Why the Past Three Years Have Been the Warmest on Record?

Context

According to the Copernicus Climate Change Service, the year 2025 was the third-warmest year ever recorded, with the global mean surface air temperature 1.47°C above pre-industrial levels (1850–1900).

Reasons Behind Record-Breaking Warmth

• Unabated Accumulation of Greenhouse Gases: Atmospheric concentrations of CO₂, methane, and nitrous oxide continue to rise due to fossil fuel combustion, deforestation, and industrial activity.
  • CO₂ alone accounts for nearly 70% of observed global warming, making it the single most important driver.
  • Long atmospheric lifetime of CO₂ means warming is cumulative and persistent.
• Reduced CO₂ Uptake by Natural Carbon Sinks: Forests, soils, and oceans, which normally absorb nearly half of anthropogenic CO₂ emissions, have shown declining efficiency. Weakened sinks imply more CO₂ remains in the atmosphere, accelerating warming.
  • In 2023, the land carbon sink absorbed almost no CO₂, largely due to: Increased droughts, Intensifying wildfires and Heat stress on vegetation
• Declining Cooling Effect of Aerosols: Aerosols (such as sulphates) reflect sunlight and enhance cloud formation, exerting a temporary cooling effect.
  • Global efforts to improve air quality have reduced aerosol emissions, unintentionally revealing “hidden warming”. Reduced aerosols = less solar radiation reflected back to space.
  • E.g., Regulations by the International Maritime Organization on low-sulphur marine fuels led to a warming of about 0.04°C.
• Exceptionally High Ocean Temperatures: Oceans absorb nearly 90% of excess heat trapped by greenhouse gases.
  • Sea Surface Temperatures (SSTs) remained abnormally high even after El Niño ended in 2024. 
  • Warming was observed beyond the tropical Pacific, indicating: Global-scale ocean heat accumulation and enhanced air–sea heat exchange, warming the atmosphere further
  • Warmer oceans also fuel marine heatwaves, coral bleaching, and extreme weather events.
• Climate Feedback Loops Intensifying Warming: Positive feedback mechanisms amplified warming trends:
  • Droughts → forest fires → more CO₂ emissions
  • Warmer oceans → reduced CO₂ solubility
  • Ice and snow loss → lower albedo → more heat absorption

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