climate change.
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01:13
But as we keep pumping
more and more and more
more and more and more
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carbon dioxide into the atmosphere
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more is dissolving into the oceans.
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And this is what's changing
our ocean chemistry.
our ocean chemistry.
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When carbon dioxide dissolves in seawater,
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it undergoes a number
of chemical reactions.
of chemical reactions.
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Now lucky for you,
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I don't have time to get into
the details of the chemistry for today.
the details of the chemistry for today.
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01:37
But I'll tell you as more
carbon dioxide enters the ocean,
carbon dioxide enters the ocean,
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the seawater pH goes down.
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And this basically means that there
is an increase in ocean acidity.
is an increase in ocean acidity.
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And this whole process
is called ocean acidification.
is called ocean acidification.
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And it's happening
alongside climate change.
alongside climate change.
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Scientists have been monitoring
ocean acidification for over two decades.
ocean acidification for over two decades.
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This figure is an important
time series in Hawaii,
time series in Hawaii,
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and the top line shows steadily increasing
concentrations of carbon dioxide,
concentrations of carbon dioxide,
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or CO2 gas, in the atmosphere.
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And this is directly as a result
of human activities.
of human activities.
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The line underneath shows the increasing
concentrations of carbon dioxide
concentrations of carbon dioxide
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that is dissolved
in the surface of the ocean
in the surface of the ocean
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which you can see is increasing
at the same rate
at the same rate
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as carbon dioxide in the atmosphere
since measurements began.
since measurements began.
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The line on the bottom shows
then shows the change in chemistry.
then shows the change in chemistry.
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As more carbon dioxide
has entered the ocean,
has entered the ocean,
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the seawater pH has gone down,
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which basically means there has been
an increase in ocean acidity.
an increase in ocean acidity.
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Now in Ireland, scientists are also
monitoring ocean acidification --
monitoring ocean acidification --
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scientists at the Marine
Institute and NUI Galway.
Institute and NUI Galway.
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And we, too, are seeing
acidification at the same rate
acidification at the same rate
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as these main ocean time-series
sites around the world.
sites around the world.
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So it's happening right at our doorstep.
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Now I'd like to give you an example
of just how we collect our data
of just how we collect our data
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to monitor a changing ocean.
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Firstly we collect a lot of our samples
in the middle of winter.
in the middle of winter.
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So as you can imagine,
in the North Atlantic
in the North Atlantic
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we get hit with some seriously
stormy conditions --
stormy conditions --
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so not for any of you
who get a little motion sickness,
who get a little motion sickness,
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but we are collecting
some very valuable data.
some very valuable data.
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So we lower this instrument
over the side of the ship,
over the side of the ship,
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and there are sensors
that are mounted on the bottom
that are mounted on the bottom
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that can tell us information about
the surrounding water,
the surrounding water,
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such as temperature
or dissolved oxygen.
or dissolved oxygen.
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And then we can collect our seawater
samples in these large bottles.
samples in these large bottles.
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So we start at the bottom,
which can be over four kilometers deep
which can be over four kilometers deep
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just off our continental shelf,
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and we take samples at regular intervals
right up to the surface.
right up to the surface.
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We take the seawater back on the deck,
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and then we can either
analyze them on the ship
analyze them on the ship
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or back in the laboratory
for the different chemicals parameters.
for the different chemicals parameters.
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But why should we care?
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How is ocean acidification
going to affect all of us?
going to affect all of us?
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Well, here are the worrying facts.
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There has already been an increase
in ocean acidity of 26 percent
in ocean acidity of 26 percent
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since pre-industrial times,
which is directly due to human activities.
which is directly due to human activities.
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Unless we can start slowing down
our carbon dioxide emissions,
our carbon dioxide emissions,
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we're expecting an increase
in ocean acidity of 170 percent
in ocean acidity of 170 percent
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by the end of this century.
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I mean this is within
our children's lifetime.
our children's lifetime.
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This rate of acidification
is 10 times faster
is 10 times faster
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than any acidification in our oceans
for over 55 million years.
for over 55 million years.
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So our marine life have never,
ever experienced
ever experienced
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such a fast rate of change before.
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So we literally could not know
how they're going to cope.
how they're going to cope.
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Now there was a natural acidification
event millions of years ago,
event millions of years ago,
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which was much slower
than what we're seeing today.
than what we're seeing today.
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And this coincided with a mass extinction
of many marine species.
of many marine species.
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So is that what we're headed for?
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Well, maybe.
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Studies are showing
some species are actually doing quite well
some species are actually doing quite well
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but many are showing a negative response.
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One of the big concerns is
as ocean acidity increases,
as ocean acidity increases,
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the concentration of carbonate
ions in seawater decrease.
ions in seawater decrease.
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Now these ions are basically
the building blocks
the building blocks
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for many marine species
to make their shells,
to make their shells,
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for example crabs or mussels, oysters.
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Another example are corals.
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They also need these carbonate
ions in seawater
ions in seawater
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to make their coral structure
in order to build coral reefs.
in order to build coral reefs.
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As ocean acidity increases
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and the concentration
of carbonate ions decrease,
of carbonate ions decrease,
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these species first find it more difficult
to make their shells.
to make their shells.
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And at even even lower levels,
they can actually begin to dissolve.
they can actually begin to dissolve.
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This here is a pteropod,
it's called a sea butterfly.
it's called a sea butterfly.
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And it's an important food source
in the ocean for many species,
in the ocean for many species,
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from krill to salmon right up to whales.
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The shell of the pteropod
was placed into seawater
was placed into seawater
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at a pH that we're expecting
by the end of this century.
by the end of this century.
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After only 45 days
at this very realistic pH,
at this very realistic pH,
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you can see the shell
has almost completely dissolved.
has almost completely dissolved.
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So ocean acidification could affect
right up through the food chain --
right up through the food chain --
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and right onto our dinner plates.
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I mean who here
likes shellfish? Or salmon?
likes shellfish? Or salmon?
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Or many other fish species
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whose food source
in the ocean could be affected?
in the ocean could be affected?
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These are cold-water corals.
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And did you know we actually have
cold-water corals in Irish waters,
cold-water corals in Irish waters,
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just off our continental shelf?
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And they support rich biodiversity,
including some very important fisheries.
including some very important fisheries.
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It's projected that
by the end of this century,
by the end of this century,
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70 percent of all known cold-water corals
in the entire ocean
in the entire ocean
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will be surrounded by seawater
that is dissolving their coral structure.
that is dissolving their coral structure.
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The last example I have
are these healthy tropical corals.
are these healthy tropical corals.
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They were placed in seawater at a pH
we're expecting by the year 2100.
we're expecting by the year 2100.
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After six months, the coral
has almost completely dissolved.
has almost completely dissolved.
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Now coral reefs support
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25 percent of all marine life
in the entire ocean.
in the entire ocean.
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All marine life.
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So you can see: ocean
acidification is a global threat.
acidification is a global threat.
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I have an eight-month-old baby boy.
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Unless we start now to slow this down,
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I dread to think what our oceans
will look like when he's a grown man.
will look like when he's a grown man.
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We will see acidification.
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We have already put too much
carbon dioxide into the atmosphere.
carbon dioxide into the atmosphere.
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But we can slow this down.
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We can prevent the worst-case scenario.
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The only way of doing that
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is by reducing our
carbon dioxide emissions.
carbon dioxide emissions.
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This is important for both you and I,
for industry, for governments.
for industry, for governments.
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We need to work together,
slow down global warming
slow down global warming
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slow down ocean acidification
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and help to maintain a healthy ocean
and a healthy planet
and a healthy planet
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for our generation
and for generations to come.
and for generations to come.
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(Applause)
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ABOUT THE SPEAKER
Triona McGrath - Chemical oceanographerTriona McGrath researches how the oceans are changing due to human activities.
Why you should listen
Dr. Triona McGrath researches how the oceans are changing due to human activities, particularly in relation to ocean acidification. Specifically, McGrath monitors levels of carbon dioxide in Irish marine waters to determine the accumulation and movement of carbon in the ocean and subsequent increase in ocean acidity. McGrath and her colleagues published the first rates of ocean acidification for Irish offshore waters and the first baseline dataset of carbon parameters in Irish coastal waters. This is crucial in our understanding of the future health of our oceans along with providing information to determine the impacts of ocean acidification on marine ecosystems.
McGrath is a post-doctorate researcher at the National University of Ireland, Galway, funded by the Marine Institute, Ireland. She has been researching ocean climate change since 2008; her latest research project started in February 2017, and for the next four years she will work with colleagues to further develop ocean acidification research in Ireland through the continuation of an ongoing time series in the Rockall Trough and the determination of seasonal and interannual variability of the carbon system in coastal waters. McGrath is a Fulbright Scholar, receiving a Fulbright Postdoctoral Scholarship in 2013 to visit Prof. Andrew Dickson’s laboratory at Scripps Institution of Oceanography, San Diego to further develop analytical skills in ocean carbon chemistry.
McGrath has a Ph.D. in Chemical Oceanography and Bachelor of Marine Science from the National University of Ireland, Galway.
Triona McGrath | Speaker | TED.com