34 | New Scientist | 5 October 2019Seeing the
woods
Trees absorb carbon and are our most
powerful ally against climate change, but we
still don’t know their full potential. That is
set to change, finds Christine Swanson
E
XCITEMENT in the room was palpable
on the morning of 5 December last year.
The day before, the launch of SpaceX’s
Falcon 9 to supply the International Space
Station had been delayed for 24 hours. That
followed the discovery on board of mouldy
food – not bound for the ISS crew but to feed
some mice set to join them. Now, a crowd had
gathered at Kennedy Space Center in Florida
for the rescheduled lift off. Stowed along with
the mice and fresh feed were experiments,
including a remote-sensing system called
GEDI – pronounced like the Jedi in Star Wars.
GEDI – the Global Ecosystem Dynamics
Investigation – turns out to be a particularly
precious cargo. It is a NASA mission designed
to provide the first three-dimensional look
at the world’s forests. Surprisingly, given
our achievements in space, we still have
only a vague idea of how much living
matter is on Earth. We do know that trees
make up the bulk of it. We also know that
forestation and deforestation contribute to
atmospheric carbon dioxide concentrations.
So, the unprecedented information that
GEDI gathers on trees will be essential for
MAunderstanding climate change.
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The SpaceX launch was just the beginning.
GEDI is in the vanguard of a new wave of
innovative sensors that will assess the
world’s plant life and how it is changing –
how much carbon, for instance, is lost to
the atmosphere when trees are destroyed
as a result of catastrophic events such as
wildfires, hurricanes and logging. These
eyes in the sky will be invaluable in efforts
to protect and regenerate forests, too. At last,
we are starting to get a holistic picture of our
green planet – and what we risk losing if we
don’t take action.
Understanding the flow of carbon between
living matter and the atmosphere is crucial
if we are to tackle global warming caused by
carbon dioxide. But tracking carbon can be
tricky. We know that CO2 emissions from
industry, vehicles and other sources put
about 10 billion tonnes of carbon into the
atmosphere each year. But not all of it stays
there. “About half of what we’re pushing up
into the atmosphere disappears back into
the land systems somewhere,” says Laura
Duncanson at the University of Maryland,
who is a member of the GEDI team. “Where
that is and the processes that govern that, this