Stop building a spaceship to Mars and just plant some damn trees

This
story
was originally published by Mother Jones and is reproduced
here as part of the Climate
Desk
collaboration.

When it comes to climate change research, most studies bear bad
news regarding the looming, very real threat of a warming planet
and the resulting devastation that it will bring upon the Earth.
But a
new study
, out Thursday in the journal Science, offers a sliver
of hope for the world: A group of researchers based in Switzerland,
Italy, and France found that expanding forests, which sequester
carbon dioxide from the atmosphere, could seriously make up for
humans’ toxic carbon emissions.

In 2018, the United Nations’ Intergovernmental Panel on
Climate Change, the world’s foremost authority on climate,
estimated that we’d need to plant 1 billion hectares of forest by
2050 to keep the globe from warming a full 1.5 degrees Celsius over
pre-industrial levels. (One hectare is about twice the size of a
football field.) Not only is that “undoubtedly achievable,”
according to the study’s authors, but global tree restoration is
“our most effective climate change solution to date.”

In fact, there’s space on the planet for an extra 900 million
hectares of canopy cover, the researchers found, which translates
to storage for a whopping 205 gigatons of carbon. To put that in
perspective, humans emit about 10 gigatons of carbon from burning
fossil fuels every year, according to Richard Houghton, a senior
scientist at the Woods Hole
Research Center
, who was not involved with the study. And
overall, there are now about 850 gigatons of carbon in the
atmosphere; a tree-planting effort on that scale could, in theory,
cut carbon by about 25 percent,
according to
the authors.

In addition to that, Houghton says, trees are relatively cheap
carbon consumers. As he put it, “There are technologies people
are working on to take carbon dioxide out of the air. And trees do
it — for nothing.”

To make this bold prediction, the researchers identified what
tree cover looks like in nearly 80,000 half-hectare plots in
existing forests. They then used that data to map how much canopy
cover would be possible in other regions — excluding urban or
agricultural land — depending on the area’s topography,
climate, precipitation levels, and other environmental variables.
The result revealed where trees might grow outside of existing
forests.

“We know a single tree can capture a lot of carbon. What we
don’t know is how many trees the planet can support,” says
Jean-François Bastin, an ecologist and postdoc at ETH-Zürich, a
university in Zürich, Switzerland, and the study’s lead author,
adding, “This gives us an idea.”

They found that all that tree-planting potential isn’t spaced
evenly across the globe. Six countries, in fact, hold more than
half of the world’s area for potential tree restoration (in this
order): Russia, the United States, Canada, Australia, Brazil, and
China. The United States alone has room for more than 100 million
hectares of additional tree cover — greater than the size of
Texas.

The study, however, has its limitations. For one, a global
tree-planting effort is somewhat impractical. As the authors write,
“it remains unclear what proportion of this land is public or
privately owned, and so we cannot identify how much land is truly
available for restoration.” Rob Jackson, who chairs the Earth
System Science Department and Global Carbon Project at Stanford
University and was not involved with the study, agrees that forest
management plays an important role in the fight against climate
change, but says the paper’s finding that humans could reduce
atmospheric carbon by 25 percent by planting trees seemed
“unrealistic,” and wondered what kinds of trees would be most
effective or how forest restoration may disrupt agriculture.

“Forests and soils are the cheapest and fastest way to remove
carbon from the atmosphere — lots of really good opportunities
there,” he said. “I get uneasy when we start talking about
managing billions of extra acres of land, with one goal in mind: to
store carbon.” Bastin, though, says the study is “about
respecting the natural ecosystem,” and not simply planting “100
percent tree cover.” He also clarified that planting trees alone
cannot fix climate change. The problem is “related to the way we
are living on the planet,” he says.

Caveats aside, Houghton sees the study as a useful exercise in
what’s possible. “[The study] is setting the limits,” says
Houghton. “It’s not telling us at all how to implement it. That
what our leaders have to think about.”

This story was originally published by Grist with the headline
Stop building a spaceship to Mars and just plant some damn
trees
on Jul 5, 2019.

Source: FS – All – Science – News
Stop building a spaceship to Mars and just plant some damn trees