Introduction

No work on climate and variability is worth its grain of salt unless it explores the influence of the El Niño/La Niña phenomena on that countrys climate. These events are both a normal part of the earth‘s climate and there are recorded evidence of them having occurred for hundreds of years.

The term El Niño (Spanish for "the boy" referring to the Christ child) originally designated as a warm southward current which appeared every few years around Christmas off the coast of Ecuador and Peru, flowing above the cold waters that normally bathe this barren coast.

At first it was viewed as an Eastern Pacific phenomenon. In the 1950s and 1960s, however, data became available on oceanic conditions across the entire Pacific. It was soon realised that it is a part of a much broader scale phenomenon which is associated with unusually warm waters that occasionally occur across much of the tropical eastern and central Pacific. Typically, the events tend to recur every 3 to 7 years but there is no real regularity to their occurrence.

La Niña, El Niño‘s counterpart, is characterized by cooler than normal sea surface temperatures across the same expanse of the Pacific as that of El Niño. It usually follows - and is followed by, the occurrence of the El Niño with no dependability. Once either event develops it shows an inclination to persist for approximately one year with occasional life spans for 18 months or more.

The Climatic Changes Associated With El Niño-La Niña