Record warmth has changed the meaning of a possible El Niño year
Scientists worry about a new El Niño because it would arrive in a climate system already running hot. WMO confirmed that 2024 was the warmest year in the 175-year observational record. The agency put the annual temperature at 1.55°C above the 1850 to 1900 average. WMO then confirmed that 2025 ranked among the three warmest years ever recorded. That result matters because 2025 stayed near the top even with La Niña offering some temporary cooling. The broader trend, therefore, remained powerful. Ocean heat also stayed high, and long-term warming did not pause. WMO said the past 11 years were the 11 warmest on record. That statement shows why scientists now view each natural climate swing through a different lens. El Niño still adds heat through a familiar ocean-atmosphere process.
Yet it now does so on top of a far warmer baseline. A future event does not need to become historic on its own terms to help produce historic outcomes. It can amplify extremes that were already building. It can also stretch warm conditions across seasons that once had more room for fluctuation. That is why current forecast discussions carry more weight than similar outlooks might have carried decades ago. A warming Pacific no longer enters a neutral background. It enters a climate system that has already lost much of its old margin. Even modest extra warming can therefore have larger consequences than it once did. That change helps explain the sharper tone in current scientific discussions. WMO’s climate assessment adds important timing and context to that concern.
It says 2024’s global mean temperature was boosted by a strong El Niño that peaked early in the year. Yet it also says temperatures were already at record levels in 2023. In every month from June 2023 through December 2024, monthly global temperatures exceeded all earlier records for those months. WMO also stresses a point that often gets blurred in public debate. A single year above 1.5°C does not mean the Paris Agreement limit has been permanently breached. That target is measured over decades, not one calendar year. Even so, the practical risk remains serious. When the world starts from such an elevated baseline, extra Pacific warming can tilt several systems at once.
It can influence temperature records, marine heat, glacier melt, crop stress, and public health burdens. Secretary-General Celeste Saulo said the 2023 to 2024 El Niño “played a role” in record temperatures. She also warned that human-driven warming remains the deeper force behind the trend. Scientists, therefore, watch for more than a temperature headline. They look at how El Niño can interact with hot oceans, warm land, and already stressed systems. In that setting, even a merely strong event could produce outsized consequences. The forecast debate is therefore not about hype alone. It is about what added Pacific warming could mean in a climate era that already keeps breaking expectations. It is also about timing, because a late-year warming pulse can influence the following season.