It looks like it’s all over for the extraordinary La Niña “triple dip” weather event that has cooled the Pacific Ocean and shaped Earth’s weather for the past three years. However, scientists have already warned that an El Niño warming phase could be on the way. If true, it could have some worrying planet-warming implications.
On March 14, the Meteorological Bureau of Australia announced that international climate models indicate that the El Niño-Southern Oscillation is currently neutral after three years of La Niña conditions.
They added that they are already moving directly to what they call an El Niño WATCH, as the probability of El Niño conditions occurring later in 2023 is over 50 percent.
If this prediction is correct, then El Niño has the potential to fuel heat waves and push global temperatures even higher than in recent years.
A strong El Niño can raise the Earth’s average temperature by as much as 0.2 °C (0.36 °F). With the planet already warming by about 1.2°C from pre-industrial levels, El Niño could push the global mean temperature above the much-heralded 1.5°C (2.7°F) threshold, a depressing milestone in the planet’s climate would mark crisis.
As always, nothing is certain.
“The three-year La Niña event has come to an end, but it’s not yet clear what comes next,” said Dr. Nandini Ramesh, senior natural hazards research scientist at CSIRO and the University of Sydney, in a statement.
“Predicting how the Pacific Ocean and atmosphere will evolve from this time of year (March-May) is notoriously difficult […] So while most forecasting models are now predicting an imminent El Niño, I wouldn’t place any bets just yet,” she added.
How La Niña affects the weather in North America. Photo credit: NOAA
What is La Niña and the El Niño-Southern Oscillation?
The El Niño-Southern Oscillation is a complex cycle that describes how a pattern of temperature fluctuations in the Pacific Ocean affects the world—from wind, temperature, and precipitation patterns to the intensity of hurricane seasons to the distribution of fish in the ocean and seas.
The cycle alternates between El Niño and La Niña phases every few years, with neutral phases in between.
During El Niño, seawater around the Central Pacific warms, causing a domino effect around the world. The warmer water causes the Pacific Jet Stream to move south and expand, causing drier and warmer weather to hit the northern parts of the US and Canada, but wetter weather in the southern states.
Over in the Atlantic Ocean, El Niño is actually weakening the hurricane season while increasing hurricane activity in the central and eastern Pacific basins.
La Niña is the other side of the coin and describes the cooling phase of the Pacific, which also has far-reaching effects on the global climate.
So what is a “triple dip” La Niña?
The past three years have been particularly unusual as the world has been in the midst of a rare “triple dip” La Niña that has lasted since around September 2020.
One of the most significant impacts of this “triple dip” La Niña was seen on America’s Atlantic coast, which experienced a record-breaking hurricane season in 2020 and the third-most active hurricane season in 2021.
The ferocious hurricane seasons are associated with La Niña as they remove the conditions that suppress storm formation in El Niño and encourage hurricane formation.
Man kayaking on the flooded streets of Brisbane, Australia – February 28, 2022. Credit: Alex Cimbal/Shutterstock.com
On the other side of the world, the ongoing La Niña impacted Australia, which was hit by incredibly wet weather and subsequent flooding in 2022.
“The Governing Board’s declaration that La Niña has ended marks the official end of the ‘Big Wet,’ a rare triple La Niña that was only the fourth since 1900 and the first in 22 years,” said Dr. Tom Mortlock, a senior analyst at Aon and Adjunct Fellow at the UNSW Climate Change Research Centre.
“This period was Sydney’s wettest year on record and led to what turned out to be Australia’s largest insured loss event of all time in the NSW and QLD floods of February to March. Current insurance industry claims for this event stand at A$5.76 billion, now surpassing the 1999 Sydney hailstorm (AU$5.57 billion) as Australia’s largest,” he added.