Variation in time
Some years around Christmas time the fish suddenly disappear from the Peruvian coast. The lack of fish causes starvation in the fishing villages. Those that make a living collecting guano to sell as fertilizer also experience a difficult time when the fish-eating birds, that were the source of guano, die. The phenomenon is known as El Niño, the little boy (Christ).
In a normal year, cold water from the deep part of the Pacific wells up toward the Peruvian coast. The cold bottom water is rich in salts, phosphorus and nitrogen, and when it mixes with the thin layer of warm surface water the plankton production increases. Fish are higher up in the plankton foodchain. This leads to abundant ocean fishing which is the normal state outside Peru and is known as La Niña, the little girl. So why does El Niño occur?
For certain reasons water temperature in the westernmost part of the Pacific rises some years, and the trade winds move the warm water east toward South America. Since warm water expands, the water forms a low wave moving in from the west toward Peru. When this mass of warm water arrives at the coast the cold water is cut off. Without nutrients from the depth of the ocean plankton production in the warm surface water decreases abruptly. El Niño has arrived. The ocean phase that causes El Niño lasts for about a year, before La Niña returns with an abundance of fish.
Though it is often claimed in the media that this phenomenon is the result of a climate change caused by human carbon dioxide emissions, this is not true. It is an expression of normal variation in the ocean. So how often does El Niño occur?
Because the rhythm is not caused by interplanetary movements like tidal water is, it is difficult to predict it exactly. It can be said with certainty, however, that the rhythm varies, sometimes being faster, sometimes slower:
1650–1749 1 / 6.0 years
1750–1849 1 / 4.6 years
1850–2000 1 / 3.4 years
The changes in rhythm between these periods were abrupt, which shows that human activity has no part in it. The phenomenon has actually occurred for at least 20 million years, much longer than human beings have existed. We know a lot about this because El Niño causes mass deaths. The animals that die become fossilized and this way we can tell when El Niño has occurred. The rhythm is also traceable in the coral reefs in the west Pacific, and in the ocean level of the Galápagos Islands.
Like El Niño, most natural processes follow a pattern that we need a long series of observations to understand. This is why we built TRITON.