by The Australian Bureau of Meteorology joined its U.S. counterpart, the National Oceanographic Atmospheric Administration, on Tuesday morning in announcing the end of the Pacific Ocean’s natural La Niña climate pattern.
La Niña has been responsible for record-breaking rainfall in eastern Australia, an above-average number of tropical cyclones in the Atlantic and drought conditions in east Africa.
Forecasters are now monitoring El Niño for later in 2023, which would have varying consequences for weather patterns around the world.
La Niña is the phase of the El Niño Southern Oscillation (ENSO) pattern when the water in the Pacific Ocean is cooler than average, the opposite of the warmer El Niño phase.
ENSO would normally cycle from La Niña to El Niño every two to five years, but in 2022, Pacific waters cooled for a third straight year, bringing a rare “triple-dip” La Nina.
The most severe impacts of this period of La Niña were in eastern Australia, which experienced severe flooding and record-breaking rainfall in 2022.
In Sydney, the annual rainfall record was broken in October and 2577mm of rain fell by the end of the year, surpassing the previous record of 2244mm set in 1950.
Sydney sees wettest year on record
Evacuations as floods hit three Australian states
La Niña was also partly responsible for bringing 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 parts of the Pacific Ocean, and now the Bureau of Meteorology (BOM) and National Oceanographic Atmospheric Administration (NOAA) have declared ENSO to be “neutral,” meaning neither La Niña nor El Nino .
Forecasters expect neutral conditions to persist throughout spring and early summer of 2023 in the northern hemisphere.
Additionally, there are some predictions of Pacific warming leading to the development of El Niño by late summer, so BOM has released an “El Niño Clock” which means there is a 50% chance that El Nino developed.
While Spring El Niño Southern Oscillation predictions are more uncertain than any other time of year, they still give a good indication of what we can 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, affects the global average temperature, which may rise an additional 0.2°C.
As the Pacific Ocean warms, that 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 2016, when a strong El Niño pushed up global temperatures.
How much of an impact a potential El Niño will have on global temperature in 2023 is likely to be minimal as it is not expected to begin until later this year.
However, with La Niña’s cooling phase over, the Met Office suggests temperatures will be between 1.08C and 1.32C above pre-industrial levels.
Met Office forecasts 2023 will be hotter than 2022
Some of the other effects of El Niño include drier and hotter weather in Australia potentially leading to greater risk of wildfires, flooding in eastern areas of South America such as Peru and Ecuador, and drought in the Amazon.
El Niño is also a factor that could reduce the development of tropical cyclones in the Atlantic and thus lead to fewer hurricanes.
As for El Niño’s impact on UK weather, that’s more uncertain, but ongoing research suggests it’s a factor in potentially colder winter weather.
