What are El Niño and La Niña — and why should you care?

July 20, 2016
Photo by Kieran McConville

This year, El Niño has already affected 50 million people, devastating crops and leaving tens of millions without enough food. And La Niña is still to come. How do these complex weather patterns actually work? And why are they so destructive? We break it down in this explainer.

What are El Niño and La Niña?

El Niño and La Niña are complex weather patterns characterized by changing ocean temperatures around the equator in the Pacific Ocean.

Specifically, El Niño and La Niña are the opposite phases of the El Niño-Southern Oscillation cycle. In the area around the equator, normal weather patterns mean that winds carry warm water in the Pacific Ocean from the coasts of North and South America westward. But during El Niño, those winds weaken, and the east-west travel of warm water stops. When that happens, the winds reverse, and carry the warm water back towards the eastern Pacific, warming the ocean temperatures. El Niño is often followed by La Niña, an intensification of normal weather patterns, that causes a cooling of ocean temperatures, as the winds strengthen and blow all the warm water towards the west.

Image showing ocean temperatures during El Niño and La Niña

Credit: NOAA

This warming and cooling of surface water temperatures not only impacts the oceans, but also how much it rains on land, causing either droughts or flooding. El Niño and its warm waters are frequently associated with drought, while La Niña is usually linked to increased flooding — but because the global weather system is very complex, this is not always the case. For example, this year El Niño has caused both flooding and droughts in different places.

Map showing direction of warm water movement.

Credit: NOAA

Each El Niño or La Niña event lasts between 9-12 months, and occurs on average every 2-7 years — but they happen irregularly. While many scientists believe that climate change does impact El Niño and La Niña, they are not certain exactly how just yet.

What are the impacts of El Niño and La Niña?

El Niño and La Niña most strongly affect countries around the equator such as those in Central and South America, the Caribbean, Southeast Asia, and East and Southern Africa. While unpredictable weather cause problems for everyone, it most severely affects people who live in regions that rely heavily on agriculture, as too much or too little rain can be devastating for crops.


While drought can cause large crop failures, so can flooding. Flooding washes away seeds, and saturates soil with water so that crops cannot grow. If heavy rains follow periods of drought, precious topsoil can be washed away, too.

Woman stands in flood waters in Malawi

A women stands in flood waters that destroyed crops in Nsanje District, Malawi. Photo: Deborah Underdown

In many of the world’s poorest areas, people rely almost exclusively on rain-fed agriculture in order to feed their families. Concern works with many of these communities, and they’re the ones that El Niño and La Niña hit hardest.

Many of these communities are already working land that is poor or doesn’t receive a lot of rain. Each season, they can only harvest enough food to last them until the following season, leaving them few or no reserves to fall back on. A single drought or flood can therefore have ­devastating effects on these vulnerable communities. One failed harvest can mean families run out of food within weeks and will have nothing to eat until the next harvest many months away. Widespread droughts, like those we’ve been seeing with this year’s El Niño, can leave millions without food.

Child walk across barren fields

Children walk over what should be agricultural land in Tselmti woreda, Ethiopia. Nothing is growing in the current drought. Photo: David Hunn

Why are so many concerned about El Niño this year?

The 2015-16 El Niño is estimated to be far more devastating than previous events in the past — even worse than the strongest El Niño on record (1997-1998), which killed an estimated 21,000 people worldwide and caused $36 billion in damage to infrastructure.

So far, over 60 million people have been affected by the current El Niño crisis, which comes on top of already volatile and erratic weather patterns linked to climate change. Even though the direct effects of the weather pattern are winding down, the consequences of failed harvests will be felt until at least early 2017.

Dying maize in Zambia

A maize crop failure due to drought in the Senanga district, Zambia. Photo: Michael Hanly

Which countries are most affected and what is Concern doing about it?

Climate response is part of Concern’s core programming, and we help communities build resilience to climate change and climate-related disasters so that they are better prepared to cope. However, due to the severity of this year’s El Niño weather pattern, many countries need emergency assistance.

Within Africa, El Niño hit the eastern and southern regions hardest, affecting around 50 million people. Concern is providing El Niño-related support in ten countries in these regions, particularly Ethiopia and Malawi, which are under the biggest strain.

A mother and her children at a Concern supplementary food distribution in North Gonder, Ethiopia.

A Concern supplementary food distribution in North Gonder, Ethiopia. The monthly distributions are targeting under-5 children and pregnant and breastfeeding mothers who have been identified as malnourished. They are each given 14 pounds of corn/soy blend and one liter of oil. Photo: Kieran McConville


Ethiopia is suffering a severe drought due to two failed rainy seasons in a row — reportedly the country’s worst drought in over 50 years.

Facts and figures:

  • 10.2 million will required food aid in 2016  — this is in addition to the 7.9 million people receiving assistance through the Government Productive Safety Net Programme
  • 3.6 million people need emergency health interventions
  • An estimated 5.8 million people require emergency water supply and sanitation
  • Over 80% of the population depends on agriculture for their food and income, and crop and livestock production has dropped by 50-90% in some areas and has failed completely in other areas
  • 5.6 million farmers need emergency seeds
  • Children are missing out on up to three days of school a week because they must fetch water from long distances, take care of younger siblings while their mothers 
fetch water, or take livestock to areas in search of water sources

Concern’s response:

  • Targeting nearly 250,000 women and children with nutrition support
  • Reaching over 200,000 people with water and sanitation projects, including trucking thousands of gallons of clean water to drought-affected communities every day
  • Training over 1,100 Ministry of Health staff in treatment of acute malnutrition
  • Planning to provide seed for over 30,000 drought-affected households
People carrying water

People carry water trucked by Concern into the drought-affected Amhara region in Ethiopia. Photo: Kieran McConville


In mid-April, the President of Malawi declared a national disaster because of the ongoing drought and the country’s worst crop failure in a generation, a consequence of El Niño.

Facts and figures:

  • The UN estimates that 8.4 million people need food assistance
  • Even before the current food crisis, nearly half the children in Malawi were physically and mentally stunted due to malnutrition, one of the highest rates in the world
  • Maize (corn) is crucial in Malawi — it accounts for 95% of all crops harvested and it’s the staple food
  • This year, there’s a projected maize deficit of over 1.1 million tons
  • Poor households in most southern districts will soon be forced to engage in irreversible coping strategies in order to feed their families, such as: reducing the number and quality of meals; selling assets; withdrawing children from schools and going without critical healthcare

Concern’s response:

  • Emergency cash transfer program allowing 150,000 people to purchase food and other necessary items
  • Distributing drought-resistant and early-maturing maize and legume seeds
  • Emergency nutrition response including mass screenings to find and reach malnourished children, and ensure they receive appropriate treatment
  • Early recovery project focused on food and livelihoods, reaching 174,000 people
Field of winter maize

In 2015, before the droughts, this field of winter maize flourished on the floodplains of the Shire river in Nsanje district, Malawi. Photo: Kieran McConville

How you can help

We’re reaching hundreds of thousands of people whose lives have been devastated by El Niño — providing emergency food, water, seeds, and more.

Help us continue our work across the globe