Carbon and carbon dioxide

Carbon

Carbon (C) is a chemical element that is found in many forms as an energy source for building things such as:

• our bodies (18% of a person) – in our DNA, muscles, bones and more

• the atmosphere – as CO₂

• rocks, soils and the Earth’s crust

• fossil fuels – for example, petrol and diesel

• oceans

• animals

• plants

• buildings

• the atmosphere.

In the atmosphere, carbon can be found as carbon dioxide (CO₂), carbon monoxide (CO) and methane (CH₄).

Carbon dioxide

Carbon dioxide, also called CO₂ (pronounced see-oh-two), is the most important of the greenhouse gases as it is emitted in large quantities and has a long-lasting influence.

CO₂ stays in the atmosphere for thousands of years (also known as the atmospheric lifetime). This is one of the reasons why it builds up in the atmosphere and why we must reduce emissions.

Other greenhouse gases have shorter lifetimes or much smaller concentrations in the atmosphere. For example, 0.04% of the atmosphere is CO₂, while methane accounts for 0.00003%. Even such small quantities are enough to trap lots of heat. 

Carbon dioxide in the atmosphere is part of the carbon cycle. Carbon moves around the Earth between these different forms through the carbon cycle. The carbon cycle is the movement of carbon in the form of CO₂ into and out of the atmosphere.

Global warming potential 

Global warming potential (GWP) is a way to compare how much heat a greenhouse gas can trap in the atmosphere over a period of time. It helps us compare the different greenhouse gases.

Related articles

• Carbon cycle

• The ocean and the carbon cycle

• Carbon dioxide in the atmosphere

• Carbon – life’s framework element

• The carbon cycle and climate change – key terms

• Climate change and the carbon cycle – kuputaka

• Trees, seas and soil

Related activities

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

• Carbon cycle quiz

• Carbon cycle – three-level reading guide

Related media

• Carbon cycle – interactive

• SLH and the carbon cycle – webinar

Useful links

• How carbon affects nearly everything on Earth – including our future – video by Smithsonian’s National Museum of Natural History

• The carbon cycle is key to understanding climate change – video, The Economist

• Overview of greenhouse gases – resource, US Environmental Protection Agency

• The greenhouse effect – video, US Environmental Protection Agency