Context:

A warming world is reshaping the El Niño–La Niña cycle and the way scientists label and interpret it. New research links an unusually prolonged La Niña phase to the recent spike in Earth’s energy imbalance and higher global temperatures, while NOAA has overhauled how it defines and detects the transition between phases. The updated labeling implies more La Niñas and fewer El Niños, influencing forecasts and potential impacts on global climate patterns. With a likely El Niño developing later this year, experts warn it could push temperatures to new records and drive extreme weather, even as it may dampen Atlantic hurricane activity. The shift underscores that ‘normal’ in climate metrics is moving, requiring adaptive monitoring and interpretation going forward.

Dive Deeper:

• Researchers quantify how a longer-than-usual La Niña period contributed to about a quarter of the recent rise in Earth's energy imbalance, with major portions tied to greenhouse gas emissions and other factors, helping explain the temperature spike since 2023.

• The study emphasizes that El Niño and La Niña cycles are being reshaped by overall warming, altering the distribution of heat between the ocean and atmosphere and thereby changing global weather patterns.

• NOAA has changed its labeling framework from a fixed three-region temperature differential to a relative index anchored to the tropics, reflecting how warming shifts what counts as normal conditions.

• As a result of the new method, the system is expected to record more La Niñas and fewer El Niños, altering expectations for tropical-warm-water events and their climate consequences.

• Forecasts anticipate an El Niño developing later in the year, which could raise global temperatures further in 2027 and potentially intensify extreme weather while possibly reducing Atlantic hurricane activity in the near term.

• Experts caution that the evolving definitions and feedbacks mean the public should expect more variability and that climate records from earlier eras may no longer map neatly onto current conditions.