The El Niño: What it is and What it Means for Us

In this closer look at the El Niño, we examine the details of this weather phenomenon and discuss causes, past impacts, and future expected outcomes.

By Aaryaman Aashind

Governments around the world have started making preparations in anticipation of the El Niño. This weather phenomenon significantly impacts both rains and temperatures, and its affects are felt across the globe.

With an increasingly globalized economy and interconnected supply-chains, a drought or a failed monsoon in one part of the world is a cause for worry for a country in a different part of the world. Even if the geographic impact of the El Niño is relatively localized, the economic impact may be more far-reaching.

What’s more? El Niño may also heighten the impact of global warming.

According to World Meteorological Organization (WMO) Secretary-General Prof. Petteri Taalas, “A warming El Niño is expected to develop in the coming months and this will combine with human-induced climate change to push global temperatures into uncharted territory. This will have far-reaching repercussions for health, food security, water management and the environment. We need to be prepared.”

The world has already recent food supply chain disruptions due to the coronavirus pandemic and the war in Ukraine and it is likely that the El Niño may cause another disruption in the near future.

What is the El Niño?

According to Professor Timothy Creyts of Columbia University, “El Niño is a change in the warm pool in the eastern Pacific. It is a sub-decadal phenomenon with the ENSO (El Niño Southern Oscillation) describing the switch between El Niño and La Nina.”

Let’s break this down.

The water surface temperatures in the central and eastern regions of the Pacific Ocean experience periodic warming and cooling. An El Niño event can cause the sea surface temperatures to tend towards being warmer than average. This warming can last for a period of nine to twelve months, but can even persist for years.

Under usual circumstances, the Pacific Ocean experiences east-to-west winds. This wind is responsible for shifting warm water from South America towards Asia. Cold water from the depths of the ocean floor rises to replace the warm water.

However, this process is disrupted when an El Niño event occurs.

During the El Niño, the force of the east-to-west winds diminish. This means that warm ocean water does not move from South America towards Asia. Hence, the overall sea surface temperatures of the central and eastern regions of the Pacific Ocean are higher than usual.

While discussing the El Niño, it is essential to contrast it with the La Nina. The La Nina causes a cooling effect on the ocean surface temperatures. The El Niño and La Nina cycle is called the El Niño Southern Oscillation (ENSO). This cycle has a significant impact on the Earth’s weather patterns. The ENSO occurs every two to seven years, on an average.

Scientists do not know the exact causes of the El Niño or the La Nina.

Scientists believe that El Niño events have been occurring for thousands of years. There have been 26 El Niño events since the start of the 20th century.

The El Niño: Map showing sea surface temperature anomalies in the Pacific Ocean on October 15, 2015.
The largest El Niño event of the 21st century was that of 2015-16. 
Chart of anomalous ocean surface temperatures in October 2015.
Credit: National Environmental Satellite, Data, and Information Service –

When Will El Niño Occur?

According to the National Oceanic and Atmospheric Administration (NOAA) of the United States, which is one of the prominent climate organizations in the world, we are already experiencing El Niño conditions. This announcement was made on 8th June, 2023.

However, experiencing El Niño conditions does not make it a full-blown El Niño event since these conditions may reverse. If these conditions persist till October, then the NOAA will conclude that an El Niño event is occurring.

Meanwhile, the WMO has categorically stated that a 90% probability exists for a moderate El Niño event to last till at least the end of the year. There is a 56% chance that a strong El Niño event occurs. Essentially, the difference between a moderate and a strong El Niño event is how warm the ocean surface temperate in the Pacific gets. A stronger El Niño event is also more likely to have a greater impact on rains and temperatures around the world.

Even though it is likely that El Niño develops in 2023, we will start experiencing most of the heat from the event in 2024. But 2023 is still likely to become the hottest year on record (globally) in history. The last El Niño event occurred in 2016, which is the current hottest year on record ever.

In fact, it seems likely that temperature records will continue to be broken in the near future. A joint investigation and report by the UK Met Office and the World Meteorological Office has concluded that there is a 66% probability of global annual temperatures being higher by 1.5 degrees Celsius since pre-industrial levels.

As Chris Hewitt, the WMO’s director for climate services has stated, “This is not to say that in the next five years we would exceed the 1.5C level specified in the Paris agreement because that refers to long-term warming over many years. However, it is yet another wake-up call that we are not yet going in the right direction to limit the warming to within the targets designed to substantially reduce the impacts of climate change.“

Impact of El Niño in the Past

It is worthwhile to explore what happened during these years, so that we can better anticipate what might occur this year and next year.

The impacts of El Niño on rains and temperatures in the past have been well-recorded. Notable super El Niño events took place in 1972-1973, 1982 -1983, and 1997-1998, while the last El Niño occurred in 2015- 2016.

In 2015 – 2016, the El Niño was coming up in addition to an already warmed Pacific Ocean surface temperatures caused by climate change (this double whammy is what we’re likely to experience in 2023 – 2024 as well).

An El Niño event usually brings more extreme weather conditions around the world.

As observed by Professor Cryets, “The big thing is that with an increase in temperatures comes an increase in the speed of the water cycle. Evaporation happens faster, so we see an increase in the rate of uptake of water by the atmosphere.

Dry areas get drier and wetter areas can experience heavier, faster rains. An increase in temperatures causes something like El Niño to have more severe effects on cities and infrastructure. For those areas that experience droughts in El Niño years, the droughts will be longer.”

For example, Brazil, Paraguay, and Uruguay received higher rainfall during the 2015-2016 event than their long-term averages from December to February. This lead to the displacement of thousands who were affected by floods and the overflowing of rivers.

In contrast, the northern portion of the South America continent experienced undue dryness. The worst affected was Central America which experienced serious drought which was borne by countries like El Salvador, Honduras, and Guatemala. A drought was experienced by Caribbean nations as well.

Similar patterns occurred in Africa as well. Countries like Kenya and Tanzania experienced too much rainfall while southeastern Africa experienced too little rainfall. Due to failed rains, Zimbabwe declared a state of Emergency and large populations became food insecure. Floods displaced people in Kenya and Somalia (more than 200,000 people).

It is always likely that South and South-Eastern Asia experiences depressed monsoons, which is what happened in 2016 as well.

Essentially, while parts of the world suffered from drought, other parts suffered from floods. This is not all. Changing weather patterns had also led to increased frequency of outbreaks of disease that affected cattle as well as crops leading to more food insecurity. Water-borne diseases like Cholera and Typhoid broke out along with higher incidences of Malaria.

Expected Outcomes in 2023 and 2024

The affects of El Niño is expected to be felt across the world.

Professor Creyts tells us, “a typical response to El Niño in North America is felt in the winter and early spring.  This depends on the strength of the El Niño. California can see stronger storms: in southern California, these are rain events that lead to erosion and landslides.  In northern California, these can lead to a higher snowpack, so more water and melt during spring. The southeast US typically sees higher precipitation in the winter.”

Similarly, we can expect severe heatwaves in eastern Australia, Central America, Indonesia, and South Asia. In contrast, we can expect flooding in Central Asia, the Horn of Africa, and parts of South America. 

But what can be done to prepare us for a tough El-Nino year?

“Typically, infrastructure resilience takes years to build. When we think about changes in temperature or precipitation following either an oscillation in the climate system (ENSO) or long term change (warming global climate), the infrastructure needs to be planned methodically.  Higher precipitation can lead to flash floods. Drought-prone areas need to plan water resources very carefully,” says Professor Creyts.

“As climate changes, tail events linked to a phenomenon like El Niño can become more severe.  Lately, we’ve seen a lot of flooding in cities that is directly linked to a lack of foresight in the planning process. Cities need to prepare ahead of time.”

It remains to be seen how prepared we are for El Niño in 2023 – 2024.

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