Acid Test: The Global Challenge of Ocean AcidificationAcid Test: The Global Challenge of Ocean Acidification
Watch on YouTube
Ocean acidification: Connecting science, industry, policy and publicOcean acidification: Connecting science, industry, policy and public
Watch on YouTube
About this video
Not just another pretty demonstration.
Dr Andrea Sella of University College London demonstrates how one of his favourite molecules, carbon dioxide, reacts with water.
It's not a complicated experiment: when more and more CO2 dissolves the indicator in the flask changes colour as the water becomes more acidic.
Whilst this make our agua con gas taste great, Sella goes on to explain why the process could also pose an immense threat to ocean biodiversity.
As rising levels of CO2 dissolve in our seas many species – especially those in coral ecosystems – are unable to adapt to increasingly acidic waters.
You can find out more about what has become known as "the other carbon problem" in the footnotes below the video or the additional resources to the right. There's also a really useful video on universal indicator if you're wondering how and why the solution changes colour as it becomes more acidic.
- Professor Andrea Sella
- London, UK
- Filmed in:
- The Theatre
That's the happy sound of one of my favourite molecules, carbon dioxide, being released from captivity inside a bottle of sparkling water.
Now, the reason why sparkling water tastes so fantastic is because the carbon dioxide actually dissolves, giving a slightly acidic carbonic acid.
But what this carbon dioxide look like? Well, I have a little bit of it here. And we've cooled it down so that it's a solid. And it's a very interesting one, because it goes from the solid to the gas without passing through the liquid. So it actually sublimes.
On my left here, I have a big tube of water which has a little bit of indicator in it. Watch what happens when I drop a bit of carbon dioxide into the water.
Of course, the carbon dioxide starts to sublime immediately. And it forms loads and loads of bubbles. But as those bubbles rise through the liquid, a little bit of the carbon dioxide actually dissolves and gradually the pH of the solution begins to change. And so the indicator changes colour. And you can see its now gone from purple to blue. And slowly it's changing from blue to green. And eventually, it will become yellow.
What this is telling us is that the water is becoming more acidic. Now, you might think that this is just another pretty demonstration. It's not. It's actually really serious.
As we put more and more carbon dioxide into the atmosphere, one of the things that is happening is that the CO2 is dissolving in the oceans. And as that happens, the oceans are becoming more and more acidic. And that really spells disaster for all kinds of life forms that can only live in a very narrow range of pH. And so while we have here a beautiful demonstration, in reality it's an alarm signal for what we're doing to our world.