EL – NINO

Why in news?

Last year was the second or third warmest on record behind 2016, and the hottest without an extra dose of heat caused by an El Niño event in the Pacific Ocean said the United Nations (UN).

FACTS FOR PRELIMS

EL NINO

El Niño is the name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru.

When this warming occurs the usual upwelling of cold, nutrient rich deep ocean water is significantly reduced.

El Niño normally occurs around Christmas and usually lasts for a few weeks to a few months.

Sometimes an extremely warm event can develop that lasts for much longer time periods. In the 1990s, strong El Niños developed in 1991 and lasted until 1995, and from fall 1997 to spring 1998.

In an El Niño year, air pressure drops over large areas of the central Pacific and along the coast of South America.

The normal low pressure system is replaced by a weak high in the western Pacific (the southern oscillation). This change in pressure pattern causes the trade winds to be reduced == Weak Walker Cell. Sometimes Walker Cell might even get reversed.

This reduction allows the equatorial counter current (current along doldrums) to accumulate warm ocean water along the coastlines of Peru and Ecuador.

EFFECTS

The warmer waters had a devastating effect on marine life existing off the coast of Peru and Ecuador.

Fish catches off the coast of South America were lower than in the normal year (Because there is no upwelling).

Severe droughts occur in Australia, Indonesia, India and southern Africa.

Heavy rains in California, Ecuador, and the Gulf of Mexico.

SOURCE – THE HINDU.