July 09, 2019 5 min read

A Trillion Trees Could Save the Planet

Scientists have always speculated about how trees can help end the current climate crisis, but the question has always been how many. A new study from the Crowther Lab out of Swiss University ETH Zurich, has finally come up with an answer: 1 trillion more trees on Earth could sequester more than 60% of anthropogenic carbon emissions.

See The Power of Trees

It has long been understood that trees and forests remain the best strategy humanity has for cleansing our atmosphere of the harmful greenhouse gas carbon dioxide, a key driver of global warming. Other technology like direct-air capture or CO2 separation have proven to be comparatively ineffective and far exceed the costs of just planting more trees.

In their study titled The Global Tree Restoration Potential, Crowther Lab determined our planet could support 4.4 billion hectares of continuous tree coverage. With current global tree coverage sitting around 2.8 billion hectares, that means Earth could sustain 1.6 billion more hectares of forest. 

Of those 1.6 billion hectares, Crowther Lab discovered just under a billion hectares, excluding land occupied by agriculture and cities (about 1 trillion trees worth), inherently suitable for supporting reforestation efforts - that’s a land area almost the size of China.

Researchers created a map that is the “first ever quantitative, spatially explicit map of the Earth’s tree carrying capacity.” They mapped global tree coverage (among many other metrics) and, most importantly, were able to pinpoint where planting trees would not only be feasible but the most beneficial to tackling “the problem of atmospheric carbon.”

map of current global tree coverage

B: Current global tree coverage.

Map of potential global tree coverage

A: Potential global tree coverage.

The study used 80,000 high-resolution satellite images from Google Earth, artificial intelligence, and key factors such as regional soil quality, topography, and climate zones to arrive at these conclusions.

The UN Intergovernmental Panel on Climate Change (IPCC) suggested in the past that one billion hectares of reforestation would be required to make an impact on global carbon emissions and put a halt to global warming. This study proves those numbers are indeed achievable. Planting a billion hectares worth of trees could reduce the 30+ billion tonnes of excess carbon in our atmosphere by two-thirds - levels not observed since industrialization began in the mid-1800s!

The results of the study also came to some surprising conclusions that make the prospect of planting a trillion more trees much more feasible, in particular when it comes to where those trees should be planted.

list of top 10 countries for continuous tree restoration potential

Not Just a Tropical Problem

To date, most of the world’s efforts to put an end to deforestation have largely focused on tropical regions such as the Amazon, the Congo basin, and the tropical forests spread out across Southern Asia, and with good reason. Tropical forests have the ability to store massive amounts of carbon.

These forests are critical to the fight against climate change. Unfortunately, these regions have also experienced the lion’s share of global deforestation due to the resources they provide and the need for productive agricultural land to feed a growing global population. Despite their significance, they continue to be degraded.

While stopping tropical deforestation is necessary, Crowther Lab uncovered that the areas where massive reforestation could be most effective are outside of these heavily degraded regions. In fact, more than half of the 1 billion hectares of forest could be planted in the Northern Hemisphere alone, with trees going in the ground across Canada, the United States, Russia, China, and Europe. 

This means that some of the world’s largest countries and regions, in terms of both landmass and economy, hold the power to reduce half of all excess carbon emissions in the Earth’s atmosphere. That’s good news!

So, what’s the catch? 

With all that positivity, however, there are a few caveats - but they can be fixed.

For one, the researchers discovered that country-level reforestation efforts have to work out a few kinks. 

Referring to the Bonn Challenge, an initiative of 48 countries to restore 150 million hectares of forest by 2020, the researchers noted that almost half of the countries involved are only restoring 50% of the area suitable for reforestation. What's more, 10% of them have committed to restore well above what is possible, setting themselves up for certain failure and potentially causing harm to other ecosystems.

Secondly, mother nature also has a few things to say about planting that many trees. Not only would a global reforestation effort of this magnitude take considerable time to get all those trees planted, but the trees themselves need decades to grow before they can store carbon in the quantities required to impact the Earth’s climate.

All of this only adds to the urgency of the situation.

close up of an oak tree sapling

The Best Part

Despite these challenges, planting a trillion trees is totally possible. Reforestation remains the most affordable action that can be taken to combat climate change - and the easiest for everyone to get involved. 

Planting trees is cheap, simple, and requires little to no government action. Anyone can participate in global reforestation, and there are so many ways to help out.

Plant a tree yourself!  Look for places you can plant trees in your community, or even in your own garden. It’s relatively inexpensive and, best of all, it’s fun! 

One Tree Planted plans community planting events around the world during planting season, so stayed tuned for events happening near you. If there isn’t an event happening in your community, reach out to your local watershed or conservation organization to find out how you can get involved. They are always looking for volunteers to help them clean up parks and plant trees.

Support reforestation organizations.There are plenty of organizations who are taking action against climate change both at home and abroad. Support them with donations, or help them raise awareness of their cause. Here are the projects One Tree Planted is currently working on. Pick one (or two) and support us any way you can - one dollar plants one tree!

Be a conscious consumer.Knowing how your food, clothes, and all your other consumer goods are produced can make a major impact on deforestation. Aim to buy products from companies focused on sustainable practices whenever possible, and invest your money wisely. Voting with your wallet is a powerful way to affect real change.

presentation slide of 3 ways to support global reforestation

Help the World Plant 1 Trillion Trees!

We've known all along that planting trees is an effective, sustainable, simple, and fun way to give back to the environment. With the release of this study, we now have more science than ever to prove it.

Crowther Lab’s research has given the environmental community more evidence to show that planting trees and protecting our forests is more important than ever. This study has made it impossible to deny the healing power that forests and trees have for our planet.

While planting 1 trillion trees may not be entirely possible for us to do all on our own, with your support we could definitely make a massive impact together. Our projects are planting trees in some of the most environmentally significant areas, and their impact goes well beyond just helping mitigate climate change.

Check out our planting projects and learn more about how planting trees can help rebuild entire ecosystems, provide clean drinking water, create valuable job opportunities, and so much more!


We plant trees on 4 continents around the world. Want to choose where yours are planted?

by Joseph Coppolino

Organic Content Creator & Enviro-fabulist



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