Why Is Carbon Important?

The Short Answer:

Carbon is in carbon dioxide, which is a greenhouse gas that traps heat close to Earth. It helps Earth hold some of the heat it receives from the Sun so it doesn't all escape back into space. But CO₂ is only good up to a point – beyond that point, Earth's temperature warms up too much. NASA research satellites such as OCO-2 and OCO-3 are studying how carbon moves around the planet.

What is carbon?

Take a deep breath in. And breathe out. You just exhaled carbon dioxide!

This graphic depicts a black silhouette of a human exhaling carbon dioxide. White arrows illustrate the direction of the flow of CO<sub>2</sub> away from the human silhouette's mouth.

Humans exhale carbon dioxide. Credit: NASA/JPL-Caltech.

All living things on Earth contain carbon. Even you contain carbon. Lots of it! Like every other living thing on this planet, we are a part of Earth's carbon cycle. Plants take in CO₂. They keep the carbon and give away the oxygen. Animals breathe in the oxygen and breathe out carbon dioxide. Carbon, including carbon dioxide, has cycled into and out of the air for a long time. This cycling of carbon has stayed balanced over long periods of time.

This infographic demonstrates how carbon dioxide cycles through the environment through vegetation, soils, fires, and the burning of fossil fuels. A digital rendering of a flat landscape shows the different sources of carbon on our planet. From left to right, the landscape shows green trees and vegetation, dark-colored pillars next to a factory building producing smoke plumes, a cow crazing, and lastly, a fire burning green trees and emitting a thick cloud of smoke. Above each of these elements are yellow up-and-down arrows depicting how carbon moves as a result of these processes.

The carbon cycle. Credit: NASA/JPL-Caltech.

What is carbon dioxide?

Carbon dioxide is an important gas for life on the planet. (Remember our deep breath in and out?) It is crucial to maintaining the protective blanket that is Earth's atmosphere. Carbon dioxide is often called "C-O-2" (pronounced see-oh-two) and written as "CO₂" because "C" stands for carbon and "O" stands for oxygen. Carbon dioxide is one of the primary greenhouse gases on Earth.

This graphic illustrates the elements that make up a carbon dioxide molecule: one carbon atom and two oxygen atoms.

Carbon dioxide is called CO₂ because it has two oxygen atoms attached to one carbon atom. This illustration of a carbon dioxide molecule shows a larger carbon atom (labeled with a C) between two oxygen atoms (labeled with an O). Credit: NASA/JPL-Caltech.

Greenhouse gases trap heat from the Sun. Without greenhouse gases, that heat would escape Earth's atmosphere and go back into space. Human activities, such as burning fossil fuels and cutting down forests, are changing the balance between how much carbon is in the air and how much carbon is stored in plants and the ocean. These activities cause the amount of CO₂ in the air to rise. Big increases in CO₂ in our atmosphere can negatively affect Earth's climate.

This graphic shows how the Sun's energy is captured inside of a greenhouse to keep plants warm. A yellow circle in the top left corner of the illustration, representing the Sun, emits light yellow arrows that travel into the illustration of a greenhouse. The greenhouse, seen growing green vegetation with red berries, is on top of snow and to the right of a snowman with a carrot nose and black top hat. The yellow arrows depict how heat energy enters a greenhouse and is trapped inside, heating the interior while the outside environment stays cold.

A greenhouse traps the Sun's energy inside and keeps the plants warm. Credit: NASA/JPL-Caltech.

This graphic shows how Earth's atmosphere acts as a greenhouse for the Sun's energy. In this illustration, the Sun appears in the top left corner. Earth is in the bottom right corner, outlined by a thick blue ring labeled "Atmosphere." Three arrows of varying colors travel from the Sun toward Earth. One arrow points directly at the atmosphere, but does not cross into the atmosphere. The second (middle) arrow penetrates the outline of the atmosphere and points directly at Earth. The last and rightmost arrow is traveling to the atmosphere and bouncing off, sending the arrow into the opposite direction. In the bottom left corner of the illustration is a thermometer. These arrows demonstrate how the Sun's heat energy either stops before it reaches the atmosphere, penetrates and stays within the atmosphere, or bounces off the atmosphere back into space.

Earth's atmosphere traps some of the Sun's heat, preventing it from escaping back into space at night. Credit: NASA/JPL-Caltech.

So is carbon dioxide bad?

Here's the big, important thing about CO₂: It's a greenhouse gas. That means CO₂ in the atmosphere traps heat close to Earth. It helps our planet hold onto some of the heat it gets from the Sun so the energy doesn't all escape back into space.

This animated graphic shows how Earth's atmosphere acts as a greenhouse for the Sun's energy. Titled "The Greenhouse Effect," this gif uses text and animated arrows to show how the Sun's heat energy interacts with Earth's atmosphere. The text in the gif says, "Sunlight reaches the Earth. Some energy is reflected back into space. Some energy is absorbed and re-radiated as heat. Most of the heat is absorbed by greenhouse gases and then radiated in all directions, warming the Earth."

This animated graphic shows how the greenhouse effect works in Earth's atmosphere. Credit: NASA/JPL-Caltech.

If it weren't for this greenhouse effect, Earth's ocean would be frozen solid. If not for the greenhouse effect, Earth would be an ice ball! Earth would not be the beautiful blue and green planet of life that it is.

These side-by-side pictures of Earth compare what our planet would look like if Earth's atmosphere did not act like a greenhouse! The picture on the left is an illustration of what Earth would look like if we did not have the greenhouse effect. This image shows a planet covered with white ice. The planet is overlaid with a circle-backslash symbol – a red circle with a 45-degree diagonal line inside the circle from lower-left to upper-right. The picture on the right is a real image of Earth, a planet of vivid greens and blues thanks to the greenhouse effect.

If it weren't for the greenhouse effect, Earth would look like the picture on the left: an ice ball! But our planet is full of life and liquid water because of the greenhouse effect. Credit: NASA/JPL-Caltech.

So, CO₂ and other greenhouse gases are good — but only up to a point. CO₂ is so good at holding in heat from the Sun that even a small increase in CO₂ in the atmosphere can make Earth even warmer.

These graphics show the good (natural) and the bad (dangerous and less natural) sides of carbon dioxide. The graphic on the left describes the good and natural effects of carbon dioxide: "Made up of carbon and oxygen, CO<sub>2</sub> is all around us naturally. It comes from decaying and living organisms, and from volcanoes." The graphic on the right describes the bad and less natural effects of carbon dioxide: "CO<sub>2</sub> is released when burning fossil fuels such as coal and oil. This greenhouse gas is the most important contributor to human-caused global warming."

The two sides to carbon dioxide. Learn more about the different greenhouse gases here! Credit: NASA/JPL-Caltech.

Throughout Earth's history, whenever the amount of CO₂ in the atmosphere has gone up, the temperature of Earth has also gone up. And when the temperature rises, CO₂ levels in the atmosphere increase even more, mostly because of the role the ocean plays in the carbon cycle. As ocean temperatures increase, oceans release stored carbon dioxide into the atmosphere – like a glass of soda losing its bubbles on a warm day.

This graphic shows how carbon dioxide has gone up and down over the last 800,000 years, with levels being higher than ever following the Industrial Revolution.

This graph shows how atmospheric CO₂ has increased since the Industrial Revolution. Credit: Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO₂ record.

How is NASA learning about carbon dioxide?

How is our planet handling this change to one of the key elements of life on Earth? To answer that, we need to keep a close eye on carbon. We need to know how and where it is entering and leaving the atmosphere and how it is interacting with weather and climate.

NASA's research satellites are studying how carbon moves around the planet.

NASA's Orbiting Carbon Observatory 2, or OCO-2, launched in 2014 to measure CO₂ to better observe Earth's carbon cycle. OCO-2 investigates important questions about carbon dioxide on Earth all the way from space! NASA's OCO-2 also helps explore how measurements from space can predict future CO₂ increases and its impact on Earth's climate.

This illustration shows an artist's rendition of the OCO-2 satellite taking carbon dioxide measurements all the way from space. The spacecraft says in a speech bubble, "I study carbon on Earth all the way from space!"

An illustration of OCO-2 taking carbon dioxide measurements on Earth all the way from space. Credit: NASA/JPL-Caltech.

Using technology like OCO-2, we can measure and map carbon dioxide from space to help us understand the interaction between carbon and climate.

Check out the Climate Time Machine to see how CO₂ and temperature have changed together throughout history.

Illustration of a video game controller.