How Much CO2 Does Earth Absorb?

Written By Teacher: Teresa Pettitt-Kenney

Hi there! My name is Teresa and I just finished my Bachelor's degree in Environmental Science and am excited to pursue environmental education in the future! I am extremely passionate about climate change, equitable climate action, and how education can work to address these issues. 

Whenever there are headlines about climate change, you can safely assume that carbon dioxide emissions will be mentioned. This greenhouse gas plays an important role in the changes happening to our planet, but carbon dioxide has driven climate before humans ever existed. Understanding the carbon cycle and the natural processes carbon dioxide follows in the atmosphere can help students better understand earth systems and how humans are contributing to such an impactful change. As you expand your knowledge surrounding carbon dioxide and the carbon cycle, consider implementing resources to expand your students' perspectives as well. Build background with this All About Carbon article, or dive in with hands-on activities, like this 3-part Carbon in the Atmosphere Lab that explores the greenhouse effect and historic temperature and carbon dioxide trends. 

Written By: MIT Environmental Solutions Initiative

The MIT Climate Change Engagement Program, a part of MIT Climate HQ, provides the public with nonpartisan, easy-to-understand, and scientifically-grounded information on climate change and its solutions.

The Earth’s natural carbon cycle moves a staggering amount of carbon dioxide (CO2) around our planet, says Daniel Rothman, MIT professor of geophysics. Some parts of the planet, such as the oceans and forests, absorb carbon dioxide and store it for hundreds or thousands of years. These are called natural carbon sinks. Meanwhile, natural sources of CO2 such as undersea volcanoes and hydrothermal vents release carbon. Altogether the planet absorbs and emits around 100 billion metric tons of carbon through this natural cycle every year, Rothman says.

That's equivalent to over 350 billion tons of CO2. (Scientists often measure the carbon cycle in terms of the weight of carbon atoms, not whole molecules of carbon dioxide, because the carbon has the same weight no matter what form it takes as it moves between plants, ocean, atmosphere, and other parts of the natural world.)

This natural movement of carbon dwarfs humanity’s contribution: it amounts to ten times as much CO2 as humans produce through activities such as burning fossil fuels.