Earth’s Energy Imbalance, El Niño–La Niña Shift and the 2023 Global Temperature Surge

A recent study published in Nature Geoscience has explained the sharp rise in global temperatures since 2023, attributed to Earth’s energy imbalance and the shift from a prolonged La Niña phase to El Niño, alongside long-term human-induced climate change.

• Revision in El Niño–La Niña Classification
  • Scientists are updating the way El Niño and La Niña are labelled due to rapid warming caused by climate change.
  • Rising global ocean temperatures have shifted the baseline, making earlier thresholds less accurate.
  • The National Oceanic and Atmospheric Administration has revised its calculation method to determine when ENSO phases begin or end.
  • Under the new criteria, more events may be classified as La Niña, while fewer may qualify as El Niño despite warmer tropical waters.

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Key Findings of Study

• Unusual Triple Dip: From 2020 to 2023, Earth had an unusual “triple dip” La Nina without an El Nino in between. 
  • In a La Nina, warm water sticks to a deeper depth, resulting in a cooler surface. And that reduces how much energy goes out into space.
• Causes of  Increase in Earth’s Energy Imbalance:
  • About 23% of the recent increase in Earth’s energy imbalance is attributed to the unusually prolonged La Niña (2020–2023) phase.
  • Slightly more than 50% of the imbalance is linked to greenhouse gas emissions from the burning of coal, oil, and natural gas.
• Insights on Earth’s Energy Imbalance: 
  • An increase in Earth’s energy imbalance means more heat is trapped, leading to higher global temperatures.
  • Around 75% of the recent rise in energy imbalance is attributed to the combined effect of:
    • Long-term human-induced climate change, and
    • The shift from a prolonged three-year La Niña (cooling phase) to a warming El Niño phase.
• Rise in Average Monthly Temperature: Earth’s average monthly temperature took a noticeable jump up from the long-term upward trend connected to human-caused climate change in early 2023, and that increase continued through 2025.

About El Nino

• El Nino,  meaning “the little boy” in Spanish, is commonly known, refers to an abnormal warming of surface waters in equatorial Pacific Ocean.
  •  It is known to suppress monsoon rainfall. 
• It was first noticed by scientists in the 1920s.
• It occurs on average every two to seven years, and episodes usually last nine to 12 months.  
• Formation: 
  • It forms when the trade winds blowing east-to-west along the equatorial Pacific slow down or reverse as air pressure changes, although scientists are not entirely sure what kicks off the cycle.
  • Because the trade winds affect the sun-warmed surface waters, a weakening causes these warm western Pacific waters to slosh back into the colder central and eastern Pacific basins.

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La Nina

• La Niña means Little Girl in Spanish. La Niña is also sometimes called El Viejo, anti-El Niño, or simply a cold event.
• It is the opposite of El Niño, which is the abnormal cooling of sea surface waters in the same region, and is known to aid rainfall over India. 
• The La Niña phenomenon was discovered only in the 1980s.

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