The Australian Bureau of Meteorology joined their US counterparts, the National Oceanographic Atmospheric Administration, on Tuesday morning in announcing the end of the natural climate pattern La Niña in the Pacific Ocean.
La Niña has been responsible for record-breaking rainfall in eastern Australia, an above-average number of tropical cyclones in the Atlantic Ocean and drought in eastern Africa.
Forecasters are now looking at El Niño for later in 2023, which would have different implications for weather patterns around the world.
La Niña is the phase of the El Niño Southern Oscillation (ENSO) pattern where the water in the Pacific Ocean is cooler than average, the opposite of the warmer El Niño phase.
ENSO would normally transition from La Niña to El Niño every two to five years, but in 2022, Pacific waters cooled for the third consecutive year, bringing a rare “triple-dip” La Nina.
The heaviest impact of this La Niña period was in eastern Australia, where severe flooding and record-breaking rainfall occurred in 2022.
In Sydney, the annual rainfall record was broken in October and by the end of the year 2577 mm of rain fell, surpassing the previous record of 2244 mm set in 1950.
Sydney sees wettest year on record
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La Niña also contributed to a record-breaking Atlantic hurricane season in 2020 and the third most active season in 2021.
In February and early March, sea surface temperatures rose in the eastern Pacific, and now the Bureau of Meteorology (BOM) and the National Oceanographic Atmospheric Administration (NOAA) have declared ENSO to be “neutral,” so neither La Nina nor El Nino.
Forecasters expect neutral conditions to persist into the spring and early summer of 2023 in the Northern Hemisphere.
Apart from that there are some predictions of a warming of the Pacific which will lead to El Niño developing towards the end of the summer so BOM has issued an “El Niño watch” meaning there is a 50% chance that El Niño develops.
Although forecasts from the El Niño Southern Oscillation are more uncertain in the spring than at any other time of the year, it still gives a good indication of what to expect later this year and into 2024.
What could El Nino bring?
The biggest impact of El Nino, especially if it’s a strong one, is on the global average temperature which could rise by another 0.2C.
As the Pacific warms, this extra heat is released into the atmosphere, much like a boiling pot of water releases steam and raises the temperature in a kitchen.
The warmest year on record was in 2016, when a strong El Niño caused global temperatures to rise.
How much impact a potential El Niño will have on global temperatures in 2023 is likely to be minimal, as it won’t start until later this year.
However, now that the cooling La Niña phase is over, the Met Office suggests temperatures will be between 1.08C and 1.32C above pre-industrial levels.
Met Office predicts that 2023 will be hotter than 2022
Some of the other impacts of El Niño include drier and hotter weather in Australia, potentially leading to greater wildfire risks, flooding in eastern areas of South America such as Peru and Ecuador, and drought in the Amazon region.
El Niño is also a factor that could reduce the development of tropical cyclones in the Atlantic Ocean, which could lead to fewer hurricanes.
As for the impact of El Niño on UK weather, this is more uncertain, but further research suggests this is a factor in potentially colder winter weather.