A naturally occurring climate phenomenon formed in the Pacific between the west coast of South America and east coast of Asia (Australia, Indonesia).
A climate anomaly manifesting near the west coast of South America (chiefly the coast of Peru) every three to five years, normally beginning shortly after Christmas. Primarily characterised by a sudden rise in surface temperature in the otherwise relatively cold Humboldt Current in the southeast Pacific, caused by a faltering of the southeast trade wind. In coastal waters – where the normally nutrient-rich deep water is replaced by nutrient-poor water from shallower layers – it typically leads to pronounced, widespread fish kills with corresponding, often catastrophic commercial consequences. This is accompanied by unusually heavy rainfall over the otherwise arid, desert-like coastlands, leading to erosion.