El Nino
While some forecasting methods had limited
success predicting the 1997 El Nino a few months in advance, the Columbia
University researchers say their method can predict large El Sino events up to
two years in advance. That would be good news for governments, farmers and
others seeking to plan for the droughts and heavy rainfall that El Nino can
produce in various parts of the world.
Using a computer, the
researchers matched sea-surface temperatures to later El Nino occurrences
between 1980 and 2000 and were then able to anticipate El Nino events dating
back to 1857, using prior sea-surface temperatures. The results were reported in
the latest issue of the journal Nature.
The researchers say
their method is not perfect, but Bryan C. Weare, a meteorologist at the
University of California, Davis, who was not involved in the work, said it
"suggests El Nino is indeed predictable."
"This will probably
convince others to search around more for even better methods," said Weare. He
added that the new method "makes it possible to predict El Nino at long lead
timess." Other models also use sea-surface temperatures, but they have not
looked as far back because they need other data, which is only available for
recent decades, Weare said.
The ability to predict the warming
and cooling of the Pacific is of immense importance4. The 1997 El Nino, for
example, caused an estimated $20 billion in damage worldwide, offset by
beneficial effects in other areas, said David Anderson, of the European Centre
for Medium-Range Weather Forecasts in Reading, England. The 1877 El Nino,
meanwhile, coincided with a failure of the Indian monsoon and a famine that
killed perhaps 40 million in India and China, prompting the development of
seasonal forecasting, Anderson said.
When El Nino hit in 1991
and 1997, 200 million people were affected by flooding in China alone, according
to a 2002 United Nations report.
While predicting smaller El
Nino events remains tricky, the ability to predict larger ones should be
increased to at least a year ff the new method is confirmed.
El
Nino tends to develop between April and June and reaches its peak between
December and February. The warming tends to last between 9 and 12 months and
occurs every two to seven years.
The new forecasting method does
not predict any major El Nino events in the next two years, although a weak
warming toward the end of this year is possible. |
