Planting more than 500 billion trees could remove around 25 per cent of existing carbon from the atmosphere, a new study has found. What’s more: there’s enough space to do it.
Planting Billions of Trees Is The Best Climate Change Solution
The study, published in Science Friday, set out to assess how much new forest the earth could support without encroaching on farmland or urban areas and came up with a figure of 0.9 billion hectares, an area roughly the size of the U.S., BBC News reported. That makes reforestation “the most effective solution” for mitigating the climate crisis, the researchers concluded.
We must plant more trees🌲🌳, support restoration organisations and invest wisely.
— Crowther Lab (@CrowtherLab) 4 July 2019
“Our study shows clearly that forest restoration is the best climate change solution available today and it provides hard evidence to justify the investment,” senior study author and ETH-ZürichProfessor Tom Crowther said, as BBC News reported. “If we act now, this could cut carbon dioxide in the atmosphere by up to 25 per cent, to levels last seen almost a century ago.”
The new trees would remove around 200 gigatonnes of carbon, or two-thirds of what humans have pumped into the atmosphere since the industrial revolution.
Reducing Greenhouse Gas Emission along with Planting Billions of Trees
The researchers emphasized that tree planting was not a replacement for reducing greenhouse gas emissions or phasing out the use of fossil fuels.
“None of this works without emissions cuts,” Crowther told Time.
How Long will it Take?
Even if tree planting began today, it would take 50 to 100 years for the new trees to soak up those 200 gigatonnes of carbon, he told The Guardian. And, as National Geographic pointed out, the researchers found that potential tree-planting land could shrink by one-fifth by 2050 even if global temperature rise is limited to 1.5 degrees Celsius above pre-industrial levels, as some tropical areas could grow too hot to support forests.
Even so, Crowther said tree planting was an important means of immediate climate action.
It’s “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 told The Guardian. “It is available now, it is the cheapest one possible and every one of us can get involved.”
Assistant-Director General at the UN Food and Agriculture Organization René Castro praised the study’s utility.
“We now have definitive evidence of the potential land area for re-growing forests, where they could exist and how much carbon they could store,” Castro said, as The Guardian reported.
What was the Research Methodology?
The researchers first looked at around 80,000 satellite photographs of protected forest areas around the world to assess the tree cover in each. They then used Google Earth Engine mapping software to develop a model for predicting where new trees could grow, National Geographic explained. They found that more than half of the world’s reforestation potential was located in six countries: China, the U.S., Russia, Australia, Canada and Brazil.
However, trends are moving in the opposite direction in Brazil, where deforestation is on the rise under the right-wing government of President Jair Bolsonaro. Recent satellite images show that a football-field-sized swath of the Amazon is being lost every minute, according to National Geographic.
Political realities are why some scientists criticized the optimism of Crowther’s findings.
“Planting trees to soak up two-thirds of the entire anthropogenic carbon burden to date sounds too good to be true. Probably because it is,” University of Reading professor Martin Lukac told BBC News. “This far, humans have enhanced forest cover on a large scale only by shrinking their population size (Russia), increasing the productivity of industrial agriculture (the West) or by direct order of an autocratic government (China). None of these activities looks remotely feasible or sustainable on a global scale.”
University College London professor Simon Lewis, meanwhile, said that the amount of carbon the study said trees would absorb was too high. He said the study had not accounted for the carbon already in the soil before trees were planted or the hundreds of years it would take for the trees to achieve their full storage potential, The Guardian reported.
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