For climate-fighting farms, squeeze in some trees: study

Around the world, planting crops and grazing livestock often means cutting down trees — with disastrous impacts on the climate. But are forests and farms really at odds?

A groundbreaking new study from Conservation International says no — instead it points to ways for forests and farms to co-exist and fight climate change without cutting into food production. 

The world’s agricultural lands, researchers write, hold vast, previously untapped potential for storing potentially climate-warming carbon — in fact, they could trap as much carbon as the global emissions of all cars combined. 

“The findings are crucial for global climate efforts because they present a large-scale, cost-effective carbon removal strategy that can be implemented within existing agricultural landscapes,” said the study’s lead author, Starry Sprenkle-Hyppolite, who heads Conservation International’s forest restoration science. “Even adding just a few trees per hectare could have a massive impact when applied across the 2.6 billion hectares identified in our study.”

What will it take to pull this off? Sprenkle-Hyppolite explains how farms could help fight climate change — without giving up a huge chunk of their lands. 

Conservation News: Let’s start with the basics — why do farms and trees belong together?

Starry Sprenkle-Hyppolite: The thinking in modern agriculture is that crops need sun and water, and trees compete for both — so let’s cut them down. But this has devastating impacts on nature and climate. In fact, agriculture is responsible for 90 percent of all tropical deforestation, a major cause of climate-warming greenhouse gasses.

But in many places — particularly where traditional ways of agriculture are practiced — people have developed systems where trees and agriculture work together and are more resilient for it. For example, in Spain you have the dehesa system, where pigs and cattle forage freely in oak savannas and ancient olive groves are sown with wheat and other crops. And of course, there are many examples in the tropics, where coffee is often grown alongside cocoa, Brazil nut or acai. 

It makes sense. The trees improve soil health and water quality while also attracting bees, birds and other pollinators. At the same time, they protect crops and livestock against extreme heat and drought by providing shade and increasing moisture in the soil. As climate change accelerates, we need trees more than ever.

And while we can’t go back and prevent trees from being cleared for agriculture, that doesn’t mean we’re stuck. There is enormous untapped potential to incorporate trees on existing farms. So, we decided to map the maximum number of trees that farmlands can sustain without hurting crop yields. 

And what did you find?

SSH: We found that 54 percent of agricultural lands — an area equivalent to the total land area of North America — could plant more trees, without sacrificing food security. That could translate to stashing away 3.3 billion tons of carbon per year — an amount greater than the global annual emissions from cars. 

And we’re not asking farmers to give up a huge chunk of their land to do this. We’re talking about working in the margins — planting a relatively small number of trees over large areas of land, such as the outer edges of farms. The United States, China and India have the highest potential because of their expansive industrial farmland and the temperate and tropical climates that are ideal for tree growth.

Of course, this is not a one-size-fits all situation. The number and types of trees must be tailored to individual farms’ specific climate and situation. We’re not talking about putting trees in deserts. We’re not talking about planting trees that farmers would need to water. These trees should be able to survive on their own and suit the climate they’re in. We took these factors into consideration and created a framework to help landowners, conservationists and policymakers understand what’s possible.

Sounds like a win — so what’s stopping farmers from planting more trees?

SSH: For one, we’re asking people to change the way they’ve farmed for generations. Despite the benefits, that’s never an easy switch. Also, there are policies and farming subsidies to consider. Some countries don’t favor agroforestry practices — there are even laws that say cropland cannot have trees on it. 

But I want to be clear, we’re not talking about implementing a new technology. Trees are readily available and relatively easy to plant. People have been practicing agroforestry for thousands of years. Much of the challenge lies in changing mentalities and the preconceived notion that land must be completely cleared to be productive. 

What’s next?

SSH: We’re focusing now on how we can take this research and make it actionable. To start, policies must make planting trees more attractive to farmers — and countries’ climate action plans must incorporate these practices. The study’s maps can be used by policy makers to target areas that are best suited for more trees.

We’re also thinking about how farmers can make money by planting trees on their land. That could come from selling credits tied to the amount of carbon sequestered by trees, or selling the fruit or other products from the trees they plant.

In Canada some growers alternate hardwood nut trees with poplar trees. Poplar trees grow very fast and big — meaning, they store lots of carbon quickly — and the nuts can be sold for profit. That’s just one example, there are countless opportunities to maximize the relationship between trees and agriculture. Our study looked at about 90 varieties of trees, but there are thousands of types of trees that could be used.

My hope is that this study makes people re-evaluate what is possible. Ultimately, this is really about the climate crisis. We need to find rapid ways to scale carbon sequestration and this — because of the amount of land it is possible on — is the most extensive and ready-to-go solution that the world has for carbon removal.

Further reading:

Mary Kate McCoy is a staff writer at Conservation International. Want to read more stories like this? Sign up for email updates. Also, please consider supporting our critical work.