Ocean Acidification: The Evil Twin of Climate Change by Triona McGrath (Transcript)

Here is the full transcript of Chemical oceanographer Triona McGrath’s TEDx Talk on Ocean Acidification: The Evil Twin of Climate Change at TEDxFulbrightDublin conference. For more info on the speaker, read the bio here.


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Triona McGrath – Chemical oceanographer

Do you ever think about how important the oceans are in our daily lives?

The oceans cover two-thirds of our planet. They provide half the oxygen we breathe. They moderate our climate. And they provide jobs and medicine and food, including 20% of protein to feed the entire world population.

People used to think that the oceans were so vast that they wouldn’t be affected by human activities. Well today I’m going to tell you about a serious reality that is changing our oceans called ocean acidification, or the evil twin of climate change.

Did you know that the oceans have absorbed 25% of all of the carbon dioxide that we have emitted to the atmosphere? Now this is just another great service provided by the oceans since carbon dioxide is one of the greenhouse gases that’s causing climate change.

But as we keep pumping more and more and more carbon dioxide into the atmosphere, more is dissolving into the oceans. And this is what’s changing our ocean chemistry.

When carbon dioxide dissolves in seawater, it undergoes a number of chemical reactions. Now lucky for you, I don’t have time to get into the details of the chemistry for today. But I’ll tell you as more carbon dioxide enters the ocean, the seawater pH goes down. And this basically means that there is an increase in ocean acidity. And this whole process is called ocean acidification. And it’s happening alongside climate change.

Scientists have been monitoring ocean acidification for over two decades. This figure is an important time series in Hawaii, and the top line shows steadily increasing concentrations of carbon dioxide, or CO2 gas, in the atmosphere. And this is directly as a result of human activities.

The line underneath shows the increasing concentrations of carbon dioxide that is dissolved in the surface of the ocean which you can see is increasing at the same rate as carbon dioxide in the atmosphere since measurements began.

The line on the bottom then shows the change in chemistry. As more carbon dioxide has entered the ocean, the seawater pH has gone down, which basically means there has been an increase in ocean acidity.

Now in Ireland, scientists are also monitoring ocean acidification — scientists at the Marine Institute and NUI Galway. And we, too, are seeing acidification at the same rate as these main ocean time-series sites around the world. So it’s happening right at our doorstep.

Now I’d like to give you an example of just how we collect our data to monitor a changing ocean.

Well, firstly we collect a lot of our samples in the middle of winter. So as you can imagine, in the North Atlantic we get hit with some seriously stormy conditions — so not for any of you who get a little motion sickness, but we are collecting some very valuable data.

So we lower this instrument over the side of the ship, and there are sensors that are mounted on the bottom that can tell us information about the surrounding water, such as temperature or dissolved oxygen.

And then we can collect our seawater samples in these large bottles. So we start at the bottom, which can be over 4 kilometers deep just off our continental shelf, and we take samples at regular intervals right up to the surface.

We take the seawater back on the deck, and then we can either analyze them on the ship or back in the laboratory for the different chemicals parameters.

But why should we care? How is ocean acidification going to affect all of us? Well, here are the worrying facts.

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