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The 'Sleeping Giant' in Arctic Permafrost
presented by Science@NASA
Flying low and slow
above the pristine terrain of Alaska's North Slope
research scientist Charles Miller
of NASA's Jet Propulsion Laboratory
surveys the white expanse of tundra
and permafrost below.
On the horizon, a long, dark line appears.
His plane draws nearer,
and the mysterious object reveals itself to be a massive herd
of migrating caribou,
stretching for miles.
It's a sight Miller won't soon forget.
'Seeing those caribou
marching single-file across the tundra
puts what we're doing here in the Arctic into perspective,' says Miller,
who is on a five-year mission named 'CARVE'
to study how climate change is affecting the Arctic's carbon cycle.
CARVE is short
for the 'Carbon in Arctic Reservoirs Vulnerability Experiment.'
Now in its third year,
the airborne campaign is testing the hypothesis
that Arctic carbon reservoirs are vulnerable to warming,
while delivering the first source-maps of greenhouse gases,
carbon dioxide,
and methane.
About two dozen scientists
from 12 institutions are participating.
'The Arctic is critical to understanding global climate,'
says Miller.
'Climate change is already happening in the Arctic,
faster than its ecosystems can adapt.
Looking at the Arctic
is like looking at the canary in the coal mine
for the entire Earth system.'
Over hundreds of millennia,
Arctic permafrost soils have accumulated vast stores of organic carbon -
an estimated 1,400 to 1,850 billion metric tons of it.
That's about half of all the estimated organic carbon
stored in Earth's soils.
In comparison,
about 350 billion metric tons of carbon
have been emitted from all fossil-fuel combustion
and human activities since 1850.
Most of the Arctic's sequestered carbon
is located in thaw-vulnerable topsoils
within 3 meters of the surface.
But, as scientists are learning,
permafrost - and its stored carbon -
may not be as permanent as its name implies.
And that has them concerned.
'Permafrost soils are warming even faster than Arctic air temperatures -
as much as 1.5 to 2.5 degrees Celsius
in just the past 30 years,' says Miller.
'As heat from Earth's surface penetrates into permafrost,
it stimulates soil processes
that mobilize these organic carbon reservoirs
and release them into the atmosphere
as carbon dioxide and methane,
upsetting the Arctic's carbon balance
and greatly exacerbating global warming.'
CARVE campaign flights
are conducted aboard a specially instrumented NASA C-23 Sherpa aircraft
from NASA's Wallops Flight Facility
on Wallops Island in Virginia.
The C-23 won't win any beauty contests -
its pilots refer to it as
'a UPS truck with a bad nose job.'
Inside, it's extremely noisy -
the pilots and crew wear noise-cancelling headphones to communicate.
'When you take the headphones off,
it's like being at a NASCAR race,' Miller quipped.
But what the C-23 lacks in beauty and quiet,
it makes up for in reliability
and its ability to fly 'down in the mud.'
Most of the time,
it flies about 150 meters above ground level,
with periodic ascents to higher altitudes
to collect background data.
Onboard the plane,
sophisticated instruments sniff the atmosphere for greenhouse gases.
'[We] need to fly very close to the surface in the Arctic
to capture the interesting exchanges of carbon
taking place between Earth's surface and atmosphere,' Miller says.
The CARVE team flew test flights in 2011
and science flights in 2012.
So far in 2013
they have completed three monthly campaigns--
in April, May and June--
with four more to go.
From a base in Fairbanks, Alaska,
the C-23 flies up to eight hours a day
to sites on Alaska's North Slope,
interior and Yukon River Valley over tundra,
permafrost, boreal forests, peatlands
and wetlands.
Soaring over the Arctic terrain,
Miller has seen many things he won't forget.
Like the Caribou,
the data may prove unforgettable, too.
For more news from the ends of the Earth-and beyond-
visit science.nasa.gov.