How Will CO2 Emissions Affect Oxygen?

Written By Teacher: Emily Rogers

Emily has a bachelor’s degree in English and French and a master’s degree in library and information science. She spent seven years teaching information evaluation and research skills as a school librarian in K-8 public schools. As a lifelong resident of Southern Louisiana, Emily has a particular interest in how climate change affects coastal regions. She hopes to connect educators with resources that will help them to teach their students about the disproportionately adverse effects of climate change on historically marginalized communities.

Aquatic ecosystems might not be the first thing that comes to your students’ minds when they think about oxygen, but decreased oxygen levels from increased CO2 emissions impact aquatic ecosystems the most. While it is important to teach students about the devastating effects of low oxygen levels on the oceans, it is equally as important to explain the vital role that the ocean plays in carbon sequestration. Do a hands-on experiment to learn how aquatic plants absorb CO2, or engage students in learning about promising solutions like seaweed farming. Understanding the causes as well as potential solutions will equip students with the knowledge they need to make informed decisions about how we can protect the Earth.

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.

Humans and virtually all animal life on Earth require oxygen to breathe. (Yes, even fish breathe oxygen.) Scientists around the world have found that the concentration of oxygen in our water and air is actually declining, says Prof. Andrew Babbin, an oceanographer and professor of chemical oceanography and marine microbiology at MIT Department of Earth, Atmospheric and Planetary Sciences (EAPS).

Why? The biggest culprit is the burning of fossil fuels.

First, let’s talk about the oxygen that’s in our air, which we and other animals breathe every day.

When we burn fossil fuels, carbon (C) combines with oxygen molecules (O2) to make carbon dioxide (CO2), which is a greenhouse gas that is the main contributor to climate change. This process traps the oxygen molecules that are in our air into the CO2–which means there’s less oxygen for life to breathe. This sounds worrisome, but it isn’t terribly concerning for most scientists, Babbin says. Oxygen makes up about 20% of the atmosphere, and even with all our carbon emissions, total atmospheric oxygen levels have only dropped “a very tiny fraction,”  he says.

In our ocean, it’s a different story. The ocean stabilizes the atmosphere in two important ways—it contains plankton and bacteria that produce somewhere between 50 to 80% of the world’s oxygen, and its water absorbs massive amounts of carbon—about one-third of the amount humans have put into the air since the Industrial Age—reducing the impact of fossil fuel combustion. As the planet gets hotter due to increased CO2 concentrations, oceans are also warming up. As liquids warm, they can’t hold as much dissolved gas. This means a warmer ocean can’t hold as much carbon or dissolved oxygen, which marine life relies on for survival.