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Cutting carbon

The surprising science of soil

Illustration of some happy critters and tree roots in soil.

It may not be as glamorous as trees or the ocean, but soil is a carbon capture superhero all the same. Dirt locks carbon out of our atmosphere longer than the forest or the sea. And that means less carbon in the air contributing to global climate change. Which is pretty fabulous for something so, well, dirty.

Trees and other plants are famous for taking in carbon dioxide from the atmosphere to use for their own energy. Like ordering takeout on an empty stomach, not all of that food gets used. Some of it makes its way down into the soil, where a rich ecosystem of tiny microbes feast on those carbon leftovers.

But they aren’t alone. As living things die and decompose, they are added to the mix. Although it’s formally known as Soil Organic Matter or SOM, we like to think of it as the underground carbon party.

The underground climate hero

Every year, soil can take in up to 3 gigatons of carbon. That’s more than the ocean. And if left untouched, that carbon can stay locked up underground and out of the atmosphere for thousands of years. 

Soil stores carbon at different rates. Plants with lots of root fungi bring more carbon to the soil than plants without that fungus. Wetlands and bogs store more carbon than other landscapes. Land used for farming that's tilled regularly releases more carbon into the atmosphere. 

We thought that was pretty fascinating. Maybe even enough to say “yay” instead of “yuck” when we track mud inside on our shoes. 

Using soil to rethink farming 

Soil is clearly a big piece of the carbon cycle puzzle. Which means it can play an important role in finding new solutions for climate change.

Since the industrial revolution, we’ve converted many areas with natural carbon storage into farmland. In fact, we’ve churned up enough soil around the world to release up to 100 GT of carbon back into the atmosphere. Turns out, restoring this degraded land into rich soil ecosystems has the potential to lock away up to 3 billion tons of carbon every year. One way to do this is through regenerative agriculture. That’s a fancy name for farming that focuses on managing soil rather than crops.

These farms use free-roaming livestock, cover crops and other natural features to keep the land healthy and productive without the need for a till. That means a healthy, carbon-rich ecosystem below ground and a diverse, productive farm above ground. Talk about a win-win. 

Scientists estimate that regenerative farming could increase the carbon content of soil by up to 8% every year. There’s still a lot we can learn about regenerative farming, including how to make it easier for farmers to practice. And the more we learn about soil, the more we can learn about tools like regenerative agriculture to add to our climate fighting toolbelt.

If you enjoyed digging into this as much as we did, check out the resources listed below. Or head outside and say thank you to that pile of dirt in your back garden. We certainly will.

Resources

Yale on soil’s carbon storing powers

Nature on the science of how soil soaks up carbon

Project Drawdown’s take on regenerative farming

How to Save a Planet podcast episode on dirt’s potential as a climate change solution