How to turn your backyard into a carbon sink

It can sometimes seem like a climate-wise life entails less of everything: less travel; fewer animal products; fewer children. But alongside cutting our personal emissions, there are plenty of ways we can proactively help remove carbon from the atmosphere, too.

One such solution might be right in your backyard. If you have access to any kind of outdoor space, you can set it up to stash carbon, while decorating your doorstep and providing you with food-miles-free meals too. How?

“I can sum it up in just one sentence,” says botanist Ginny Stibolt, co-author with landscape architect Sue Reed of the practical guide Climate-Wise Landscaping. “We need to stop treating our soil like dirt.”

There is four times as much carbon stored below ground as in all of the world’s vegetation. That’s because healthy soil is full of fungi and microorganisms that feed on carbon from dead plants and animals and from the roots of living plants.

The carbon molecule chains – called humus polymers – become longer and more stable as the organisms digest and use them, so the molecules within them are less likely to leak back into the atmosphere. Given the right conditions, they can even attract atmospheric carbon molecules down into the soil to join them.

And now, let’s dig in.

Step 1: Back off

This process is first and foremost about doing no harm, say Stibolt and Reed. The over-watered, sprayed monoculture that constitutes a manicured lawn is disastrous for microbial and fungal life.

You don’t have to lose the lawn entirely, but leaving the grass to grow a bit longer will allow it to develop deeper root systems and accommodate more microbial and fungal life.

Letting other species like clover – and the occasional ‘weed’ – to grow alongside grass will help boost the diversity of underground life too. It’s also crucial to avoid pesticides and insecticides as much as possible to create a thriving below-ground backyard ecosystem, says Stibolt.

Step 2: Feed your soil, build your beds

Once we’ve backed off on lawn care, what can we do to boost our soil health and trap more carbon in the process? Feed it compost, that’s what. You can compost all kinds of organic matter: food scraps, coffee grounds, grass clippings and tree trimmings.

Variety is key here: try for a range of soft, moist nitrogen-rich things, like kitchen waste or green leaves, and dry carbon-rich things, such as small branches or sawdust. If your pile starts to smell bad, it’s likely not getting enough air: add more dry, stalky things to create air pockets, and sprinkle wood ash to neutralize the smell.

As an important side note, in addition to nourishing your backyard ecosystem, composting your food scraps is an important way to cut your emissions. When food waste goes into landfills, it releases methane, a greenhouse gas that’s at least 28 times more potent than carbon dioxide. Eight percent of global emissions currently comes from food waste.

According to modeling by Project Drawdown, worldwide adoption of composting could reduce emissions by 2.3 billion tons over the next 30 years – as well as help us feed the world on less land by boosting soil productivity.

You can make your compost in a purpose-built bin or container, or you can do it right where you’re hoping to plant things. Just lay wet newspaper or cardboard directly onto the ground, and pile your compost on top. It will gradually break down into carbon-rich soil. No-dig beds like this will help leave those crucial carbon chains and fungal and microbial habitats – and your all-important back muscles – intact.

Step 3: Boost biodiversity

“Mother Nature doesn’t like to grow only one thing. So if you try to do that, she’ll do her best to plant all kinds of other things there,” says Stibolt. Greater diversity of plants above-ground improves the diversity of microbes and fungi underneath.

This takes us to the fun part: choosing what you want to grow in your backyard. Eric Toensmeier, author of The Carbon Farming Solution, recommends choosing some woody perennials like fruit trees, if you have the space, because they grow huge root systems and sequester large amounts of carbon in their trunks and branches.

Layering your plants into ‘food forest’-style systems – rather than individual plants with bare ground around them – also helps to sequester as much carbon as possible. 

Stibolt also recommends prioritizing plants that are native to your area. These are likely to grow happily in local conditions with minimal help and might be some of the strongest adaptors to climate change.

What’s more, by planting endemic species, you’re helping conserve biodiversity, which is crucial for healthy ecosystems. Stibolt herself has been enjoying growing beautyberries (Callicarpa americana), which are native to her home in the U.S. state of Florida. She uses them in baking, though she says she feels guilty for ‘robbing’ the birds that feast on them over winter.

In general, Stibolt also recommends growing the kinds of foods that you like to eat. “Buying local food makes a big difference [for reducing carbon emissions],” she says. “So if you can grow even some of your food on your porch, in pots, that’s important.”

Once you’ve planted, cover any remaining bare earth with mulch – organic material such as grass clippings, fallen leaves, straw or hay. This will inhibit weed growth and stop water from evaporating so quickly, so you won’t need to water your backyard so frequently. 

Step 4: Spread the word

Toensmeier’s own modest 405-square-meter garden in the U.S. state of Massachusetts sequesters enough carbon to offset the carbon footprint of one American adult. The example is compelling.

“People are really panicking about climate change,” says Stibolt, “especially here in the U.S., in our current political climate. They’re not waiting on the government anymore; they’re looking for other ways to take action.” 

“And there is so much we can do ourselves [to sequester carbon],” she adds, “in whatever space we have. If we all did it, imagine the impact that would have!”