http://news.bbc.co.uk/2/hi/science/nature/2559633.stm
Tuesday, 10 December,
2002, 09:58 GMT
Bolivian glaciers shrinking fast
By Andrew Enever
BBC News Online, on the Cordillera Real mountain range, Bolivia
QUOTE:
"The bare rock around the glacier works as an oven,
speeding the melting"
Dr Robert Gallaire
CAPTION:
"Huayna Potosi: The cities below depend on the meltwaters"
Glaciers in the
Bolivian Andes are shrinking at an alarming rate,
say scientists.
Data collected from
tropical ice fields near the world's
highest capital, La Paz, show mass loss in the 1990s at rates
10 times greater than previous decades.
If rising temperatures
and low precipitation continue,
many smaller glaciers will vanish in a decade, the
researchers believe.
Further ahead, the
consequence could be water and power
shortages for millions of Bolivians.
Dangerous work
Alvaro Soruco led the
way across the Zongo glacier,
cautiously poking the ground before him in search of
deadly fissures that plummet deep into the dark heart
of this slowly moving mass of ice.
To our right, the glacier
climbed near vertically to the
towering peak of Huayna Potosi (6,050 metres/19,850 feet).
Lines could be made
out on the ice wall - fractures, Alvaro
informed me, which one day would be the starting point of an
avalanche.
All around us on the
snow were small insects, blown up in a
cloud from their tropical Amazon home and dropped on to this
white carpet to take their last confused steps. And echoing up
from far below came the distant gurgle of running water.
Data collection
Crossing this glacier
is a weekly event for Alvaro,
a 22-year-old student working with the French Institut
de Recherche pour le Developpement (IRD).
From a measuring station
located 5,200 m above sea level,
he records data showing precipitation, wind speed, air
temperature and other variables that help the team from
the IRD map the changing form of the glacier.
For a decade now, in
fair and foul weather, the team has been
collecting data on this and two other glaciers in the Cordillera
Real mountain range, which curves around La Paz and off north
towards Peru.
The results have been
alarming.
Losing mass
The Zongo glacier has
retreated by around 10 metres
and lost about one metre of depth every year.
The nearby Chalcaltaya
glacier, known as the world's
highest ski-field, has lost over 40% of its thickness
and surface area.
The key factor accelerating
mass loss on these glaciers
is increasingly frequent El Nino events in this part of
the world, a climate phenomenon that may or may not be
being pumped up by global warming.
"This is a problem
for the glaciers because it means lower
precipitation and higher temperatures," explained Dr Robert
Gallaire, head of the La Paz IRD unit.
Glaciers are shrinking
all over the planet. But tropical
glaciers, most of which are in the Andes, are losing ground
fastest.
Tropical glaciers
These low-latitude
high-altitude glaciers are particularly
sensitive to changes in climate because their season of
accumulation is summer, when radiation levels are at their
peak.
In Europe or elsewhere,
glaciers accumulate during the
cold season, allowing some recovery.
In the Andes, the run-off
goes on all year, leaving smaller
glaciers, like Chacaltaya, exposed.
"Chacaltaya no
longer has enough inertia," said Dr Gallaire.
"The bare rock around the glacier works as an oven, speeding
the melting. Even in 2000/1 when we had a strong La Nina year
with a lot of snowfall, it continued to lose mass."
Important water
source
Run-off from glaciers
in the Cordillera Real contributes
to reservoirs that supply 1.5 million people in La Paz and
the neighboring city El Alto. It also feeds a series of
hydroelectric plants that satisfy the two cities' energy
needs.
If current warming
trends continue, Dr Gallaire fears
that within 50 years the loss of glaciers will impact
heavily on these water supplies.
Robert Bianchi, general
manager at the La Paz water
company, Aguas del Illimani, is not so worried.
He insists that despite
the contribution of glacier
waters, it is rainfall that meets the majority of water
needs. Bianchi also doubts the credibility of long-term
water demand and supply estimates.
"To project the
problem of water for La Paz and El Alto
in 50 years is the work of an artist," he says. "If
it
is a problem that will affect the next generation it will
be a problem for the next concessionaire who takes over
in 2027."
Oscar Paz, who heads
up Bolivia's climate change office,
hopes the world's most powerful nations will not leave
their response to a changing climate to the next generation
of politicians.
"The most vulnerable
countries like Bolivia, who don't have
resources to face these problems, are those that will feel
the impact of climate change most strongly," he said.
"We need developed
nations to act now to control carbon
emissions, but also to support us financially as we try
to adapt."
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