How Do CO₂ Levels Affect Climate?

Written By Teacher: Liz Ransom

As a High School Spanish teacher and student newspaper advisor, Liz has taught for over 20 years and has served as World Languages Department Chair and K-6 summer camp activities leader. She has worked in Ohio, Maine, New Jersey, Maryland, and Chile.

The topic of CO₂ levels might come up in a variety of contexts for teachers and students addressing the climate impacts of daily activities. For example, this 3-5 grade interdisciplinary unit on transportation explores CO₂ emissions data. These 6-8 grade lessons look at greenhouse gas emissions resulting from food waste and household energy use. Both K-2 students and high school students can learn about clothing and climate impacts. This climate change explainer will give you the confidence to answer questions and dismantle misinformation about the relationship between CO₂ and climate change. Understanding the impact of CO₂ on climate empowers students to be part of effective climate solutions.

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.

When the last Ice Age (also called the “Last Glacial Maximum”) peaked around 20,000 years ago, carbon dioxide (CO2) levels were about 180 or 190 parts per million—less than half of where they stand today. At the time, the world was several degrees colder than in the preindustrial era and sea levels were roughly 400 feet below modern coastlines. That exposed much more land, which had less plant life on average than our current environment. Glaciers covered a quarter of the Earth's land surface, compared to about 10 percent today.

“We know pretty well what the climate looks like with lower CO2, because of all the work that's been done to understand past ice ages,” says David McGee, an associate professor in the MIT Department of Earth, Atmospheric and Planetary Sciences. “Very consistently, throughout Earth's history when CO2 has been low, we've had big ice sheets at the poles and overall colder global temperatures.”