La Niña "triple episode" will affect 18 million people

The United Nations has issued a warning that for the first time in this century, a "triple episode" of La Nia could occur. If this occurs, it could have devastating consequences for approximately 18 million people living in Africa, where droughts and subsequent fires could occur.

La Niña "triple episode" will affect 18 million people
Water dam in Mexico. Image: courtesy of Dr. Christian Domínguez

A third La Niña episode would aggravate the drought in the Horn of Africa, which threatens the livelihoods of some 18 million people, the World Meteorological Organization (WMO) warned. The meteorological agency of the United Nations (UN) warned that "there is a 70% probability that La Niña will continue during September and November of this year".

If it occurs, it would be the first time in this century that there is a "triple episode" of La Niña, a climatological phenomenon that began in September 2020. It was indicated that, if it extends until the end of the year, it would reach three consecutive boreal winters, and hence it is considered a "triple episode".

What is La Niña?

La Niña is a phenomenon that cools the surface waters of the central and eastern parts of the equatorial Pacific on a large scale, in addition to producing other changes in tropical atmospheric circulation, such as winds, pressure, and precipitation.

Strictly speaking, La Niña and El Niño are the two opposite phases of the same weather pattern, known as El Niño-Southern Oscillation (ENSO): a natural phenomenon of surface temperature anomaly in the equatorial Pacific Ocean, which has important consequences for climate around the globe.

El Niño is a warm phase and usually appears first: it occurs when air pressure conditions change, weakening the trade winds in the southern Pacific hemisphere. This is the name given to the winds that usually blow from east to west in that ocean, from subtropical regions of high pressure to equatorial areas of low pressure.

La Niña occurs when the opposite phenomenon occurs: when the trade winds are very strong, the rise of deep cold water in the equatorial zone is reinforced and the sea temperature falls below normal. Specifically in the case of the Horn of Africa (the eastern part of the continent), what La Niña produces is a strong drought.

In this regard, WMO Secretary-General Petteri Taalas warned that "the latest data on La Niña confirm regional climate projections that point to a worsening of the devastating drought in the Horn of Africa, the consequences of which will affect millions of people". An estimated 18 million people are facing severe famine as a result of the worst drought in 40 years in that region.

La Niña vs. El Niño

"La Niña" is a very cold sea surface temperature anomaly in the tropical Pacific and is part of a natural phenomenon called El Niño-Southern Oscillation (ENSO). "La Niña" is the negative (cold) phase. Meanwhile, the warm phase is "El Niño", which generates very high temperatures in the Tropical Pacific and also induces wind changes at a global level.

ENSO was discovered in the early 1900s and since then its influence on the world climate has been studied. The interesting thing is to take advantage of the information provided by current climate forecasts so that authorities can make scientifically based decisions on how they will manage water use, to avoid havoc in the lives of people and communities.

It is also up to citizens to make better use of the resource, avoid leaks, and implement technologies that allow them to capture rainwater, such as "water harvesting", which can be used for cleaning.