Greenhouse Effect: Keeping the Balance

The Short Answer:

How do we keep the right balance of greenhouse gases in our atmosphere?

Scientists describe the carbon cycle in terms of sources (parts of the cycle that add carbon to the atmosphere) and sinks (parts of the cycle that remove carbon from the atmosphere). The carbon cycle’s sinks and sources help to regulate the amount of greenhouse gases in our atmosphere.

Greenhouse Gases

Besides CO₂ there are other greenhouse gases. These include water vapor, methane, nitrous oxide, and ozone. Without any greenhouse gases, Earth would be an icy wasteland. Greenhouse gases keep our planet livable by holding onto some of Earth’s heat energy so that it doesn’t all escape into space. This heat trapping is known as the greenhouse effect.

Just as too little greenhouse gas makes Earth too cold, too much greenhouse gas makes Earth too warm. Over the last century, humans have burned coal, oil, and gasoline in our cars, trucks, planes, trains, power plants, and factories. Burning such fossil fuels produces CO₂ as a waste product. Putting so much new CO₂ into the air has made Earth warmer. If we continue on our current path, we will cause even more warming.

Finding a Balance

CO₂ is a big part of the carbon cycle. The carbon cycle traces carbon's path from the atmosphere, into living organisms, then turning into dead organic matter, going into the oceans, and back into the atmosphere. Scientists describe the cycle in terms of sources (parts of the cycle that add carbon to the atmosphere) and sinks (parts of the cycle that remove carbon from the atmosphere).

The key to keeping everything in balance is for the sources and sinks to have the same amount of CO₂.

The most important sinks are the ocean (which includes the seawater itself, the organisms living there, and the sediments on the sea floor) as well as plants and soil on land. The ocean stores most of the world's carbon, but forests are really important too. Forests and oceans each remove around one-fourth of the carbon we humans have added to the atmosphere.

Related NASA Missions

Aqua

Aura

OCO-2

Keeping an Eye on Greenhouse Gases

Artwork of NASA's Aura spacecraft, which carries the Tropospheric Emissions Spectrometer. Credit: NASA/JPL

NASA has been able to look at greenhouse gases, including CO₂, ever since the Atmospheric Infrared Sounder (AIRS) instrument was launched aboard the Aqua satellite in 2002, and the Tropospheric Emissions Spectrometer (TES) instrument was launched aboard the Aura satellite in 2004. Both instruments measure CO₂ in only one part of the atmosphere—the part nearest Earth’s surface, called the troposphere. Both instruments monitor many other things in the atmosphere as well.

For a more complete look at CO₂ as it moves through the carbon cycle, especially near the ground, NASA needed a new tool.

Artwork of NASA's Orbiting Carbon Observatory-2. Credit: NASA/JPL

That tool is the Orbiting Carbon Observatory-2 (OCO-2). It is giving us the best view ever of CO₂ in the atmosphere all around the world. Passing rapidly from the North Pole to the South Pole, the OCO-2 satellite measures the planet's atmospheric CO₂ every 16 days. OCO-2 will make many more measurements of the changes in CO₂ near Earth’s surface. OCO-2 will give us a clear picture of how carbon sinks and sources are being altered by human activity.

Illustration of a video game controller.