The global carbon cycle

The carbon cycle contains sources and sinks of carbon dioxide from the atmosphere. 

A carbon sink is a system that takes in more carbon from the atmosphere than it releases. A carbon source is a system that releases more carbon than it takes in.

These sources and sinks control the amount of carbon in the form of carbon dioxide (CO₂) that is in the atmosphere.

Did you know volcanoes are also part of the carbon cycle?! When the magma rises to the surface and erupts, the carbon dioxide escapes into the air, which is a natural geological process, but this contribution is still much smaller compared to human activities like burning fossil fuels.

What is a carbon footprint?

A carbon footprint is the total amount of CO₂ and other greenhouse gases that are released into the atmosphere because of human activities.

It includes things like the energy we use, the food we eat, the products we buy and the travel we do. The bigger the carbon footprint, the more it contributes to climate change. Reducing our carbon footprint means making choices that are less harmful for the planet.

Related articles

• Carbon cycle

• The carbon cycle and climate change – key terms

• Climate change and the carbon cycle – kuputaka

• The ocean and the carbon cycle

• Carbon dioxide in the ocean

• Carbon dioxide in the atmosphere

• The Southern Ocean’s ecological richness and significance for global climate

Related activities

• Drive it Down! – climate change and carbon cycle quiz

• Carbon cycle quiz

• Carbon cycle – three-level reading guide 

• Fossil Atmospheres – Zooniverse – citizen science project

Related media

• Increasing atmospheric carbon dioxide – video

• Southern Ocean carbon sink – video

• Carbon dioxide exchange – video

• SLH and the carbon cycle – webinar

Useful link

• Feedback – School Journal Level 4 2020