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Scientists have uncovered a new weather pattern that might reshape how we view the global climate. Known as the Southern Hemisphere Circumpolar Wavenumber-4 Pattern, or simply the "new El Niño," this phenomenon is located in the southwestern subtropical Pacific, near Australia and New Zealand.
The El Niño–Southern Oscillation (ENSO) has long been recognised for its impact on global climates, but this newly discovered pattern could be just as significant. The region influencing this pattern is relatively small, yet its effects stretch across the entire Southern Hemisphere.
An international team of researchers made the discovery, and their findings suggest that understanding this new pattern will be crucial for predicting future climate changes. "This discovery is like finding a new switch in Earth's climate," says meteorologist Balaji Senapati from the University of Reading in the UK.
The team used 300 years of real-world data and advanced climate models to track the W4 pattern, which features four alternating zones of warm and cool air. They discovered that the small region near Australia and New Zealand plays a key role in controlling this pattern. Changes in ocean temperatures there affect atmospheric temperatures in the Southern Hemisphere's subtropical and mid-latitude regions.
As wind patterns shift, they alter the depth of the warmer water layer in the ocean, which in turn affects atmospheric temperatures. Westerly winds then transport this warmed or cooled air globally, creating a unique climate pattern that differs from El Niño and its counterpart, La Niña.
Understanding this new pattern could improve weather forecasting and climate predictions, especially in the Southern Hemisphere. It might also help explain recent climate changes and improve our ability to predict extreme weather events.
The new El Niño appears to start influencing weather during the Southern Hemisphere’s summer, from December to February. Although this pattern has only recently been identified, researchers believe it has been affecting global weather for some time.
While the study did not delve into how changes in this new pattern might unfold, the researchers note that the Southern Hemisphere is experiencing more dryness, warming, and storms. This new pattern could help explain these trends.
