Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 6 1st Alexander von Humboldt International Conference 2006 10.5194/adgeo-6-195-2006 http://www.adv-geosci.net/6/195/2006/ http://www.adv-geosci.net/6/195/2006/adgeo-6-195-2006.html http://www.adv-geosci.net/6/195/2006/adgeo-6-195-2006.pdf 195 199 2006-02-06 Relationship between the 1997/98 El Niño and 1999/2001 La Niña events and oil palm tree production in Tumaco, Southwestern Colombia M. C. Cadena A. Devis-Morales J. D. Pabón I. Málikov J. A. Reyna-Moreno J. R. Ortiz División de Oceanografía, Centro Control Contaminación del Pacífico – CCCP, Vía al Morro, Capitanía de Puerto, San Andrés de Tumaco, Nari˜no, Colombia Universidad de Concepción, Cabina No. 9, Casilla 160-C, Concepción, Chile Instituto de Hidrología, Meteorología y Estudios Ambientales – IDEAM, Carrera 10 #20–30 piso 7, Bogotá Colombia Departamento de Geografía, Universidad Nacional de Colombia, Avenida Carrera 30 No. 45-03, Edificio 212, Ciudad Universitaria, Bogotá, Colombia Although the relationship between ENSO events and oceanographic and meteorological conditions of Southwestern Colombia is well-known, very little work has been done to assess the related socio-economic impacts. This is the first effort made to determine the effect of such events on local climate and the impact of this variability on oil palm tree (<I>Elaeis guineensis</I>) production in the Tumaco municipality, which is located on Colombia's Pacific coast. First, we studied the correlation between sea surface temperature anomalies (SSTA) in the various El Ni&#241;o regions and those observed off Tumaco. Next, we scrutinized the ENSO impact on regional climatic indicators, e.g. active solar radiation (hrs/day), air temperature (&deg;C), and rain (mm). Finally, we analyzed the relationship between ENSO, Tumaco climate variability, and oil palm production (tons/hectare-month). Hours of active radiation increased (decreased) under El Ni&#241;o (La Ni&#241;a) conditions, as did average monthly precipitation rates and air temperature. ENSO-related climatic variability also had an important effect on the different developmental stages of the oil palm tree, thereby affecting its production. The worst scenario was found during La Ni&#241;a, when reduced intensity of the rainy season (second semester) caused severe droughts in the region.