El Niño and La Niña are climate events that periodically visit the Galapagos Islands. What are they, and how will they affect your Galapagos vacation?
Both phenomena are part of the El Niño-Southern Oscillation (ENSO) cycle that disturbs the Pacific Ocean basin. El Niño is the dry phase of the cycle, and La Niña is the wet phase. El Niño conditions arise approximately every five years, with severe ones occurring every 10 to 20 years. La Niña usually comes immediately after an El Niño finishes. Such events can last from five months to almost two years. The ENSO cycle affects not only countries in the Pacific Ocean basin, but also Antarctica, Europe and Africa.
El Niño and La Niña alter the flow of the three major currents that wash the Galapagos archipelago: the warm Panama Current from the north; the Cromwell Current, which brings nutrients from the deep sea to the surface; and the cold South Equatorial Current / Humboldt Current from the east. This latter current is the most affected by El Niño, and perhaps the most important to the Galapagos ecosystem.
What is El Niño?
El Niño (The Little Boy) is named for the Christ child, as it usually begins around Christmastime. Its most striking feature is that ocean temperatures rise in the eastern Pacific. In addition, high pressure reigns over the western Pacific Ocean and low pressure over the eastern Pacific. Equatorial trade winds in this part of the world usually flow from east to west. However, during El Niño, they weaken or may even reverse direction.
In some years, El Niño is weak, and in others, it is strong. During the last half-century, severe El Niño events have happened in 1972-1973, 1982-1983, 1997-1998 and 2015-2016.
Even though El Niño primarily is felt in the central and eastern tropical Pacific basin, its effects are also felt elsewhere. In Australia, warmer temperatures, reduced rainfall and drought conditions can occur. The same conditions occur in North America, all along the Pacific coast from Canada through Central America. Central Canada also has warmer, dryer weather, whereas the Gulf Coast and Florida have more rainfall.
In South America, droughts occur in Colombia, Venezuela and Brazil. The Pacific coast region, as well as the southern part of the continent, experience more rain. The Atacama Desert of northern Chile, one of the driest regions of the world, is covered with flowers.
What is La Niña?
La Niña (The Little Girl) has been called an anti-El Niño. It is the direct opposite of the El Niño phenomenon. The equatorial seas in the eastern Pacific Ocean basin are cooler than normal. Air pressures are high over the eastern ocean and low over the western.
In Australia, La Niña brings increased rainfall and cooler temperatures. In the U.S., temperatures in the Northwest are cooler than normal and in the Southeast, they are warmer. Further south, Peru and Chile suffer droughts, whereas places like Bolivia and Brazil can experience catastrophic flooding.
How El Niño and La Niña Affect the Galapagos Islands
In the Galapagos, the effects of El Niño and La Niña are strongly felt by the islands’ unique flora and fauna. The ecosystem goes awry, especially when a severe El Niño strikes.
During El Niño, the cold Humboldt Current does not arrive. This current flows northward from Antarctica and runs along the South American Pacific coast. When it reaches northern Peru, it veers westward to the Galapagos Islands and becomes known as the South Equatorial Current. Without this cold water, nutrients necessary for marine iguanas, penguins, sea lions, blue-footed boobies and other iconic Galapagos species are scarce. This affects not only these animals’ survivability, but also their breeding. During the strong 1982-83 El Niño, 77% of the Galapagos penguin population died, and during the 1997-98 event mortality was 65%. Only 30% of the marine iguana population survived the 1982-83 El Niño, and those that made it through became thinner and shorter.
On land, the situation is quite different. Rains are frequent, and so the landscape is plusher. This increase of food favors land bird breeding. For humans, snorkeling, swimming and diving are more pleasant because the sea is warmer.
The effects are exactly opposite when La Niña arrives. The sea is cooler and more nutrient-rich, a boon to marine life. Not only are penguins and sea birds thriving, but whales and their kin are more frequent visitors to the Galapagos archipelago. On land, however, drought reigns, making less food available for land iguanas, giant tortoises and land birds. During La Niña, these species breed less.
How will you know if El Niño or La Niña will be visiting the Galapagos Islands at the same time as you? International agencies like the U.S.’ National Oceanic and Atmospheric Administration (NOAA) and the Japan Meteorological Agency publish regular updates on the Pacific Ocean climate conditions.
Photo credit: NOAA