After three La Niña summers, we are now officially in an El Niño climate cycle and are preparing for what might be Australia’s hottest ever summer on record.

This comes after what was just Australia’s (and Queensland’s) warmest recorded winter. El Niño and La Niña are opposite phases of the El Niño-Southern Oscillation (ENSO) phenomenon. ENSO is a natural climate pattern that involves periods of warming (El Niño) and cooling (La Niña) of sea-surface temperatures in the central equatorial Pacific Ocean, which have impacts on rainfall and temperatures across Australia. Many severe bushfires, such as those in Tara, Queensland, October 2023 occur during El Niño episodes.

Due to intensifying weather conditions caused by climate change, this means El Niño and La Niña events have become more frequent and intense, and are likely to continue trending this way unless we drastically cut our carbon emissions.

But what exactly is El Niño, and what type of weather events can Queenslanders expect because of it?

What is El Niño?

El Niño and La Niña are opposite phases of a natural climate pattern called the El Niño–Southern Oscillation (ENSO), which occurs because of the changing surface ocean temperature patterns in the Pacific Ocean. When the central and eastern equatorial Pacific is warmer than normal it is called El Niño, “the little boy” in Spanish, and when it is cooler than normal it is called La Niña, or “the little girl.”

El Niño occurs due to the weakening of the equatorial trade winds that normally blow westward from the Americas. Normally, these winds push warm surface water towards Australia’s east coast, but during El Niño, it accumulates in the eastern Pacific Ocean.

Within Australia, El Niño tends to be associated with warmer and drier conditions, while La Niña tends to see increased rainfall, more tropical cyclones and a decreased frequency of high temperature extremes. El Niño occurs on average every 3 to 5 years and once commenced can last for as little as 6 months or as long as 2 years.

What does El Niño mean for Queensland?

The consequences of an El Niño climate pattern extend far beyond a bit less rain. El Niño years also tend to bring warmer-than-average temperatures due to decreased cloud cover, especially in the second half of the year. These higher temperatures can worsen the impact of reduced rainfall by increasing evaporation.

Here are some of the potential impacts that El Niño may bring to Queensland.

Heatwaves

Heatwaves, as well as single-day temperature extremes and long-duration warm spells all increase in likelihood during El Niño events. A heatwave is defined as ‘three or more consecutive days of unusually high maximum and minimum temperatures in a given location’. In Australia, heatwaves usually range from 37°C to 42°C and are often combined with high humidity.

Heatwaves are our most dangerous natural hazard and are more lethal to Queenslanders than bushfires, cyclones, earthquakes, floods and severe storms combined. The most affected individuals are often those most vulnerable in our society, including the elderly, infants, and those with chronic medical conditions.

It is important to know how to reduce your risk during heatwaves. You can do so by keeping hydrated, cool, and staying out of the heat as much as possible.

If you have pets, make sure they have plenty of water and shade in a well-ventilated area. Cats are normally self-sufficient when it comes to keeping cool, but dogs may need some extra care. Reconsider that midday walk. Instead, opt for an early morning or sunset stroll, and stick to grassy areas. Signs your pets may be affected by the heat include behaviour changes, disinterest in food and water, isolating themselves and heavy panting.

If you discover sick, injured or orphaned wildlife which are not dangerous, you can contact 1300 ANIMAL (1300 264 625) for advice and to connect with local wildlife carers.

Coral bleaching

Scientists believe the main cause of coral bleaching is warmer ocean temperatures, and data supports a pattern of coral reef bleaching that aligns with El Niño. Mass coral bleaching events have occurred with increasing frequency since the early 1980s, and they have continued to get more severe. During autumn 2016, we saw the Great Barrier Reef’s worst coral bleaching event on record during an El Niño cycle.

In addition to the effects of El Niño, the Coral Sea faced abnormally high sea surface temperatures, 1.2°C in excess of average across much of the Great Barrier Reef region during winter and early spring. The current El Niño event could increase the likelihood of coral bleaching throughout the Great Barrier Reef.

The Great Barrier Reef Marine Park Authority monitors Reef conditions throughout the year. They release Reef health reports from May to November, along with weekly public updates during the summer season, based on forecasts, water temperature mapping, in-water surveys, citizen science, and aerial surveys.

The Australian Institute of Marine Science also monitors coral reefs along the Great Barrier Reef by maintaining a network of weather stations, temperature loggers and oceanographic moorings, which measure sea surface temperature, wind speed, humidity, air pressure and ocean circulation. The Great Barrier Reef Marine Park Authority will continue to closely monitor the Reef for conditions that may indicate thermal stress build up and coral bleaching alongside the Australian Institute of Marine Science.

Droughts

While El Niño doesn’t necessarily mean a drought will happen, the warmer-than-usual temperatures and reduced rainfall it causes can certainly contribute to drought conditions. In fact, most major Australian droughts have been associated with El Niño.

In addition to little rainfall, droughts place a huge strain on farmer’s crops and livestock, which can lead to price rises for fresh produce. Here are some handy storage tips that will help extend the freshness of your fruits and vegetables.

Have you heard of the Long Paddock? In Australian bushlore, the national stock route network is informally referred to as the "long paddock" given its geographic extent "the longest paddock in the world". During droughts, graziers in Australia practise "going on the long paddock" by moving their livestock across vast distances along designated routes, even crossing state boundaries. This method helps ensure that their animals have access to sufficient pasture. This unique journey is not only a way to cope with drought, but also an adventure that allows people to meet new individuals along the way.

Our Science Division, with support from the Queensland Department of Agriculture and Fisheries operate The Long Paddock website , which provides a range of climate and pasture condition information (historical and current) to assist the grazing community.