Ocean acidification: the main driver of our climate

By Hendrik de Vries,
on 27 September 2022

The sea often plays a beautiful role in life: it provides relaxation with its rushing waves, lets us play and challenges us when we surf and sail. Therefore, many of us (at least on Europe’s side of the planet) associate the sea with a sense of freedom and luxury.

But did you know that the ocean is also essential for our life on Earth, even if you don’t eat fish or shellfish? About half of the oxygen we breathe comes from the ocean. And that very same ocean ensures that we don’t get too hot – in other words: it regulates the temperature. How? By absorbing CO2 – it actually helps us get rid of a greenhouse gas! The ocean isn’t just for luxury or food; it plays a key role – perhaps even the role of the hero – in keeping our planet habitable.

Add to that the sheer scale of the ocean: this blue hero covers more than 70% of the earth. Now it may be clearer why we should not underestimate the role of the ocean – and, more importantly, why we don’t want to disrupt it. But what does its role actually entail?


Capturing CO2: the carbon cycle

The ocean is indispensable for keeping the carbon cycle going, ensuring CO2 ends up in the right places and is used for the right purposes. For example, photosynthesis by algae, plankton and coral provides oxygen and food for other living organisms. And if there is more CO2 left after photosynthesis, the ocean can absorb it deep in the cold water layers for a very long time. In this way, the ocean keeps CO2 out of the air and prevents rising global temperatures.

The ocean has therefore always been the most important player in climate control, according to Marine Geology Professor Gert-Jan Reichart in our podcast On a date with the planet (Op date met de planeet, in Dutch). That is, until humanity left its mark. We have put so much CO2 into the atmosphere that it’s having an impact on what happens in the ocean. The role of our blue hero is slowly changing, and our planet is no longer as habitable as we might think.


Even a hero has its limits

Of all the CO2 that humanity has emitted in the last 120 years, the ocean has absorbed 30% so far, says Gert-Jan Reichart. This proves two things: first, that the ocean is by far the most important ‘player’ on the planet to keep it habitable; and second, that the ocean has to process more and more CO2 to achieve that goal.

It’s therefore important that the ocean continues to work the way it has done up until now. But there are consequences to the increasing amount of CO2 ending up in the water. When CO2 and water react chemically, the result makes the water more acidic. This changes life in the ocean, because acidic water dissolves lime. And lime is vital for many animals that live underwater – coral, shellfish and other organisms use it as a building material. Ocean acidification thus makes these organisms weaker, and they are becoming less common (article in Dutch).

This, in turn, has consequences for humanity, because 14% of the world’s population depends on food sources from the ocean. What’s more, the ocean is becoming saturated with CO2: the more CO2 the ocean absorbs, the more it changes chemically, and the less CO2 it can still absorb. Furthermore, since cold water can absorb CO2 more easily, absorption becomes poorer with the rising temperatures caused by climate change.

Ocean acidification is therefore putting increasing pressure on both our food supply and the blue hero itself, which is crucial for keeping the Earth’s temperature livable.


What can you do?

It’s important we don’t let the ocean acidify further, but how?

To put it bluntly, preventing ocean acidification mainly involves emitting as little CO2 as possible. That’s where the standard measures come in: don’t fly, don’t eat meat, don’t buy new products, insulate your house. You might think we know this now, but the story of our ocean hero confirms once again how important it is to minimize our carbon emissions.

More broadly, there are a number of initiatives that ensure the protection of the ocean:

As frustrating as it is that there are no short-term solutions, this problem shows how beautifully our planet works. All living things on earth are impressively connected, and everything works together. This page of the World Wildlife Fund website features a clip from the documentary Our Planet, in which you can see how this concept applies to life in and around the ocean.

Urgency encourages action, but so does inspiration. Are you discouraged by all the numbers and the feeling that what you can contribute is only a drop in the ocean? Then think of that mighty blue hero that already knows exactly what to do. Try to give the ocean a helping hand; you will be working with a powerful partner.

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