El Niño 101 | National Geographic
A natural force of nature unlike any other, El Niño is capable of unleashing a fury of climate changes and natural disasters that span from Alaska all the way to South America and beyond. What causes El Niño, and how are we affected by it?
El Niño is not a storm but rather a weather phenomenon in the Pacific Ocean. During an El Niño, the surface water temperature warms up, leading to complex weather patterns. South American fishermen in the 19th century, describing warmer waters during Christmas time, coined the name El Niño, Spanish for "the Blessed Child."
Nowadays, when sea surface temperatures in the equatorial Pacific Ocean rise 0.5 degrees Celsius over their historic average for three consecutive months, and once atmospheric conditions and rainfall patterns shift accordingly, scientists officially declare an El Niño. An El Niño event takes place about every two to seven years. Normal east to west trade winds over the Pacific weaken, and warm water that normally travels westward is now moving toward the east. Moisture then rises into the air, and the effects of El Niño are felt throughout the Americas.
In the ocean, warm water pushes colder water downward, blocking the important upwelling of nutrient-rich waters from the bottom. This causes some marine life to migrate to colder waters. Animals that normally feed on the sea life suffer, and fisheries throughout Central and South America suffer too.
But El Niño's most noticeable repercussions are felt on land. In the western United States and Central and South America, the warm air and moisture lead to increased storms, rainfall, floods, loss of life and property, and the increase of some vector-borne diseases like malaria, even in places where they don't normally occur.
In Southeast Asia and Australia, the opposite takes place. These areas suffer from droughts, wildfires, and colder ocean waters. In 1997 and 1998, the world experienced the biggest El Niño in recorded history. Some estimates blame that El Niño for 2,100 deaths and 33 billion dollars in damages. Mongolia saw temperatures reach 108 degrees Fahrenheit, there was record flooding in Peru, and the U.S. saw storms in the Gulf Coast, flash flooding from California to Mississippi, and tornadoes in Florida.
Scientists are now better able to predict if and when an El Niño event will take place. This helps communities better prepare for the changes in weather patterns and better adapt to its repercussions.