If history is any guide, the activity of this year's El Nino weather
cycle could trigger severe drought in parts of Thailand and higher
temperatures throughout the country once the rainy season ends,
climate experts say.
A worldwide weather phenomenon which seems to recur every half-dozen
years or so, El Nino does not seem to have as much
impact on Thailand as some other countries in the region, notably
Indonesia and the Philippines, which are currently suffering
droughts.
But a study by the Meteorological Department's Climatology Division
concludes that El Nino does cause Thailand to experience
''above normal temperatures in the winter and summer seasons starting
from November of the [El Nino] year to May of the following
year".
El Nino's impact on rainfall in Thailand is not as clear, according
to
the researchers. A comparison of past El Nino cycles does not
reveal much consistency in rainfall patterns, making it difficult to
predict the features of this year's rainy season.
But perhaps the one consistent feature which does emerge from such a
study, is that a large swathe of the North seems to receive
less than normal rainfall while El Nino is in action. Since this is
where the reservoirs which provide Bangkok and the Central region
with much of their water supply are located, this may well lead to
a
water shortage next year.
A climatologist at the Meteorological Department agreed that this was
a reasonable assessment, but warned against jumping to
conclusions too soon. ''There are many factors to consider before
making an actual forecast," said the official, who asked not to be
named.
Following on the heels of the country's financial collapse, a drought
in the Central region Thailand's main rice-growing area
could
have severe economic consequences.
Rainfall statistics reveal that the North has indeed had a relatively
dry year so far: as of Aug 19, the Bhumibhol and Sirikit reservoirs
were only at 29 per cent and 27 per cent of capacity respectively,
according to the Royal Irrigation Department. But weather officials
remain hopeful that a storm or two may still blow in to top up
northern reservoirs before the monsoon season ends.
El Nino is a global climate phenomenon linked to a periodic
''invasion" of warm water in the southern Pacific Ocean near South
America, but which seems to affect weather patterns around the world.
In normal years, Antarctic currents along with the prevailing trade
winds cause an upwelling of nutrient-rich cold water off the coast
of
Peru. But during the El Nino cycle, which can last for 12 to 18
months, the Pacific trade winds seem to relax or even reverse,
pushing waves of warm water eastward across the ocean to replace the
cold upwelled water.
Folklore suggests that this event was originally named ''El Nino"
after the Christ Child, because a period of unseasonably warm
weather often ensues in Peru around Christmas time, but the term has
now been extended to cover the entire global phenomenon.
Weather anomalies linked to El Nino include droughts in Australia,
Indonesia, the Philippines, continental India, southeastern Africa,
northwestern South America, central America and the Caribbean, while
floods or heavy rain are often experienced in the central
Pacific, northern and eastern Africa, southern Europe and northeastern
South America, according to the Climatology Division.
''In Thailand, however, it is difficult to say what the effects of El
Nino are, because the rainfall patterns are not the same," said the
climatologist. ''On a large scale, there will be drought in the
region, but on a smaller scale, effects vary."
A look at the rainfall maps from past El Nino years reveals just how
difficult it is to make predictions for this year:
-- In the 1957-to-1958 episode there was drought in the North,
Northeast and South, but the Central region had high rainfall;
-- In the 1965 event, the Central plains, the Western provinces and
the South all received high rainfall, but the North and Northeast
were relatively dry;
-- In the 1972 event, the upper North, upper Northeast, far South and
the East all suffered from a lack of rainfall, but there was plenty
of rain in the Central, western and lower Isaan provinces;
-- The 1982-to-1983 episode saw drought in the North and parts of the
Central and southern regions, while much of the Northeast,
Central plains and upper South had good rain;
-- The 1986-to-1987 event left the North dry, but the Central region,
most of the Northeast and the South had plenty of rain;
-- And the most recent El Nino episode in 1991 also left the North
dry, along with the Central plains, but much of Isaan and the South
again had good rain.
A similar pattern has so far held this year: rainfall has been lacking
in the North and many Central and eastern provinces, but
plentiful in the West and parts of the Northeast while the South was
recently hit by severe flooding.