SOUTH AMERICA:
La Niña and Climate
Chaos
By Daniela Estrada*
SANTIAGO, (Tierramérica)
- It is still difficult
to predict the local
impacts of the cyclic
climate phenomenon known
as La Niña, which has
been responsible for
catastrophic floods in
Bolivia, Ecuador, Peru
and Argentina, and -- on
the other extreme --
severe drought in Chile.
The death toll has
already reached about
100, and around one
million people have been
affected by recent
floods and drought.
"La Niña" and "El Niño"
are the extreme phases
of the
oceanic-atmospheric
phenomenon known as "El
Niño-Southern
Oscillation" (ENSO),
which takes place in the
equatorial region of the
Pacific Ocean every two
to seven years,
affecting many regions
around the world to
varying degrees.
La Niña is characterized
by an atypical cooling
of the surface waters of
the ocean and an
increase in the winds
blowing east to west at
the equator. The better
known El Niño is the
opposite: warmer surface
waters and weaker winds.
La Niña tends to provoke
intense rains in
Colombia, Ecuador, the
high plains of Bolivia
and Peru and
northwestern Argentina,
and drought in Uruguay,
southern Brazil,
northeastern Argentina
and central Chile.
According to Jorge
Carrasco, chief of
Chile's weather and
climate department at
the government's
Meteorological
Directorate, the current
La Niña episode began in
May-June 2007 and is
expected to conclude
between June and August
2008, marking the
beginning of a neutral
period.
To predict the ENSO
behaviour, experts use
historical data and
dynamic and statistical
climate models generated
at centres in the United
States, Europe and Asia,
which have great
computing capacity,
Carrasco told
Tierramérica.
The information
generated by those
centres is available to
everyone over the
Internet.
"Nearly all the
countries (of South
America) have quite
broad knowledge of the
rainfall patterns
associated with the
presence of El Niño and
La Niña in their own
territories, especially
Peru, Ecuador and
Colombia," said the
expert.
Nevertheless, "one must
keep in mind that the
interaction of the
atmosphere with the
ocean is not linear, and
that means that one El
Niño or La Niña event is
never identical to
another," Rosa
Compagnucci, professor
of natural sciences at
the University of Buenos
Aires, told Tierramérica.
"Although we can predict
in advance and with some
certainty the occurrence
of an event -- and in
some cases even its
potential intensity --
it is more difficult to
predict its local
impact," added the
atmosphere and ocean
expert.
The La Niña now under
way has been an atypical
manifestation in Chile.
Experts say there should
have been heavier
rainfall in the central
region of Araucanía
during the southern
hemisphere summer
months, but it never
came. Across the
country, 144
municipalities have
declared agricultural
emergencies from the
effects of the drought.
In Bolivia, La Niña has
also surprised
meteorologists because
instead of hitting the
high plains -- in the
western provinces of La
Paz, Potosí and Oruro --
it has affected the
entire country, but
especially Pando, in the
north, and Beni and
Santa Cruz in the east,
which had already
suffered heavy floods a
year ago caused by rains
from El Niño.
"This is the first time
we've conducted a more
exhaustive monitoring of
La Niña, because about
the previous ones our
information was quite
general," said Gualberto
Carrasco, head of the
climate unit at
Bolivia's national
weather and hydrology
service, known by its
Spanish acronym SENAMHI.
"In the short term it's
important to strengthen
the early warning
system," said the expert
from SENAHMI, which is
part of the Ministry of
Sustainable Development
and Planning.
"One of the difficulties
Argentina faces is that
the official forecasting
agency, the National
Meteorological Service,
has dramatically reduced
its scientific staff. If
more meteorologists are
trained there would be
greater awareness of
these events of great
socioeconomic impact,"
said professor
Compagnucci.
Chilean expert Jorge
Carrasco says the
information produced by
his country's
Meteorological
Directorate is presented
to the relevant
authorities on a regular
basis, but he
acknowledges that a
greater effort could be
made to provide basic
information to the
population about
forecasts for droughts
or floods to improve
disaster prevention.
"There is sufficient
information in terms of
diagnosis and prediction
(of the ENSO episodes).
The models are not 100
percent correct, but in
general they have a good
record three months out.
As a result, there are
data available for
making decisions both at
the governmental and
personal levels," he
said.
Meteorology professor at
the University of Chile,
Patricio Aceituno, added
that "now under
discussion is how to
prepare programmes" to
adapt to and to mitigate
climate change caused by
human activities. "These
programmes should be
inserted into permanent
plans for mitigation and
management of extreme
climate situations, like
drought and floods," he
told Tierramérica.
"There is still great
uncertainty about the
changes that are going
to occur in the next 50
years (due to global
warming), but I would
bet, with 100 percent
certainty, that in the
next 10 years there will
be a major drought or
flood," he said.
The Chilean experts
point out that another
phenomenon acts upon
ENSO: the Pacific
Decadal Oscillation (PDO),
which manifests itself
over decades and is
believed to determine
the frequency of La Niña
and El Niño.
Studies indicate that
the positive phase of
the PDO, which has been
taking place since the
mid-1970s, is coming to
an end. It is expected
to begin its negative
phase, in which La Niña
will become more
frequent than El Niño.
But other lines of
research suggest that
beginning in 2008, "when
the new cycle begins of
the approximately 11
years of solar activity,
the probability of an El
Niño occurrence is on
the rise, reaching
maximum probability in
2012, the year,
according to predictions
of (the U.S. space
agency) NASA, expected
to have maximum solar
activity," said
Compagnucci.
(*With additional
reporting by Marcela
Valente in Argentina and
Bernarda Claure in
Bolivia. Originally
published by Latin
American newspapers that
are part of the
Tierramérica network.
Tierramérica is a
specialised news service
produced by IPS with the
backing of the United
Nations Development
Programme and the United
Nations Environment
Programme.) |
