CARBON CYCLE IN THE OCEAN

Let’s take a fun trip with carbon dioxide (CO2) as it travels through the ocean! On this adventure, CO2 will meet some tiny ocean friends like phytoplankton and zooplankton, and we’ll see how it moves around to help keep our planet healthy. Ready? Let’s dive in! Our journey starts when CO2 from the air gets absorbed by the ocean. In fact, about one fourth (25%) of all human-made CO2 ends up in the ocean!
There, we meet phytoplankton—tiny, plant-like creatures that live in the sunny upper part of the ocean, called the surface layer. Just like trees on land, phytoplankton use sunlight to photosynthesize, which means they take in CO2 and turn it into food. This helps them grow and release oxygen, which is super important for us to breathe. In fact, phytoplankton produce about half of the oxygen we breathe. That means every second breath you take is thanks to these tiny ocean plants!

Zooplankton – The Carbon Movers

But phytoplankton don’t stay alone for long. Tiny creatures called zooplankton come along and eat them, and when they do, the carbon inside the phytoplankton gets passed along to the zooplankton. Zooplankton are like tiny ocean animals that carry carbon on its next big adventure. Zooplankton then get eaten by small fish, and those fish might get eaten by even bigger animals like whales. So, as each creature eats another, the carbon gets passed along the food chain—from one animal to another. It’s like a relay race, where carbon keeps moving along through the ocean!

Down, Down, Down – The Big Sink

Eventually, some of the phytoplankton and zooplankton die. When they do, their bodies start to sink to the bottom of the ocean. This is called the biological pump—it’s like a giant elevator that moves carbon down to the deep ocean. But that’s not all! When animals like zooplankton poop, that poop also sinks, taking more carbon with it. The deeper the carbon goes, the better it’s locked away. Down there in the dark, carbon stays hidden for hundreds or even thousands of years. It’s like storing treasure at the bottom of the sea!

The Twilight Zone – Where the Magic Happens

But wait—there’s more! Some zooplankton are big adventurers. At night, they swim up to the surface to eat phytoplankton, and when the sun rises, they dive back down into the twilight zone. This is a deep part of the ocean where it’s dark and mysterious. As they swim up and down, they carry carbon with them, helping it sink even deeper. This helps keep the carbon out of the atmosphere, which is important for keeping the planet cool.

Step 5: What If Carbon Stays Near the Surface?

Not all carbon makes it to the deep ocean, though. Sometimes, if phytoplankton and zooplankton get eaten near the surface, the carbon they have can escape back into the air. But when carbon sinks into the deep ocean, it stays there, far away from the atmosphere. That’s why it’s so important for carbon to sink—so it doesn’t come back up!

Long-Term Storage – Carbon’s New Home

Once the carbon is deep in the ocean, it’s like it found a new home. It stays down there for a long, long time, far away from the atmosphere. This helps keep Earth’s climate cool and makes sure there’s not too much CO2 in the air. The ocean is like a giant storage locker for carbon, and it helps protect our planet. Since humans started burning fossil fuels, the ocean has absorbed about 30% of all the extra CO2 we’ve put into the air. That’s why the ocean is such an important part of the carbon cycle!

So, how do scientists know all this? Well, NASA has a special spacecraft called PACE that watches the ocean from space! It looks at the ocean’s color, which changes when phytoplankton are present. By watching these colors, PACE helps scientists see where phytoplankton are, how much CO2 they’re taking in, and how the carbon is moving through the ocean. It’s like having a superhero watch over the ocean’s carbon adventure from space! (animated superhero astronaut)

Give a MCQ test

1. What percentage of human-made CO2 ends up in the ocean?

10%
25%
50%
75%

2. What process do phytoplankton use to convert CO2 into food?

Photosynthesis
Respiration
Digestion
Decomposition

3. How much of the oxygen we breathe is produced by phytoplankton?

10%
25%
50%
75%

4. What are zooplankton?

Tiny ocean plants
Tiny ocean animals
Fish
Seaweeds

5. What happens to the carbon when zooplankton eat phytoplankton?

It is absorbed by the ocean water
It disappears
It gets passed along the food chain
It is released back into the air

6. What is the “biological pump” in the ocean?

A machine that moves carbon around
The process of moving carbon to the deep ocean
A type of fish that eats phytoplankton
A weather phenomenon

7. What happens when zooplankton poop?

Carbon escapes into the air
It sinks to the bottom of the ocean, taking carbon with it
The poop floats on the ocean’s surface
It is eaten by small fish

8. What part of the ocean do zooplankton dive into during the day?

Surface layer
Deep ocean
Twilight zone
Coral reef

9. What happens when carbon stays near the ocean’s surface?

It escapes back into the atmosphere
It sinks to the bottom
It turns into oxygen
It gets absorbed by fish

10. How does NASA's PACE spacecraft help scientists study the ocean’s carbon cycle?

By watching the ocean’s temperature
By measuring ocean currents
By observing the color of the ocean to detect phytoplankton
By counting fish in the ocean