Human-made carbon emissions could be cut by two thirds through reforestation, according to a study by the Crowther Lab of ETH Zurich. Published today in the journal Science, the study reveals this could be achieved by rolling out the game changing nature-based solution across 0.9 billion hectares of land globally.

‘Total land available that can support trees across the globe (total of current forested areas and forest cover potential available for restoration)’. Credit: Crowther Lab / ETH Zurich.

US-sized opportunity

The research identifies the suitable land for planting trees, and the accompanying carbon that could be captured. While the total amount of useable land is actually 1.6 billion hectares, it drops to 0.9 billion – roughly the size of America – due to the needs of human populations.

“One aspect was of particular importance to us as we did the calculations: we excluded cities or agricultural areas from the total restoration potential as these areas are needed for human life,” said Jean-François Bastin, study lead author and postdoc at the Crowther Lab.

‘Land available for forest restoration (excluding deserts, agricultural and urban areas; current forestland not shown)’. Credit: Crowther Lab / ETH Zurich.

Countries with biggest potential

More than 205 billion tonnes of carbon could be stored, two thirds of the 300 billion generated since the Industrial Revolution from human activity, once trees planted on the 0.9 billion hectares reached maturity.

Russia (151 million hectares); the US (103 million hectares); Canada (78.4 million hectares); Australia (58 million hectares); Brazil (49.7 million hectares); and China (40.2 million hectares) are the six countries best suited to reforestation.

“We all knew that restoring forests could play a part in tackling climate change, but we didn’t really know how big the impact would be. Our study shows clearly that forest restoration is the best climate change solution available today. But we must act quickly, as new forests will take decades to mature and achieve their full potential as a source of natural carbon storage,” added Prof. Thomas Crowther, co-author of the study and founder of the Crowther Lab at ETH Zurich.

Check out the tool on Crowther Lab’s website to discover exactly how many trees can be grown in different parts of the world – and the amount of carbon they would capture.

While you’re here, listen to our Editor-at-Large, Marc Buckley + Expert Analyst, Dr Rocio Ortego, talk about planting a trillion trees with a young representative from the Plant-for-the-Planet initiative. The interview took place at last year’s COP24 in Poland.