It's a pleasant morning in July, and you're excited to head to the beach for your summer vacation. The sun shines brightly overhead, and you graciously feel its warmth on your skin. When you arrive, a cool ocean breeze blows gently across your face, and the sound of seagulls fills the sky.
You can't wait to feel the cool water on your feet, so you run toward the shore. The sand feels soft between your toes. As the first wave washes over your feet, you’re reminded of your childhood summers spent with your parents. You think about the fun times you had, laughing and playing in the water. It feels like time has stopped, and everything is just perfect.
Standing there, feeling happy and relaxed, you think to yourself that this is the best day of your life. The water is refreshing, the sun is shining, and you're with the people you love.
But beneath this idyllic scene, something bad is happening in the water at the exact moment. The same ocean that brings you so much joy is also slowly poisoning everything in it. The ocean's beauty is hiding a dangerous secret that will soon ruin everyone's livelihood.
Oceans cover two-thirds of the Earth's surface and are home to the majority of life forms on our planet. In fact, it is even believed that life on Earth began in the oceans. Such prominence holds our ocean waters. Not only do they provide us with food in the form of fish, and essential minerals in the form of table salt, but they are doing one more important thing.
They are breathing !!
The oceans are at a constant equilibrium with the CO₂ in the atmosphere. That means if there is excess CO₂ in the atmosphere, they get dissolved in the ocean and when there’s excess CO₂ in the water, it gets emitted back. Hold on to this, as it becomes important later.
You might wonder what the ocean does with all this dissolved CO₂.
That's where our invisible, minute warriors, phytoplankton, come into play. These microscopic, single-celled organisms, measuring just 0.2 micrometres, live on the top layers of the ocean. They use sunlight and CO₂ to produce oxygen. If this sounds similar to trees, you’re absolutely right.
Did you know ?
The oceans are responsible for producing about 50% of the world's fresh oxygen.
Phytoplankton are the foundational organisms of the ocean's food web, playing a critical role not only as a food source for zooplankton but also in providing the dissolved oxygen for the larger marine animals to breathe. The Food chain of the ocean would typically look like this:
Phytoplankton → zooplankton → fish → larger fish → sharks,
dolphins, and whales.
Here's an image to illustrate this process.
In this way, our oceans act as one of our greatest buffers against climate change. Humans emit around 35 billion tons of CO₂ a year. Half of it remains in the atmosphere (increasing the PPM of CO2), while the rest is absorbed by the ocean. To put this in perspective, the Amazon rainforest absorbs around 2.3 billion tons of CO₂ annually, while the oceans absorb nearly 10 billion tons - almost five times more.
But there's even more. Unlike trees, which can release CO₂ back into the atmosphere when they decay or while they are cut down and burnt, the CO₂ absorbed by the oceans mostly remains within.
Phytoplankton that are not consumed by other marine organisms eventually sink to the seafloor, trapping the CO₂ within them and locking it away in the depths of the ocean. This process known as the Ocean’s Biological pump is significant because much of the oil found today on the ocean bed originates from these phytoplankton.
But lately, there's a huge problem with our oceans. They are becoming more acidic!!
You might wonder how this can be? After all, the last time you dipped your feet in seawater, it didn't burn your feet.
Scientifically speaking, when the concentration of H+ ions in a substance increases, it becomes more acidic. The excessive carbon dioxide we emit into the atmosphere is directly linked to the formation of carbonic acid in the ocean, leading to gradual increase in acidity. The following image describes this in a simpler way:
So, the oceans absorb our CO₂, produce oxygen, and more CO₂ means more food for phytoplankton, which in turn provides more food for fish and other marine life. It seems like a win-win situation. Where’s the problem? - well there's just too much CO₂.
First, phytoplankton are very sensitive to changes in their environment. They require the right balance of CO₂ and temperature to thrive. The ocean maintains a constant equilibrium with the atmosphere. This means that as CO₂ levels in the atmosphere rise, more of it dissolves in ocean water, disrupting this delicate balance. Combined with increasing water temperatures and CO₂ levels, the productivity of useful phytoplankton is declining. (There are certain invasive species of phytoplankton that cause algal blooms that thrive under the forthcoming situations, but they cause more harm than good.)
Second, coral reefs are experiencing severe bleaching due to the increased ocean acidification. Even if we manage to limit global warming to the levels set by the Paris agreement, sadly 90% of corals are expected to die. If global temperatures rise by 2°C, that figure jumps to 99%. If you are planning a trip to Australia to scuba dive and see the Great Barrier Reefs, you might want to do it soon.
Third, increasing acidity of the oceans makes it harder for marine organisms like mollusks - such as clams, oysters, and snails - to build their shells. As the ocean becomes more acidic, these organisms struggle to extract the calcium and carbonate ions they need, resulting in weaker shells and, ultimately, threatening their survival.
The Bigger Picture
You might be thinking,
“Well, don't worry - Carbon Capture technology will solve all our problems.
We can just remove all the excess CO₂ !”
Unfortunately, it’s not that simple. If you remember, the ocean and the atmosphere are in a constant equilibrium. This means that if we start removing CO₂ from the air, CO₂ that has been absorbed by the oceans for so long, will start to be released back into the atmosphere. Thus the ppm levels of CO₂ in the air would not decrease as much as we would like.
As mentioned in a previous article in Sustainability Advocates, one ppm equates to 7.8 billion tons of CO₂. However, to remove one ppm of CO₂ requires the removal of 12-14 billion tons of CO₂, considering this back-emissions effect from the oceans. Dear reader, if you’re a leader in politics or business, this is your call to action. If you really want to help the planet and decrease the ppm of CO₂ in the atmosphere, remind yourself that offsetting 10 tons of emissions may require removing 15 tons due to the back-emission effect.
Does that mean we have to give up on carbon capture?
Absolutely not. But it’s important to understand that this technology is not a silver bullet that will solve all our problems. We must be mindful of both our actions as well as inactions. The car ride you just took for grocery shopping, the optional flight, and even the simple act of not sorting your trash. All these in minute ways adds to the problem.
We are already living on borrowed time and like every loan, our CO₂ budget is no different; the bill always comes due.
In summary, our oceans are facing a crisis that threatens both marine life and human livelihoods. The increase in ocean acidification, driven by excessive CO₂ emissions, is disrupting ecosystems, damaging coral reefs, and making it difficult for marine organisms to survive.
With your help, we can still rewrite this story.
But until next time....
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Send your feedback and any further questions regarding the topic via email to sdgadvocates@station.dk
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References:
How is acidity naturally controlled in the Oceans – The Ocean Acidification Problem. (n.d.). Retrieved August 10, 2024, from https://sites.gatech.edu/oalearn/ocean-acidification/acidity-of-the-oceans/
How the ocean absorbs carbon dioxide « World Ocean Review. (n.d.). Retrieved August 10, 2024, from https://worldoceanreview.com/en/wor-8/the-role-of-the-ocean-in-the-global-carbon-cyclee/how-the-ocean-absorbs-carbon-dioxide/
Ocean Acidification. (n.d.-a). Retrieved August 10, 2024, from https://www.pmel.noaa.gov/CO2/story/Ocean+Acidification
Ocean acidification: Average pH of the world’s oceans. (n.d.-b). Statista. Retrieved August 10, 2024, from https://www.statista.com/statistics/1338869/average-global-ocean-ph/
Additional Reading:
Why the Amazon rainforest doesn’t really produce 20% of the world’s oxygen. (n.d.). Retrieved August 10, 2024, from https://www.nationalgeographic.com/environment/article/why-amazon-doesnt-produce-20-percent-worlds-oxygen
