Does planting trees actually cool the planet? - Carolyn Beans
In the fight to curb climate change,
there are few solutions more discussed
than planting lots and lots of trees.
It sounds simple enough— trees absorb
CO2 from the atmosphere to grow,
so planting more of them should help
eliminate greenhouse gases.
The trouble is, tree planting efforts
don't always work as planned.
For example, between 1974 and 2012,
the Chilean government helped
fund the planting
of over a million hectares of new trees.
Yet a recent analysis suggests
this multi-million dollar effort
resulted in no major carbon storage gains.
What went wrong?
Chile focused on afforestation:
the planting of trees in places long
devoid of— or never home to— any forest,
as opposed to reforestation,
the practice of restoring recently
degraded forests.
Many governments and international
organizations champion afforestation
in their efforts to meet
lofty tree planting goals
that require massive amounts of land.
The Bonn Challenge, launched in 2011
by the German government
and the International Union
for Conservation of Nature,
aims to restore 350 million hectares
of degraded land
across the globe by 2030,
in part through afforestation.
Many companies have also seized
on tree planting to offset emissions
and, in some cases, negative PR from their
contributions to the climate emergency.
A 2021 Oxfam analysis found that the area
needed to match the tree planting goals
set by four of the largest
oil and gas producers
would require land twice the size
of the UK.
Here's where things get complicated.
In order to be a long-term carbon sink,
trees need to grow to maturity
and stay put.
Most of Chile's afforestation funding went
to the commercial forestry industry,
which drastically expanded plantations
of mostly non-native trees—
in some cases even by plowing
into native forests.
According to one study, on average,
natural forests are 40 times better
at carbon storage than plantations.
A mature tree can absorb up to
22 kilograms of carbon dioxide each year.
But plantation trees are harvested.
Further, pine and eucalyptus—
two commonly grown plantation trees—
are highly flammable,
so gains in carbon storage
can quickly go up in smoke.
And not all land should be forested.
In 2019, researchers estimated that,
of the 100 million hectares of land
targeted for a tree planting initiative
in Africa,
most is savanna.
Dropping trees into Africa’s savannas
threatens wildlife
that thrive in sunlight and open spaces.
And wildfires,
not to mention a passing elephant,
can quickly stomp out years
of tree growth.
Meanwhile, a savanna’s natural vegetation
tucks most of its carbon
safely away below ground,
where it’s protected
from fire and hungry herbivores.
Planting trees can also have
unintended consequences
in places that naturally reflect sunlight
like drylands or snowy terrain.
Trees in these regions could absorb
more of the Sun’s rays,
contributing to a warmer planet.
It’s not that we shouldn’t
plant more trees.
But for the best chance of success,
programs should consider which
species to plant, which lands to forest,
and how to protect the land long-term.
Today, Chile is prioritizing planting
native trees
rather than timber plantations.
Some researchers argue that a more
efficient way to re-green the planet
is to protect forests
and let nature do the work.
On recently deforested land,
seeds wait in soil and new sprouts grow
from old stumps.
As time passes, birds and winds
deliver seeds from forests nearby.
Others support programs that practice
assisted natural regeneration—
helping nature along by removing grasses
that compete with saplings,
preventing grazing,
and even planting trees in small patches.
So when is it bad to plant trees?
When programs put the wrong trees
in the wrong places.
It’s bad when it’s mistakenly used
as a catch-all solution,
rather than addressing more
complex issues like carbon emissions
and active deforestation.
It’s also bad to plant trees when it
allows companies and governments
to practice greenwashing,
throwing money at initiatives that
have no real chance of achieving
the carbon offsets they promise.
The best investments in a greener future
are to cut carbon emissions,
while protecting these forests from being
destroyed in the first place.
