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Environment

El Nino is back: six questions and answers

Australia's meteorological authority has reported the onset of El Nino in the tropical Pacific. This is the first appearance of the potentially disastrous weather phenomenon in five years. DW takes a closer look.

Australia's Bureau of Meteorology said Tuesday that El Nino would pack a punch in 2015, announcing not only that the climate pattern had begun, but that it would bring forth particularly intensive weather in the Pacific this year.

"This is a proper El Nino effect; it's not a weak one," David Jones, manager of climate monitoring and prediction at the Bureau, told reporters at a media briefing.

El Nino doesn't occur every year. To help you understand more about this unique climate phenomenon, DW's environment team have answered six common questions about El Nino.

What exactly is El Nino?

El Nino is a climate anomaly in the South Pacific: In irregular intervals, the ordinary weather situation changes. The phenomenon occurs between Latin America's west coast and Southeast Asia, but its effects can be felt worldwide and it has often led to natural disasters.

Usually, warm sea surface water flows west from Latin America while cold water flows from the depths of the ocean to Latin America's coasts. In El Nino years those currents subside and sometimes change direction. The surface sea water off the coasts of Australia and Indonesia drop several degrees, whereas water temperatures in Latin America rise. The El Nino phenomenon last occurred in the years 2009 and 2010. Periods of El Nino usually last about a year.

What are the environmental impacts?

Corals, plankton and algae die in the warmer waters off Latin America's coast. Fish leave, searching for new waters due to a lack of food. This, in turn, impacts on Latin America's fishing industry.

The considerable warming of water also leads to low pressure areas off Latin America's west coast. This results in torrential rain, landslides, floods and storms. In the West Pacific – in Indonesia and northern Australia – it's the other way around: droughts, poor harvests and forest fires occur. During El Nino, the monsoon that usually brings the much-needed rain, either comes too late or doesn't come at all.

Tree stands alone in the desert

While El Nino can lead to heavy rain in Latin America, it can cause drought elsewhere

What are the causes?

Researchers still don't know exactly. But there are indications that El Nino is not man-made and instead has naturally-existed for centuries. But the greenhouse effect could be intensifying the El Nino phenomenon, so that it occurs more often or more intensely.

Where does the name El Nino come from?

The variations caused by El Nino tend to climax around the Christmas period. Peruvian fishermen, who were most affected by the climate phenomenon because of the lack of fish, dubbed it El Nino - meaning ‘the boy' in Spanish, which in capital letters refers to baby Jesus.

How permanent is the El Nino climate phenomenon?

Based on several well-established climate models, researchers from the Germany-based GEOMAR Helmholtz Center for Ocean Research have calculated that El Nino could become more common. By the year 2100, they say, typical air currents could weaken in general and shift eastwards as a result of global warming. That would lead to a permanent El Nino effect. But the researchers say it would have minimal effects.

There is also conflicting evidence. In fact, data from 1979 to 2013 actually suggests that there has been an overall intensification of air circulation, which would work against the El Nino cycle. The gloomy prediction of a permanent El Nino effect is merely based on estimates.

Gabriel Borrud contributed to this report.

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