Carbon Sequestration Explained: How Carbon Dioxide is Removed from the Air

Science & Tech
June 4, 2021
Avely Pütsep

“There’s no time to wait! Time is ticking! Global warming isn’t stopping unless we take action!” The slogans are everywhere these days.

What part does carbon sequestration play in the ongoing climate crisis? Let’s find out together.

In this article we’ll explain:

  • What carbon sequestration is
  • Its impact
  • Carbon sequestration examples
  • Geological vs biological CO2 sequestration
  • How to calculate carbon sequestration

Want to know more about carbon before diving into carbon sequestration? Read our Carbon Explained blog post.

What is carbon sequestration?

Removing carbon dioxide from the atmosphere and storing it is known as carbon sequestration.

Put simply: capturing carbon + storing it = carbon sequestration

It’s one method of reducing the amount of CO2 in the atmosphere, which comes from extensive fossil fuel burning and other harmful actions. Carbon sequestration is used to reduce global climate change.

Carbon sequestration can be natural or artificial, biological or geological.

Carbon can be sequestered to be held in solid or liquid form.

30% of carbon humans have emitted through fossil fuels is absorbed by the upper layer of the ocean.

What are the impacts of carbon sequestration?

Up to 30% of the carbon humans have emitted through fossil fuels is absorbed by the upper layer of the ocean. The result? 📈 The ocean’s acidity levels keep rising, making it harder for marine animals to build their shells.

A great deal of carbon is being sequestered by grasslands, forests, and farms. Hard work is being put into keeping landscapes vegetated and soil hydrated so plants can continue sequestering carbon.

About 45% of CO2 stays in the atmosphere, heating our planet. If it wasn’t for carbon sequestration, the percentage of carbon staying in the atmosphere would be even higher.

What are some examples of carbon sequestration?

Carbon sequestration examples include geological and biological carbon sequestration.

What’s the difference between geological and biological carbon sequestration?

The difference between geological and biological sequestration is where the carbon is stored.

  • Geological CO2 sequestration: carbon is stored underground or in rocks.
  • Biological CO2 sequestration: carbon is stored in soil, the ocean, aquatic environments, and vegetation like grasslands and forests.

More detail on both coming up.

What is geological carbon sequestration?

Geological carbon sequestration is the process of storing carbon in underground geological formations or rocks.

How does carbon sequestration work? Keep reading to find out!

To store carbon for a long time it is injected into porous rocks. It’s called geological carbon sequestering.

What are some examples of geological carbon sequestration?

Examples of geological CO2 sequestration include technological methods, such as graphene production, direct air capture (DAC), and engineered molecules.

Graphene production is the use of carbon dioxide as a raw material. Graphene is produced and used for tech devices like smartphone screens.

Direct air capture (DAC) - as the name suggests - is a way to capture carbon directly from the air by using advanced technology plants. This is, however, very expensive and energy-intensive, so it’s still too costly to implement on a big scale.

Engineered molecules is a method scientists are still working on. With this method, molecules can change shape by creating new kinds of compounds that can single out and capture carbon from the air.

How does the geological carbon cycle work?

Step 1: capturing of CO2

Typically, carbon capture comes from an industrial source like:

  • Steel or cement production
  • Energy-related sources like power plants or natural gas facilities

Step 2: storing of CO2

To store CO2 emissions for a long time, they are injected into porous rocks.

Why is geological carbon sequestration used?

It’s been used as a way to use fossil fuels until other energy sources can be used on a large scale.

What’s the best carbon capture technology?

The best carbon capture technology isn’t actually a technology, it’s leaving alone one of the biggest carbon sinks: forests. After all, deforestation numbers have been out of hand for years now, even though forests absorb twice the amount of carbon as they emit.

The best carbon capture technology is leaving alone one of the biggest carbon sinks- forests.

How deep must CO2 be buried?

As you go deeper into the Earth’s crust, temperature and pressure start to change. At about 800m or below, the natural temperature and fluid pressures allow CO2 to remain in a supercritical condition. This means the storage of much bigger volumes of CO2 than on the surface of Earth.

Which area is the best for geologic carbon sequestration?

It’s difficult to choose one area as the best for carbon sequestration because it depends on the “best for what exactly?”.

However, one answer is the Coastal Plains region, which includes coastal basins from Texas to Georgia. The area accounts for 2 000 metric gigatons or 65% of the storage potential.

Other areas with significant storage capacity include Alaska and the Rocky Mountains-Northern Great Plains.

What is biological carbon sequestration?

Biological CO2 sequestration is the storage of carbon dioxide in soils and oceans, as well as vegetations like grasslands and forests. These aren’t just important ecosystems for protecting biodiversity, they can also help us achieve carbon neutrality.

What are some examples of biological carbon sequestration?


  • Oceans absorb around 25% of humanity’s carbon footprint annually. Deep ocean is the largest carbon sink.
  • Parts of the ocean that are colder and richer with nutrients absorb more carbon. Therefore polar regions are more likely to be carbon sinks.
  • It’s important to know that oceans emit carbon, too. But they make it up by storing carbon - and way more than they emit.

Forests and grasslands

  • The MVPs: forests absorb twice as much carbon as they emit every year! Forestry carbon sequestration has a key role in halting climate change.
  • Around 25% of global CO2 emissions are sequestered in forests, grasslands, and rangelands.
  • However, when plants die or leaves and branches fall off, the carbon that was stored there is either released into the atmosphere OR transferred into the soil, being sequestered there.


  • Soil carbon storage is crucial in mitigating climate change.
  • Carbon is sequestered in soil through plants and photosynthesis.
Forests, grasslands, and rangelands sequester around 25% of global CO2 emissions.

How do you calculate carbon sequestration?

Start by determining the total green and dry weight of the tree, then determine the weight of carbon in the tree. From that, you can calculate the weight of carbon dioxide sequestered in the tree.

Easy! Well, not actually. If you want to learn more, check this link for examples of CO2 calculations.

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