During normal years, when there is a steep thermocline tilt, the cold, deep currents flowing from Antarctica up the west coast of South America are allowed to upwell, bringing essential nutrients that would otherwise lie at the bottom. Phytoplankton living near the surface depend upon these nutrients for survival. In turn, fish and mammals depend upon phytoplankton as the very foundation of the marine food chain. As previously explained, the warm surface waters of an El Niño prevent this upwelling, effectively starving the phytoplankton population there and those animals higher up the food chain that depend upon it. Fishermen in Peru and Ecuador generally suffer heavy losses in their anchovy and sardine industries.
At Christmas Island, as a result of the sea level rise during the 1982-83 El Niño, sea birds abandoned their young and flew out over a wide expanse of ocean in a desperate search for food. Along the coast of Peru during that same time period, 25 percent of the adult fur seal and sea lion populations starved to death, and all of the pups in both populations died. Similar losses were experienced in many fish populations.
Meanwhile, over a six-month period about 100 inches of rainfall fell in Ecuador and northern Peru--ordinarily a desert region. Vegetation thrived and the region grew lush with grasslands and lakes, attracting swarms of grasshoppers and, subsequently, birds and frogs that fed on the grasshoppers. Many fish that had migrated upstream during the coastal flooding became trapped in the drying lakes and were harvested by local residents. Shrimp harvests were also very high in some of the coastal flood regions, but so too was the incidence of malaria cases due to thriving mosquito populations.
El Niño's impacts on weather patterns
While El Niño is known to lower the probability of hurricanes in the Atlantic, it increases the chances of cyclones and typhoons in the Pacific. The 1982-83 El Niño is estimated by NOAA to have caused some $8 billion in damages due to floods, severe storms, droughts and fires around the world.
return to:What is El Niño?
What is El Niño?