Now it's La Nina's turn

0 Comments | Insight on the News, August 31, 1998 | by Jason Keyser

Having tracked the global effect of El Nino, scientists are sounding the alarm about another weather pattern that could have still mere devastating consequences.

Scientists from Switzerland to Australia are working to soften the blow of La Nina, the meteorological doppelganger of El Nino.

El Nino is a warming of sea-surface temperatures in the tropical Pacific that occurs every few years around Christmas--hence the name "the infant." This year's El Nino was the strongest ever recorded -- blamed for everything from wildfires in Indonesia to the migration of killer bees from South America into Nevada. But scientists now think the dust bowl of the 1930s may have been related to the phenomenon.

As El Nino gives way, a new anomaly will begin affecting world weather patterns this fall and into the winter. La Nina, a cooling of sea-surface temperatures in the tropical Pacific, will have nearly the opposite effects of the departing El Nino.

"In Indonesia, you will have wet conditions rather than the droughts you had with El Nino," says Ed O'Lenic, a meteorologist with the National Weather Service's Climate Prediction Center in Camp Springs, Md. Scientists are coordinating a system of early-warning forecasts with local emergency response. Worldwide efforts to handle El Nino paid off, and improvements in forecasting are expected to lead to lessened impacts in the future.

"People have had their consciousness raised," says Bob Livzey, a meteorologist with the Climate Prediction Center. "The evidence is overwhelming that these kinds of warnings led to mitigation efforts that reduced losses. In some cases, El Nino information led to economic gains for business communities."

The Climate Prediction Center is developing global models to display both oceanic and atmospheric data that will help forecasters warn local planners of the effects during future El Nino and La Nina occurrences. The response to these weather anomalies has to be international, says Antonio Moura, director of the International Research Institute for Climate Prediction, or IRI, established last: year at Columbia University in New York to develop forecasts and a system for warning communities worldwide.

The IRI is conducting training programs with medical communities in the tropics, from Colombia to Mali, to handle disease problems linked with El Nino and La Nina weather changes. Typical El Nino weather, which increases precipitation and temperature in parts of the tropics, accelerates the growth of disease-carrying mosquito populations.

Plagues followed this year's El Nino-driven dry-season flooding across East Africa. As a result, cholera and malaria claimed record numbers of victims across Kenya, Tanzania, Uganda and Somalia. And an outbreak of Rift Valley fever, a cattle disease that decimated herds across eastern Kenya and southern Somalia, jumped the species barrier to kill hundreds of humans.

Meteorologists say it is unusual for a La Nina to follow an El Nino. Agriculturally sensitive areas such as Indonesia, northeastern Brazil and eastern Australia, which suffered drought during El Nino, likely will have more rain. "Most areas in the tropics are looking at a better situation" says Livzey. But Chile, which had extensive flooding, faces crop-damaging drought. Florida, which had a wet winter, should be prepared for more wildfires as La Nina dries the gulf coast this winter.

Other researchers have suggested there is a relationship between alleged global warming and the rising number of El Ninos. "One theory suggests the occurrence of El Ninos are a response to help the planet adjust to mean annual temperature increases" says Livzey. "Some think El Nino may be an adjustment mechanism to help distribute the warming. There are periods in the past where El Nino has matched increases in temperature."