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Ocean Acidification is a global-scale change in the basic chemistry of oceans that is under
way now, as a direct result of the increased carbon dioxide in the atmosphere.
We are just beginning to understand the impacts of Ocean Acidification on life in the ocean.
The moniker “osteoporosis of the sea,” gives you a hint about some of its impacts.
The basic chemistry of Ocean Acidification is well understood -- - not controversial.
Here are three key concepts:
First, the chemistry of the oceans is dependent upon the chemistry of the atmosphere.
More carbon dioxide (carbon dioxide) in the atmosphere means more carbon dioxide in the ocean.
Second, as carbon dioxide from the air is dissolved in the ocean, it makes the ocean more acidic.
And third, the resulting changes in the chemistry of the oceans disrupt the ability of plants
and animals in the sea to make shells and skeletons of calcium carbonate.
And those chemical changes also dissolve shells already formed.
Who in the in oceans is affected?
Any plant or animal with a shell or skeleton made of calcium carbonate.
The hard parts of many familiar animals such as oysters,
clams, corals, lobster, crabs - such as the ones on this table
are made of calcium carbonate.
Many microscopic plants and animals at the base of the food chain
also have calcium carbonate shells or skeletons.
Some of these microscopic plants and animals
are so abundant that when they die, their shells accumulate on the seafloor in massive deposits.
The famed white cliffs of Dover are a familiar example of calcium carbonate - or chalk
- deposits - the skeletons of microscopic organisms.
Acidic ocean water is corrosive to all of these calcium carbonate shells and skeletons,
but let me focus on two quick examples.
First, Corals, which provide the fundamental structure for the world’s treasured coral
reef ecosystems, make their skeletons with calcium carbonate.
If ocean water is more acidic, it is harder for corals to make their hard parts.
If the ocean becomes too acidic, coral reefs may well disappear.
The second example is Pteropods - also called 'sea butterflies'- are small, shelled animals
about the size of a lentil bean. They occur in the millions off the coast of my home state
of Oregon, but also throughout the world's oceans. They are a key or the primary source
of food for juvenile salmon and many other fish around the world. Pteropods are particularly
susceptible to increasingly acidic ocean water, as you'll see in a moment.
I mention them in part because they illustrate the broader consequences of a disruption to
one part of an ocean ecosystem reverberating throughout the rest of the system, potentially
affecting jobs, food security, tourism and more. Because pteropods are a main source
of food for juvenile salmon, mackerel, *** and herring, their demise will likely affect
all of their predators, some in a major fashion.
The severity of the impact of ocean acidification is likely to depend in part on the interaction
of acidification with other environmental stresses, such as rising ocean temperatures,
over-fishing and pollution from the land.
Early evidence suggests that some species are better equipped to thrive in increased
acidity, but the adaptability of most organisms to increasing acidity is unknown.
While our understanding of ocean acidification’s impacts are still unfolding, the basic science
of how the ocean is acidifying and the effect of increased acidity on some marine organisms
is well-known. I would now like to demonstrate two of the basic concepts I mentioned earlier.
The ocean does a great service by absorbing tremendous amounts of carbon dioxide from the atmosphere.
In fact, the oceans have absorbed about one-third of the carbon dioxide that humans have added to the atmosphere
over the last 2 centuries, greatly reducing the impact of this heat-trapping pollutant on the climate.
But the carbon dioxide absorbed by the ocean changes the chemistry of the seawater,
making it more acidic and corrosive.
When carbon dioxide dissolves in water, it forms carbonic acid, making the water more acidic.
I would now like to demonstrate two of the basic concepts I mentioned earlier.
To illustrate how this occurs, I have a vessel of water
that I will pour into this container
and I have a common laboratory blue dye
that changes color depending on the acidity of the solution which it is
so let me put a few squirts of this blue dye into this tap water
make it a nice blue color here
one more squirt for good measure
and I have some frozen carbon dioxide
otherwise known as dry ice
okay so this is ordinary water
its blue color illustrating that it is neutral acidity
as I drop in dry ice or carbon dioxide
into the water the carbon dioxide changes to carbonic acid
and that in turn changes the acidity of the water
and so you can see graphically
the blue changing to yellow illustrates that the water has
become more acidic
now I emphasize that this is tap water that we've used
but the same principle holds true for the oceans
if we make them, when they absorb more carbon dioxide
that simply makes them more acidic
but the second key concept that I want to emphasize
is that the impact increasing acidity on shells made of calcium carbonate
is a function of the level of acidity in the water
so I have three glasses
into the first one I will pour water
into the second wind I will pour half water and half vinegar
an into the third one I will pour vinegar
so we have three beakers
this is more acidic
because vinegar as you know is a weak acid
and in this is more acidic so we have a gradient in acidity
I will take sticks of chalk, calcium carbonate
when I was growing up the chalk that we used in classrooms was pretty much
pure calcium carbonate
most chalk today is not completely calcium carbonate
there are other things in it to make it less breakable and less dusty
so if you try this at home
you need to get the stuff that's mostly made of calcium carbonate
we put it into water of neutral acidity and the chalk just sits there
just like most shells in sea water are not affected by the water around them
if however I put the chalk sticks into the beaker that has
half water and half vinegar you can see bubbles beginning to form
as the chalk begins to dissolve in the water
those bubbles are carbon dioxide that is being formed
as the calcium carbonate is dissolving
and if I put the chalk into the vessel that is pure vinegar
that dissolving of the calcium carbonate happens even faster
the ocean will never be as acidic as the vinegar we've used here
I'm using vinegar just as a dramatization of the effects of ocean acidity
because I only have a few minutes to demonstrate these basic concepts
so increasing acidity makes the shells disslove faster
and the water becomes more acidic
as it absorbs carbon dioxide from the atmosphere
but let's move from a chemical demonstration to a biological one
to show you the effects of the projected increase in acidity in oceans worldwide
I've brought a short
one minute video clip
before I start the clip let me describe what you'll see
the first ten seconds will show a living swimming petropod or sea butterfly
which I mentioned earlier
about the size of a lentil bean, pteropods play a key role in ocean ecosystems
in part as I mentioned because they provide food for juvenile salmon
mackrel, pollack, and herring
following the healthy pteropod in today's ocean
you'll see if that happens to a pteropod in sea water
by the end of this century if nothing
is done to reduce the carbon emissions
let's start the video
here we see the normal healthy pteropod swimming the the ocean
this is what it should look like
and now we will see a pteropod shell
that is in ocean water that's what we expect to be by the end of this century
and as you can see
with more days in this
increasingly acidic ocean
the shell is completely dissolved
and animal would not be healthy
this last clip is an animation illustrating from the year
seventeen sixty five to twenty one hundred
the effect that increasing ocean acidity
on the availability of calcium carbonate mineral
that pteropods, corals and other such organisms
need to create their shells and skeletons
the projections assume a business as usual emissions scenario
a change in the color of the animation for purple to pollute a yellow to red
indicates increasing ocean acidity and decreasing availability
of a form of calcium carbonate needed
for the formation of many shells and skeletons
ocean acidity has increased by thirty percent
since the beginning of the industrial revolution
just over two hundred years ago
this increase
it's one hundred times faster
that any change in acidity experienced by marine organisms
for at least twenty million years
by the middle of the century
it is expected that coral calcification rates
will decline by a third
for an erosion of corals will outpace new growth
making many coral reefs unsustainable
and by the year twenty one hundred vast areas of the ocean
ultimately shown here in red
will have preached a level of a acidification
where pteropods, corals, and other important marine species
will likely be severely compromised
by the increasingly corrosive nature
of the sea water there
Our understanding of the impacts of ocean acidification is relatively new.
Roughly two thirds of the published research has come to light since 2004.
Thanks to Congress’ action in passing the Federal Ocean Acidification Research and Monitoring Act,
more attention will be given to this subject, particularly by scientists at NOAA
and our partners at the National Science Foundation and in academia.
Nonetheless, the fundamental scientific understanding of the basic chemistry of ocean acidification
is sound.
More carbon dioxide emitted into the atmosphere will lead to more carbon dioxide being absorbed into our oceans,
and this in turn will result in increasing ocean acidity.
Recent evidence suggests that the ocean’s very capacity to absorb carbon dioxide from the atmosphere
may be slowing down, degraded by ocean acidification.
These mechanisms can only be addressed by decreasing
the amount of carbon dioxide that enters the atmosphere.
The dramatic impacts that ocean acidification can and will have on ocean ecosystems are clear.
And we can see, looking back, the dissolution of chalk in the most acidic water here
how problematic that might be for many plants and animals that we depend upon