The El Niño Southern Oscillation (ENSO) is the scientific way of describing how the temperatures in the atmosphere and the tropical Pacific-Sea-surfaces in the Central and Eastern equatorial Pacific vary from year-to-year between above and below average temperatures. El Niño events occur when the central and eastern equatorial Pacific ocean waters become much cooler than they normally are. Such changes can impact sea level pressures, sea surface temperatures, precipitation patterns, and winds on a very large scale .
The name “El Niño” (meaning “the boy child”) originates from before the 20th Century when Peruvian fishermen noticed that the waters off of the coast of South America were warmer than normal (most noticeably during the Christmas season), and that such an increase in ocean water temperatures impacted their fisheries .
Global effects of El Niño
El Niño events result in predictable shifts in temperature, precipitation and other weather patterns for up to a year or more throughout the globe that can lead to natural disasters such as floods, droughts, and other climate-related disasters. This predictability allows for decision makers to prepare for taking swift action on these potential disasters.
Most directly affected by El Niño events are regions that are located in and immediately surrounding the tropical equatorial Pacific. During El Niño events, there is likely to be an increasing low pressure and an increase in rainfall along the western coastal regions of North and South America. At the same time, the water temperatures of the western Pacific are likely to become cooler than usual, resulting in higher pressure conditions and decreased rainfall .
Decrease of available nutrients for fish
Under normal conditions, the equatorial coastal fisheries of South America receive cold and nutrient-rich water upwelling from the deep waters of the Pacific that feed and cultivate fisheries. However, during El Niño events, warmer waters and weaker trade winds reduce this cool water upwelling and thereby results in fewer nutrients that reach the fisheries.
This lack of oceanic nutrition can exhibit negative impacts on the entire local marine food chain, as well as negatively impact the production of local fisheries .
Increase of natural disasters
Physical disasters caused by El Niño events can include flooding, landslides, forest fires and fire-related pollution, tropical cyclones and hurricanes, and drought.
Other impacts of such global altered climate patterns include disease outbreaks, water shortages, negative impacts on hydropower energy resources, insect pest outbreaks on crops, crop failure, famine, and alterations in animal migration.
Staying safe during El Niño
Scientists and decision makers are helping us to fully understand how El Niño events impact the Earth and humanity, and allow us to more accurately anticipate the impacts of future events and how to prepare for them.
How vulnerable the region or a country is to El Niño events depends on a number of factors, including existing infrastructure, emergency preparedness of local and national governments, and well-informed public.
For example, a country that has fewer resources may have an increased vulnerability to El Niño related disasters such as fires, floods, droughts, and crop failures, rather than a country with ample resources and infrastructure. The most optimal time to prepare and plan for such natural disasters is before their occurrence, but this may be challenging for countries with limited resources .
Organizations such as the International Research Institute for Climate and Society offer disaster management with preparation training and resources to predict future climate events such as El Niño.