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California Drought -
presented by Science@NASA
California is supposed to be the Golden State.
Make that golden brown.
The entire west coast of the United States
is changing color as the deepest drought
in more than a century unfolds.
According to the US Dept. of Agriculture and NOAA,
dry conditions have become extreme
across more than 62% of California's land area-
and there is little relief in sight.
'Up and down California,
from Oregon to Mexico,
it's dry as a bone,'
comments climatologst Bill Patzert
of NASA's Jet Propulsion Laboratory.
'To make matters worse,
the snowpack in the water-storing Sierras
is less than 20% of normal for this time of the year.'
'It's painful,' he says.
The drought is so bad,
NASA satellites can see it from space.
On Jan. 18th, 2014-
just one day after California governor Jerry Brown
declared a state of emergency-
NASA's Terra satellite snapped a sobering picture
of the Sierra Nevada mountain range.
Where thousands of square miles of white snowpack should have been,
there was just bare dirt and rock.
At the Jet Propulsion Lab,
a group of researchers led by Tom Painter
are preparing to fly a Twin Otter aircraft
over the Sierras to investigate the situation.
Their 'Airborne Snow Observatory'
is equipped with a laser radar and a spectrometer
to measure the snow's depth and reflectivity.
From these data,
it is possible to calculate the water content of the Sierras
within 5% and future snowmelt rates with similar precision.
'The Airborne Snow Observatory
was designed for times like this
when we really need to know the state of the snow pack,'
says Painter.
'Our next flight will be over the Tuolumne River Basin.'
The Tuolumne watershed and its Hetch Hetchy Reservoir
are the primary water supply for 2.6 million
San Francisco Bay Area residents.
The change in scenery is so striking,
a group of high school science students in central California
have been flying high altitude balloons to photograph the drought.
From the stratosphere,
their home town of Bishop looks like a settlement
on the planet Mars.
The citizen science club,
called 'Earth to Sky Calculus,'
has recorded hours of video footage in December and January
documenting the progress of the drought.
'The lack of snow is really striking,'
says club president Amelia Koske-Phillips.
'In my lifetime,
we've never had a winter as brown as this,' adds Carson Reid,
a member of the launch team.
Bill Patzert blames the drought, in part,
on the Pacific Decadal Oscillation, or 'PDO,'
a slowly oscillating pattern of sea surface temperatures
in the Pacific Ocean.
At the moment,
the PDO is in its negative phase-
a condition historically linked to extreme high-pressure ridges
that block West Coast storms
and give the Midwest and East Coast punishing winters.
'I'm often asked if this is part of global warming,' says Patzert.
'My answer is 'not yet.'
What we're experiencing now is a natural variability
that we've seen many times in the past.
Ultimately, though,
climate change could make western droughts much worse.'
For more information about climate change
and other Earth science topics,
stay tuned to Science.nasa.gov