Planting More Trees Could Cut Carbon by 25%

Scientists now know where to start restoring the forests to soak up carbon and cool the planet, by planting more trees on unused land.

Swiss scientists have identified an area roughly the size of the United States that could be newly shaded by planting more trees.  If the world’s nations then protected these 9 million square kilometers of canopy over unused land, the new global forest could in theory soak up enough carbon to reduce atmospheric greenhouse gas by an estimated 25%.

That is, the extent of new tree canopy would be enough to take the main driver of global heating back to conditions on Earth a century ago.

And a second study, released in the same week, identifies 100 million hectares of degraded or destroyed tropical forest in 15 countries where restoration could start right now – and 87% of these hectares are in biodiversity hotspots that hold high concentrations of species found nowhere else.

The global study of the space available for tree canopy is published in the journal Science.  Researchers looked for land not used for agriculture or developed for human settlement.  They excluded wetlands and grasslands already fulfilling important ecological functions.

Huge canopy increase
They left existing forests out of their calculations.  And they identified enough degraded, wasted, or simply unused land to provide another 0.9 billion hectares – that is, 9 million square kilometers – of tree canopy.

Such new or restored forest could store 205 billion tonnes of carbon.  This is about two-thirds of the 300 billion tonnes of extra carbon humans have pumped into the atmosphere since the start of the Industrial Revolution 200 years ago.

“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,” said Tom Crowther of the Swiss Federal Institute of Technology, now known as ETH Zurich.

“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.”

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