How Does Rock Weathering Reduce CO2?

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. 

Teaching about climate change can get heavy sometimes, so focusing on climate solutions can be a great way to shift the narrative in your classroom. Enhanced rock weathering is scientists’ way of using Earth’s natural processes to reduce CO2 in our atmosphere. Not only will your students be empowered by an exciting climate solution, but they will also learn about earth systems like geology and the carbon cycle. Start building understanding with videos and worksheets, like the ones included in this Earth Systems Activity.

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.

Enhanced rock weathering is a strategy to help address climate change by taking carbon out of the air and storing it in rocks. It is one of several “carbon removal” techniques that target carbon dioxide (CO2), the most important climate-warming greenhouse gas humans have been adding to the atmosphere.

Rocks and the natural carbon cycle

Enhanced rock weathering builds on a natural part of our climate system. As rocks are worn away by rain (or “weathered”), they release elements like calcium and magnesium. Meanwhile, CO2 in the air goes through other natural reactions to become carbonic acid (found in rain) or bicarbonate (found in the ocean). When these different compounds meet, they join to form new rocks like calcium carbonate, better known as limestone.

In this way, rocks help draw CO2 out of the atmosphere.

Natural rock weathering takes place over many millions of years: far too slow to help against today’s human-caused climate change. But beginning in the 1990s, scientists concerned about the buildup of CO2 in our atmosphere started to suggest ways to speed rock weathering up. This “enhanced” weathering would aim to take hundreds of millions or billions of tons of carbon out of the air every year.