El Niño is a weather phenomenon that develops across the Pacific Ocean. Essentially it is a band of anomalously warm ocean water temperatures that develops off the west coast of South America.
El Niño causes climatic changes across the Pacific and can result in severe droughts on the western Pacific while the eastern Pacific experiences anomalously high rainfall and catastrophic floods.
These extreme weather events typically occur once every 20 years but a new study published in the journal Nature Climate Change suggests that extreme El Niño events could occur twice as often due to the effects of global warming.
The last such event occurred in 1997/98 in which the anomalous conditions caused widespread environmental disruption including the disappearance of much marine fauna in the Pacific. The impacts affected every continent and claimed an estimated 23,000 lives worldwide causing USD 35-45 billion in damage.