Seven things to know about El Niño


While El Niño may be one of the few bright spots in forecasting future states of the atmosphere and their impacts on societal activities, there will still be some misses.

But scientists are increasingly developing a more complete understanding of this important natural phenomenon, which will surely enable governments and people worldwide to prepare for the weather associated with El Niño events.

  1. El Niño does not represent unusual behavior of the global climate.
    El Niño is a normal part of the climate system and not apart from it. El Niño (a warm event), like its counterpart La Niña (a cold event), is an integral part of the global climate system. Indeed, to go through a decade or two without an El Niño would be truly unusual.
  2. El Niño is part of a cycle.
    El Niño gets all of the attention from the media and researchers. But, extreme weather also has been associated with La Niña. Scientists say that La Niña-related extreme events are the opposite of those caused by or related to El Niño; for example, drought usually accompanies El Niño in Southern Africa, while flooding is associated with La Niña.
  3. Every weather anomaly in the world that occurs during an El Niño year is not caused by that El Niño.
    To blame just about everything that happens during an El Niño event on that particular El Niño is just plain wrong.
    El Niño has a positive side too.
    For example, during an El Niño, the number of hurricanes along the Atlantic and Gulf coasts are greatly reduced in number. Also, during an El Niño year there is a sharp increase off the coast of Ecuador in the amount of wild shrimp larvae, which is good for that country's shrimp industry.
  4. There will continue to be surprises associated with future El Niño events.
    Scientists have focused on El Niño events as Pacific basin-wide phenomena only since the mid 1970s. We have not yet witnessed all of the ways that they can affect societies and ecosystems.
  5. The impact of global warming on El Niño is not as yet known, speculation notwithstanding.
  6. Forecasting El Niño differs from forecasting the impacts of El Niño.
    The success (or failure) to forecast El Niño several months in advance of its onset is different from forecasting the impacts of that particular El Niño. Each El Niño seems to cause a different set of impacts (such as droughts, floods, fires). However, in some places, the changes in weather related to an El Niño tend to recur.

Michael Glantz, senior scientist at the National Center for Atmospheric Research and Penn alum (MTE'61, G'63, GR'70), spoke last week as part of the Alumni Lecture Series for the School of Arts and Sciences and the School of Engineering and Applied Science. He is the author of the only paperback book on El Niño, "Currents of Change: El Niño's Impact on Climate and Society."

Originally published on February 12, 1998