Is drought El Nino's fault? Scientists say 'it depends' Part of problem is defining 'normal' climate

July 17, 1998|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

BOULDER, Colo. -- Scientists gathered here for a La Nina "summit" say they are being deluged with questions about the deadly heat and punishing drought that have been tormenting parts of the deep South and Southwest.

Everyone wants to know whether the hot, dry weather can be blamed on El Nino, or its newly arrived cousin, La Nina.

The answer, they say: "It depends on whom you talk to."

"My own interpretation is that this is part of the natural chaos of the climate system," said Mike McPhaden, of the National Oceanic and Atmospheric Administration. "Droughts happen."

Although people tend to think that "normal" weather is weather that stays close to a narrow range of temperatures and precipitation amounts, "normal" is a long-term average of data that includes extremes of both temperature and precipitation.

But not everyone agrees that this summer's drought and killer heat in Texas and elsewhere just happened.

"At the tail end of a warm [El Nino] event, this is just what you would expect," said James O'Brien, of Florida State University's Center for Ocean-Atmospheric Prediction Studies, in Tallahassee.

His analyses of 40 years of climatic data from 600 U.S. weather stations show that very dry weather in the northern half of Texas, in Oklahoma and Arkansas are par for the course in summer at the end of an El Nino year.

O'Brien's data are less able to explain the 100-degree-plus heat wave, which has been blamed for at least 55 deaths. His maps show no such occurrences in the wake of most El Nino events. But perhaps this El Nino was so big it broke the mold. "Maybe it's so rare we don't know all of its impacts. There may be other effects," O'Brien said.

Pub Date: 7/17/98

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