Science, Tech & Environment

The Pacific Ocean is gearing up for a big El Niño

El-Nino-dust storm.jpg

A dust cloud descends on Melbourne on February 8, 1983, a super El Niño year.

Credit:

Trevor Farrar/Australia Bureau of Meteorology

Researchers say conditions in the Pacific Ocean could generate a powerful El Niño this year. If El Niño returns, it could intensify droughts and storms around the world. Just what the global climate needed, right?

Player utilities

Listen to the Story.

El Niño — and its sibling La Niña — entered the American vernacular in 1998. That year, the strongest El Niño ever measured disturbed weather patterns across the world, creating the hottest year on record, killing an estimated 2100 people and causing close to $33 billion in property damage, according to National Geographic.

In other words, predictions for a major El Niño in 2014-2015 are not to be taken lightly.

El Niño may be loosely defined as a build-up of unusually warm surface waters in the central and eastern equatorial Pacific Ocean that leads to global changes in temperature, wind patterns and precipitation. Kevin Trenberth, a distinguished senior scientist in the climate analysis section at the National Center for Atmospheric Research, is monitoring conditions in the Pacific. He describes the phenomenon this way:

“El Niños occur about every three to seven years. In between these events, trade winds blow across the Pacific from the east, creating a build-up of warm water in the western Pacific. After a period of time, the ocean says, ‘There’s too much warm water piling up here over by Indonesia, and I’m going to have an El Niño event.’ Some of this warm water starts to spread back across the Pacific, and the winds change as that happens [i.e. begin blowing from west to east]. Once it gets rolling, it continues for nine months to a year.”

Trenberth says there are several reasons to suspect we are in the beginning stages of El Niño. First, he says, this is the right time of year for the transition to begin.

“The main time when El Niño tends to get started is March, April, May,” he says, “so this is certainly the time to watch. The second thing is that there has been a quick reversal of the normal easterly trade winds to brief westerly wind bursts.”

In addition, Trenberth says, scientists already see warming in the upper layer of the ocean, with some of the “temperature anomalies” reaching eight degrees Fahrenheit above normal. The last time scientists saw these kinds of numbers, he says, was in 1997-1998, during the last big El Niño event. If El Niño develops in 2014-2015, it will likely lead to a repeat of the disastrous weather the world experienced then.

In the US, Trenberth says, there are greater odds of storms “barreling into southern California.” Some of these storms would continue across the south, even to Florida. At the same time, the northern plains states could expect warmer and somewhat dryer conditions, while the Northeast and Canada could see a reapearance of the severe ice storms that devastated much of those regions.

In other parts of the world, there will be trouble as well. El Niño greatly increases the risk of drought in Australia, which has already had its warmest year on record; increases the risk of wildfire in southeast Asia and Indonesia; would likely cause deluges and flooding in Peru and Ecuador and could lead to severe drought across parts of Africa.

Because of climate change, Trenberth says, the floods and droughts that occur will likely be stronger than they otherwise would be.

The 1997-98 El Niño marked the first time that climate scientists were able to predict abnormal flooding and droughts months in advance. Trenberth says the technology we have today enables scientists to give the world plenty of notice if El Niño blossoms as expected. At the very least, Trenberth says, “we’re almost guaranteed that this next year will be rather different than the last three or four we’ve had.”

This story was first published as part of PRI's Living on Earth, a weekly radio show on science and the environment. 

  • El nino water wind NASA.jpg

    The image shows what happens when a very strong El Nino strikes surface waters in the Central equatorial Pacific Ocean. The sequence shows warm water anomalies (red) develop in the Central Pacific Ocean. Winds that normally blow in a westerly direction weaken allowing the easterly winds to push the warm water up against the South American Coast.

    Credit:

    NASA

  • La Nina wind and waters.jpg

    This image shows colder than normal water (blue) anomalies in the central equatorial Pacific associated with La Nina. Stronger than normal trade winds bring cold water up to the surface of the ocean.

    Credit:

    NASA