Trees could sink two-thirds of human-generated carbon
A worldwide effort to restore trees would be the single biggest and cheapest way to pull carbon out of the atmosphere. Researchers have found that there is 1.7 billion hectares of treeless land on which 1.2 trillion trees could grow without sacrificing crop land or urban areas. In 50–100 years, those trees would remove 200 billion tonnes of carbon — two-thirds of all emissions from human activities so far. But every year, we are pumping out tens of millions of tonnes more carbon, so new trees are just part of a solution that must also include slashing greenhouse-gas emissions (and protecting the trees we’ve already got). Research shows a trillion trees could be planted to capture huge amount of carbon dioxide
Photo: Redwood trees in Guerneville, California. Photograph: Gabrielle Lurie/The Guardian
Planting billions of trees across the world is by far the biggest and cheapest way to tackle the climate crisis, according to scientists, who have made the first calculation of how many more trees could be planted without encroaching on crop land or urban areas.
As trees grow, they absorb and store the carbon dioxide emissions that are driving global heating. New research estimates that a worldwide planting programme could remove two-thirds of all the emissions that have been pumped into the atmosphere by human activities, a figure the scientists describe as “mind-blowing”.
The analysis found there are 1.7bn hectares of treeless land on which 1.2tn native tree saplings would naturally grow. That area is about 11% of all land and equivalent to the size of the US and China combined. Tropical areas could have 100% tree cover, while others would be more sparsely covered, meaning that on average about half the area would be under tree canopy.
The scientists specifically excluded all fields used to grow crops and urban areas from their analysis. But they did include grazing land, on which the researchers say a few trees can also benefit sheep and cattle.
“This new quantitative evaluation shows forest restoration isn’t just one of our climate change solutions, it is overwhelmingly the top one,” said Prof Tom Crowther at the Swiss university ETH Zürich, who led the research. “What blows my mind is the scale. I thought restoration would be in the top 10, but it is overwhelmingly more powerful than all of the other climate change solutions proposed.”
Crowther emphasised that it remains vital to reverse the current trends of rising greenhouse gas emissions from fossil fuel burning and forest destruction, and bring them down to zero. He said this is needed to stop the climate crisis becoming even worse and because the forest restoration envisaged would take 50-100 years to have its full effect of removing 200bn tonnes of carbon.
But tree planting is “a climate change solution that doesn’t require President Trump to immediately start believing in climate change, or scientists to come up with technological solutions to draw carbon dioxide out of the atmosphere”, Crowther said. “It is available now, it is the cheapest one possible and every one of us can get involved.”
Everyone could make a tangible impact by growing trees themselves, donating to forest restoration organisations and avoiding irresponsible companies. Jean-François Bastin, also at ETH Zürich, said action was urgently required: “Governments must now factor, tree restoration into their national strategies.”
source: The Guardian, july 2019