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La Niña Effects In Ecuador

M.Pilar Cornejo R. de Grunauer
Facultad de Ing. Maritima y Ciencias del Mar-ESPOL
TC3 Human Dimension Coordinator
Guayaquil, Ecuador
pcornejo@goliat.espol.edu.ec
www2.usma.ac.pa/~cathalac/etccc.htm

So much attention has been paid to El Niño that the announcement that its sister, La Niña, was coming demanded (or created) a need for information about its effects on Ecuadorian socioeconomic sectors. This need appeared not only because it was widely announced in the press, but because Ecuadorians thought that it could be as disastrous as El Niño which had caused over $3 billion in damages during 1997-98.

Common and current knowledge suggests that La Niña is the opposite of El Niño but reviewing the available literature, I found out some important facts:

1. There is still not much agreement about the term La Niña. Even though the most popular term is La Niña, some people still use "El Viejo" (the old one) or anti-El Niño, or the cold phase. The first time that I can recall this discussion about the name was early in 1989 before Dr. Philander published his book "El Niño, La Niña and the Southern Oscillation," (Philander, 1990, Academic Press, New York).

2. There is no universally accepted definition or even a "quest" for one about La Niña in a similar way that there has been for El Niño: What variables would define it? SST? Surface winds? How big must the anomalies be, for SST or surface winds? How long do the anomalies have to persist? And so on.

In spite of this lack of a normal definition, I will explain some of its effects in Ecuador. In terms of oceanic (sea surface) temperature anomalies, a time series from Ancon (near La Libertad, approximately 2S, 77W) for the period 1933-1985 and temperature transects along 2S (Sonnenholzer and Cornejo, 1994) for the period 1983-1988 shows that during cold events temperature fields drop some 2-3 C below normal for periods longer that the dry season (May through November), the thermocline (defined by the 20 C isotherm) surfaces, upwelling Kelvin waves are more frequent and the 13 C isotherm is stronger. But the effect on precipitation will never be equal and opposite during La Niña as opposed to El Niño. For Example, during El Niño it can rain 2 or 3 or even 10 times more than normal. But with La Niña, such is not the case once it stops raining, it cannot rain even less, so that the effect on normalized time series would be only to go, at the most, two standard deviations on the negative side. The effects on rainfall would be different; La Niña might increase the length of the dry season, it might also decrease the amount of rainfall during the rainy season and it might change the onset of the rainy season. These are important effects for the agriculture sector. Since there is little research on this, most of our data comes from research we have done on El Niño. Much more research is still needed on these issues.

Aquaculture

Some of the analyses of climate and socioeconomic information for Ecuador’s aquaculture sector shows that La Niña impacts are positive in the fisheries based on small pelagic fish such as sardines and the ones used for fish meal, while there are negative impacts on shrimp exports. In shrimp aquaculture the impact is negative, because during cold events wild shrimp larvae availability decreases and in the wild shrimp fisheries there is a large decrease due to shrimp population migration to the Panama area. The problem of the decrease of the availability of wild shrimp larvae was solved by the aquaculture sector after the cold event in 1985. Shrimp hatcheries were created where gravid female shrimps were used for spawning and where shrimp maturation took place in order to provide enough "seed" for the sector (Cornejo de Grunauer, 1998). Since then, the number of hatcheries has grown from three to more than 300 today. This information, along with the Niño3 index, have been used to develop a forecast model for shrimp larvae availability which is provided to the sector so its members can pursue mitigation and adaption measurements to prepare for the effects of this climate variability (Cornejo et al., 1997) [shrimp exports, along with banana exports, represent almost 60% of Ecuador revenues].

Other Economic Sectors

We know that there are adverse effects on other sectors such as human health, tourism, agriculture, clothes manufacturing among others, but we have not yet closely studied their relationship to La Niña to the extent necessary to quantify its effects. For example, during La Niña, air temperature is lower, and there might be more cloudiness. Thus, bananas on the plants might not attain the "grading" required for export. Other plants such as mangoes might not flower. Tourism at the beach resorts decreases because air and water temperatures are cooler than normal and not suitable for water sports. However, some effects might be positive, e.g., national clothes manufacturers might sell more sweaters and jackets than in a regular dry season due to winds.

In sum, there is a need for research on La Niña’s causes, its manifestations and its impacts. If one believes that there is enough evidence to support the occurrence of interdecadal variability as long term time series show, e.g., SSTs in Ancon, one has to be ready for the next “cold phase" of this interdecadal oscillation when we should expect more La Niñas than El Niños as happened at the beginning of this century. Right now at ESPOL and within the Trade Convergence Climate Complex (TC3), we have undertaken the task of understanding these climatic extreme events and their relationships with important socioeconomic sectors not only in Ecuador but also in the TC3 region.

References

Cornejo R. de Grunauer, M.P., 1998: Variaciones climáticas: Impacto del Fenómeno de El Niño/Oscilación Sur en la Acuicultura de Ecuador, Boletin. CENAIM, in press.

Cornejo R. de Grunauer, M.P., J. Calderón, J.L. Santos and G. Silva, 1997: Application of climate information in Shrimp Aquaculture: The Ecuadorian Case. ENSO SIGNAL, IRI/OGP/NOAA, September.

Sonnenholzner, S. and M.P. Cornejo-Rodríguez, 1995: "Subsurface Variability associated with the Cromwell Current between the Ecuadorian coast and 82 W," TECNOLOGICA-ESPOL.

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