Planting Billions of Trees Is the 'Best Climate Change
Solution Available Today,' Study Finds
Olivia Rosane Jul. 05, 2019 06:51AM EST CLIMATE
Planting more than 500 billion trees could remove around 25
percent of existing carbon from the atmosphere, a new study has found. What's
more: there's enough space to do it.
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.
"Our study shows clearly that forest restoration is the
best climate change solution available today and it provides hard evidence to
justify investment," senior study author and ETH-Zürich Professor Tom
Crowther said, as BBC News reported. "If we act now, this could cut carbon
dioxide in the atmosphere by up to 25 percent, 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.
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However, 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.
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.
To reach their conclusions, 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.
Bolsonaro has also been hostile to the rights of indigenous
communities to the forest. But such rights are essential for conservation:
deforestation rates are much lower in forests that recognize indigenous claims.
"We have served as guardians of these lands for
generations ... We also understand how to restore them to health," Joan
Carling, a member of the Kankanaey tribe in the Philippines and co-convener of
the Indigenous Peoples Major Group for Sustainable Development, told National
Geographic by email. "With the security of our lands and resources, we can
prevent destructive logging, mining, agri-business, and other projects from
occurring in our territories."
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 productivity of
industrial agriculture (the West) or by direct order of an autocratic
government (China). None of these activities look remotely feasible or
sustainable at 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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