How the Ocean Stores Carbon Dioxide

The planet is in dire straits. Temperatures are rising. The ocean is getting sour. People are suffering.

Companies make promises. Governments sign pledges. You are recycling your plastics. Even your neighbor is using that green dish soap now. With millions of trees getting planted, surely, we’re making a dent, right?

To find out, let’s put ourselves into the shoes of a carbon dioxide molecule, and see where we end up. Trees? Soil? Whale poop? Wait, what? Let’s take a deep breath and dive in.

What to Expect in this Article

  • What is the Climate?
  • What Determines Earth’s Climate?
  • The Sun and the Climate
  • The Wobbling Earth and Moon
  • How Carbon Dioxide Enters the Atmosphere
  • The Ocean as a Buffer
  • The Whale Poo Express
  • Whale-Sized Issues
  • Solutions

What is the Climate?

We’ll focus on the ocean in this article, but to be able to understand just how awesome the ocean is, we need some ground covered.

First, as everyone from my neighbor to that former orange US president can’t keep it straight, let’s talk about the weather… um, climate. Weather describes short-term changes in the atmosphere, the behavior of the atmosphere, and the effects on human activity. Climate is the condition of the atmosphere at a certain place over a longer period as an average, typically over 30 years.

The world is divided into climate regions based on temperatures and precipitation, from tropical to polar and arid, from temperate to continental.

The important thing to keep in mind is that it’s about long-term averages whenever we discuss the climate, so your current weather doesn’t have much influence at all.

What Determines Earth’s Climate?

Very simply put, energy from the sun reaches Earth’s atmosphere. Some of that energy is reflected back immediately by the atmosphere’s gases, some by the planet itself. And the rest is absorbed by the atmosphere and planet. Everything on Earth constantly emits long-wave radiation. Without our atmosphere, we’d live at -19 degrees Celsius, but thanks to the greenhouse effect, the average temperature on Earth is much more comfortable.

The most important greenhouse gases are water vapor and carbon dioxide. However, the most abundant gases (nitrogen and oxygen) are very shitty greenhouse gases and have little effect on Earth’s temperature.

Clouds also trap greenhouse gases underneath themselves, making it warmer underneath the cloud. But, as clouds are usually brighter than the surfaces they shield, this is somewhat offset by their albedo/reflectivity. On average, clouds thus have a cooling effect on the climate. But, especially at night, they can make it feel warmer locally, as the warm air stays trapped longer.

The Sun and the Climate

The sun is pretty clam old and emits a boatload of energy. The surface temperature of the sun is a very uncomfortable 5,500 degrees Celsius. Every square meter of the sun’s surface emits about 60 Watts of energy, all due to fusing hydrogen atoms into helium atoms. The difference in mass between the four hydrogen atoms and the one helium atom is less than a percent, but this difference translates into a crabton of energy.

People like to blame variations of the sun for the changes in the climate, but that’s just nonsense. Yes, fluxes in magnetic properties on the sun’s surface cause faculae with darker centers that can be seen as dark spots. These dark spots are less dense and cooler. The magnetic field of the sun flips during each solar cycle. Over the course of about 11 years, there are times with fewer and times with more sunspots. But the effect is minimal. Even a solar maximum, so a time with the maximum amount of sunspots, changes the output of energy by only 0.1%.

The Wobbling Earth and Moon

There are other factors influencing the climate, such as the earth and the moon essentially wobbling around their axes. There are different factors such as the shape of Earth’s orbit (eccentricity), which has a 41,000-year cycle, the rotational tilt of Earth (obliquity) with a 100,000-year cycle, and a change in the orientation of that rotational axis (precession) over a 25,000-year cycle. As you can tell, these cycles are ducking long, so they don’t explain what’s been happening since the Industrial Revolution, no matter how much people like to blame natural variation for the climate crisis.

And one of these is even mitigating the effects of climate change currently: moon wobbles (nutation). The moon follows a cycle of about 19 years. During half of that time—and currently—the moon lowers the tides. During the other half—and starting sometime in the 2030s—the moon increases tides. So, yet another factor that will make life less comfortable after 2030. What a great time to be alive… Well, I certainly hope I’ll see the metaphorical tide turn way before this change happens, and sea levels rise even faster.

In addition to these, there are many other factors such as volcanic eruptions, meteorites, plate tectonics, earthquakes and such—and, of course, adding endless amounts of greenhouse gases into the atmosphere. And before anyone suggests geoengineering: no, just no. We’ll talk about why that’s such a crabby idea in a future episode.

How Carbon Dioxide Enters the Atmosphere

There are countless ways for carbon dioxide to get into the atmosphere from burning dinosaur slurry aka fossil fuels to your own breath. Every time you breathe out, you add carbon dioxide to the atmosphere.

Wait, don’t hold your breath to save the planet. You’ll die, and then you’ll release the carbon dioxide anyway. Not worth it. Breathing? Okay, let’s continue.

The little CO2 molecule leaves your mouth and joins the millions upon millions of its fellows in the atmosphere. On average, it’ll stay there for 300 to a 1,000 years, so longer than you’ll even stay breathing.

But where does it go then?

Remember, carbon dioxide is carbon and oxygen. We don’t mind the oxygen hanging around. Every plant, every animal, ever damn mushroom needs oxygen. Okay, yes, there’s this weird parasitic animal that infect salmon that can survive without, but let’s not make this complicated. So, what we really care about is where the carbon goes.

The Ocean as a Buffer

The bottom of the ocean is the largest pool of organic carbon on the entire ducking planet. Duck trees, seriously. If we leave the bottom of the ocean alone, the carbon stored there can stay there for millions of years.

The ocean is the most effective carbon sink we have. Let’s put that into perspective: The entire atmosphere holds about 750 petagrams or gigatons of Carbon. The soil stores about twice as much as the atmosphere (1,580 GtC) but that’s still nothing to how much is stored in the deep sea. Duck, just the surface ocean stores more than the atmosphere (1,020 GtC). The deep sea stores about 38,000 gigatons. Yes, 38,000 gigatons. So, we better leave that shit alone, right?

Carbon Cycle by Kevin Saff

But how does the carbon get to the deep sea, and where is all that carbon stored? It’s time to talk about poo.

The Whale Poo Express

There are various ways for carbon to get into the ocean. At the surface, some is absorbed from the air. Many of the tiny organisms in the surface layer are photosynthetic, so they take energy from the sun and carbon dioxide to make oxygen and grow. That grows stores carbon in the little greenies.

These little greenies are then eaten by a little less tiny organisms, so the carbon moves up the foodchain.

And that leads us to the coolest part of this cycle: the poo express. Of course, only some of the food becomes body weight. We all know what happens to the rest of the food. When, let’s say, a whale shits, quite a bit of that shit is organic matter, so carbon. Shit is very well suited to falling fast. From an ergonomic shape to the density, everything about the whale poo is created for fast sinking. And that moves a shitton of the carbon down to the bottom of the ocean. Sure, some of it is reabsorbed or eaten higher up but a lot of it goes down… down… down.

And remember: it’s not just whales that poop. There’s a lot of shit in the ocean.

Another thing that sinks carbon dioxide to the bottom of the ocean is the actual dying organisms. When the smaller stuff dies, the corpse get eaten and absorbed, but some animals sink to the bottom of the ocean without getting munched up near the surface. In the case of whales, there’s even a word for it: whale fall.

And before anyone suggests we sink all the whales: I’m pretty sure that the poo express sequesters more carbon than whale falls over a whale’s lifetime. So, don’t even think about it.

Whale-Sized Issues

There are a few really big issues with how much buffering the ocean has to do because humans like to burn fossil fuels and stir up sediment to exploit the ocean.

Stirring Up Sediment

Last week, in our review on fishing methods, I already mentioned that bottom trawling and dredging are serious issues here. They stir up the sediment at the bottom of the ocean and release some of that stored carbon. Between 2016 and 2019, only 1.3% of the ocean were dredged or trawled, but that already releases more carbon dioxide than the entire airline industry. And various nations are alredy talking about deep-sea mining for polymetalic nodules to get stuff like manganese from the deep sea. I don’t even want to think about how much sediment that’s going to stir up—not even mentioning the habitat they’ll destroy. Deep-sea mining is definitely something we should stop before it’s even started.

Fishing and Whaling

Another whale-sized issue is removing organisms from the ocean. The average whale sequesters 33 tons of carbon dioxide over its lifetime, first via the poo express, and later by sinking to the bottom of the ocean either as a corpse or as the poo of other animals. Compare that to a tree with a measly 21 kilograms of carbon per year. Yes, yes, I’m comparing the lifetime of a whale to the carbon a tree sequesters in a year. Let’s change that. A quick search reveals that the average whale has a lifespan of 40 to 70 years. Let’s be generous and use the 70 years for our math. 33 tons of carbon dioxide divided by 70 years, still means 0.47 tons or 470 kilograms of carbon dioxide sequestered by a whale in a year. And yes, yes, I know that includes the dead whale at the end of the lifetime, but I can’t math everything.

This means whaling might just be one of the shittiest practices for the climate. But, keep in mind that we take out boatload after boatload of fish, shrimp, and other organisms, so while one whale might have a larger impact than one fish, taking millions of fish out of the ocean has similar issues. Overfishing is bad for the climate, no matter how you put it. Luckily for us, research has already shown that recovering fish stocks quickly take up sequestering carbon again, so this is not irreversible if we can manage to protect the ocean.

A Sour Ocean

Chemistry isn’t my strong suit, so I’ll keep this brief. How acidic something is is determined by the number of hydrogen ions in a solution. When carbon dioxide enters the ocean, it reacts with the water, and forms first carbonic acid and then carbonate ions and hydrogen ions. As hydrogen ions are what makes the ocean sour, this is a pretty big deal.

The more the ocean has to buffer, the more acific it gets. And organisms can’t keep up. We’ve all heard about coral bleeching. But corals are not the only victims of ocean acidification and rising surface temperatures.

Especially organisms with calcified shells struggle a lot. From mussels to crabs, anything with a calcium carbonate shell has issue with the shell quality when the ocean gets more acidic. There is something called the CCD, the Calcium Compensation Depth, below which organsims with calcified shells can’t live because their shells get dissolved. And anthropogenic CO2 emissions are changing where that depth is.

But even organisms without shells struggle with the changing conditions. Imagine you are a single-celled organism and your metabolism is maintained by the difference between your inside and the outside ocean. When the balances are off, you need to work a lot harder to actively keep your insides on your insides.

Rising ocean temperatures and ocean acidification are stressful for most—if not all—organisms in the ocean from single-celled little shit to whales, from plants and algae to crabs.

And even with all the work the ocean is doing, it can’t buffer what we blast into the atmosphere fast enough.


As always, there are solutions here. Protecting a third of the ocean is really the bare minimum here—and that’s the goal governments and such aim for at the moment. I know it’s hard to believe, but research has shown that we can protect about 70% before we even lower food output, so let’s go all in here! Maybe, at the very least, don’t aim for the minimum…

Marine protected areas would allow fish stocks to recover—and thus store more of our overdose on carbon dioxide. It would also provide a sancturay to animals like whales and dolphins.

But a lot of the large whales are migratory or, at least, roaming, so local protection doesn’t help them enough. We need to stop whaling altogether. Norway, I’m talking to you, here. Stop that ducking shit!

There is a lot we can do. It’s time to demand change. We can still do this together!

Want to keep learning? Read this article on crabs to learn a crabton about crabs.