Carbon crisis: What if the ocean lost all of its life?

It’s a chilling thought – what would happen if every living thing in the ocean vanished? From microscopic plankton to blue whales, ocean life plays a huge role in how our planet stays in balance. A new study takes this thought experiment seriously and finds surprising insights into how the death of marine life can affect carbon absorption.

The scientists behind this research are from NORCE and the Bjerknes Centre for Climate Research in Norway. Using the Norwegian Earth System Model (NorESM), they created detailed simulations to explore how the planet’s climate would respond without ocean life.

Their goal was to figure out how much we depend on living organisms in the sea to manage carbon dioxide in the atmosphere.

The ocean’s role in carbon storage

The ocean isn’t just a body of water – it’s a carbon sponge. It soaks up about 25% of the carbon dioxide that humans release into the atmosphere each year. A big part of this carbon storage is thanks to life in the ocean.

Tiny plankton consume carbon near the surface. When they die, they sink, carrying that carbon to the deep ocean. This process is known as the biological carbon pump. But what happens when you remove life from the equation?

In the study, researchers ran two versions of their simulation: one with marine life, and one without. When they took marine life out of the picture, they found that atmospheric CO2 levels jumped by about 50%.

“But the simulation showed that in a scenario where all marine life is eradicated, land ecosystems will absorb about half of the carbon that the ocean cannot take up without marine life,” said study co-author Damien Couespel.

Link between ocean life and carbon

The researchers say this study reveals a missing piece in how we understand the climate system. For years, the focus has been on how the ocean’s chemistry and temperature affect carbon absorption. But this study suggests that biology plays a much bigger role than previously recognized.

“We have long understood that the biological carbon pump plays a crucial role in keeping atmospheric CO2 levels low. However, most studies have overlooked the interaction with Earth’s ecosystems. Our research suggests that land ecosystems compensate if marine life is eradicated and the ocean’s ability to absorb CO2 is thus limited,” said Jerry Tjiputra, lead author of the study.

The team didn’t stop there. They also simulated the Earth’s climate in two time periods: before humans started burning large amounts of fossil fuels (pre-1850) and in a high-emission future. Again, they ran the model with and without marine life.

“In all cases, much more CO2 will remain in the atmosphere if all marine life were removed. This is because, without living organisms consuming carbon at the ocean surface, the carbon content at the ocean surface is much higher. This limits the ocean’s ability to absorb more CO2,” explained Tjiputra.

Rethinking how the ocean works

The results challenge some long-standing ideas. “Our results thus challenge the paradigm that the ocean’s carbon uptake is mainly driven by physical and chemical processes, rather than biological ones. An ocean without life would weaken its ability to absorb carbon emissions,” said Couespel.

If marine life disappeared, the world would likely warm faster. The ocean would lose its buffering capacity, and we might trigger even more feedbacks that drive temperatures higher.

Ocean life and climate change

No one expects the ocean to suddenly become lifeless. But this “what-if” exercise offers important lessons. The researchers believe it shows how marine and land ecosystems work together to manage our climate.

“We have learned that marine and terrestrial life work together to regulate our climate and that marine life is a key player in shaping the course of climate change. Our research clearly underscores that there is a link between the protection of marine ecosystems and combating climate change,” said Tjiputra.

“A healthy ocean buys us time. Damage to marine ecosystems can significantly accelerate human-caused climate change and further challenge our ability to meet the goals in the Paris Agreement. Preserving the function of marine ecosystems is essential for mitigating climate change and its associated risks.”

This simple yet startling study reminds us that life in the ocean isn’t just there for beauty or biodiversity – it’s helping stabilize the planet. And protecting it may be one of our best tools in the fight against climate change.

The full study was published in the journal Nature Communications.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–