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How pollution is changing the ocean's chemistry | Triona McGrath | TEDxFulbrightDublin

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    Do you ever think about how important
    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
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    including 20 percent of protein
    to feed the entire world population.
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    People used to think
    that the oceans were so vast
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    that they wouldn't be affected
    by human activities.
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    Well today I'm going to tell you
    about a serious reality
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    that is changing our oceans
    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
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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
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    since carbon dioxide
    is one of the greenhouse gases
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    that's causing climate change.
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    But as we keep pumping
    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.
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    When carbon dioxide dissolves in seawater,
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    it undergoes a number
    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.
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    But I'll tell you as more
    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.
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    And this whole process
    is called ocean acidification.
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    And it's happening
    alongside climate change.
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    Scientists have been monitoring
    ocean acidification for over two decades.
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    This figure is an important
    time series in Hawaii,
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    and the top line shows steadily increasing
    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.
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    The line underneath shows the increasing
    concentrations of carbon dioxide
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    that is dissolved
    in the surface of the ocean
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    which you can see is increasing
    at the same rate
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    as carbon dioxide in the atmosphere
    since measurements began.
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    The line on the bottom shows
    then shows the change in chemistry.
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    As more carbon dioxide
    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.
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    Now in Ireland, scientists are also
    monitoring ocean acidification --
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    scientists at the Marine
    Institute and NUI Galway.
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    And we, too, are seeing
    acidification at the same rate
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    as these main ocean time-series
    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
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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.
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    So as you can imagine,
    in the North Atlantic
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    we get hit with some seriously
    stormy conditions --
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    so not for any of you
    who get a little motion sickness,
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    but we are collecting
    some very valuable data.
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    So we lower this instrument
    over the side of the ship,
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    and there are sensors
    that are mounted on the bottom
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    that can tell us information about
    the surrounding water,
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    such as temperature
    or dissolved oxygen.
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    And then we can collect our seawater
    samples in these large bottles.
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    So we start at the bottom,
    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.
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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
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    or back in the laboratory
    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?
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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
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    since pre-industrial times,
    which is directly due to human activities.
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    Unless we can start slowing down
    our carbon dioxide emissions,
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    we're expecting an increase
    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.
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    This rate of acidification
    is 10 times faster
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    than any acidification in our oceans
    for over 55 million years.
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    So our marine life have never,
    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.
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    Now there was a natural acidification
    event millions of years ago,
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    which was much slower
    than what we're seeing today.
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    And this coincided with a mass extinction
    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
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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,
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    the concentration of carbonate
    ions in seawater decrease.
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    Now these ions are basically
    the building blocks
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    for many marine species
    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
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    to make their coral structure
    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,
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    these species first find it more difficult
    to make their shells.
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    And at even even lower levels,
    they can actually begin to dissolve.
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    This here is a pteropod,
    it's called a sea butterfly.
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    And it's an important food source
    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
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    at a pH that we're expecting
    by the end of this century.
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    After only 45 days
    at this very realistic pH,
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    you can see the shell
    has almost completely dissolved.
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    So ocean acidification could affect
    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?
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    Or many other fish species
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    whose food source
    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,
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    just off our continental shelf?
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    And they support rich biodiversity,
    including some very important fisheries.
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    It's projected that
    by the end of this century,
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    70 percent of all known cold-water corals
    in the entire ocean
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    will be surrounded by seawater
    that is dissolving their coral structure.
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    The last example I have
    are these healthy tropical corals.
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    They were placed in seawater at a pH
    we're expecting by the year 2100.
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    After six months, the coral
    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.
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    All marine life.
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    So you can see: ocean
    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.
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    We will see acidification.
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    We have already put too much
    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.
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    This is important for both you and I,
    for industry, for governments.
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    We need to work together,
    slow down ocean acidification
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    and then we can 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
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    for our generation
    and for generations to come.
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    (Applause)
Title:
How pollution is changing the ocean's chemistry | Triona McGrath | TEDxFulbrightDublin
Description:

In this talk, Dr. Triona McGrath explains how our oceans are changing due to increasing levels of carbon dioxide in the atmosphere and how it will impact our marine life. Triona shares her thoughts on ocean acidification and explain why it is the evil twin of climate change.

Dr. Triona McGrath is a Fulbright scholar and post-doctorate research fellow, currently working with the National University of Ireland, Galway and the Marine Institute, Ireland. Her primary area of research is chemical oceanography where she is investigating ocean acidification in Irish marine waters. In 2014, Triona was a Fulbright-Marine Institute Scholar at the Scripps Institute of Oceanography in San Diego.

This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at http://ted.com/tedx

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Video Language:
English
Team:
closed TED
Project:
TEDxTalks
Duration:
09:45

English subtitles

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