After two years of cooling La Niña conditions, the tropical Pacific has undergone one of the fastest transitions ever recorded to a powerful El Niño, raising fresh concerns about global warming, extreme weather events and their impact on agriculture, water resources and food production across the world.
A new climate assessment by Carbon Brief says the developing El Niño has intensified at an unprecedented pace and is now on track to become the strongest event in the modern observational record. The report significantly raises the probability of record global temperatures over the next two years, with 2027 emerging as the most likely candidate to become the hottest year ever recorded.
The analysis shows that after remaining under La Niña influence for nearly two years, the tropical Pacific crossed the El Niño threshold in April 2026 when the Niño3.4 index exceeded 0.5°C. The warming accelerated rapidly thereafter, reaching 1°C in May and 1.6°C in June, already qualifying as a "strong" El Niño. During the first few weeks of July, the index surged beyond 2°C, an intensity that climate scientists classify as a "very strong" or "super" El Niño. This represents one of the fastest intensification rates ever observed, with no previous El Niño event developing at such speed.
Strongest El Niño on record likely
The report is based on an assessment of 667 climate model simulations produced by 14 leading international forecasting systems, including the US Climate Forecast System (CFS), Europe's Copernicus Climate Change Service (C3S), the North American Multi-Model Ensemble (NMME), Canada's CanSIPS and Japan's SINTEX-F.
The median forecast from these models suggests that sea surface temperature anomalies in the Niño3.4 region could peak at 3.59°C between July and December 2026. For comparison, the strongest El Niño on record, the devastating 2015-16 event, reached approximately 2.75°C. Even after adjusting for long-term warming of the tropical oceans using the Relative Oceanic Niño Index (RONI), the median projection remains around 3.1°C, comfortably above the previous record of 2.69°C set during the 1982-83 El Niño.
More importantly, 91% of all model simulations project that this year's event will exceed the previous historical record, while 77% continue to indicate a record event even after correcting for background global warming. Although climate scientists caution that forecasting models occasionally overestimate El Niño strength during spring, forecasts become considerably more reliable after June, lending greater confidence to current projections.
Probability of record-hot 2026 doubles
The rapidly strengthening El Niño has substantially altered expectations for global temperatures in 2026. When Carbon Brief published its previous assessment in April, it estimated only a 19% probability that 2026 would become the warmest year ever recorded. Updated projections now place that probability at 35%, almost double the earlier estimate.
The report projects that 2026 will most likely become the second-warmest year on record, with global average temperatures reaching approximately 1.51°C above pre-industrial levels, narrowly behind 2024.
Scientists estimate there is a 63% probability that average global temperatures during 2026 will exceed 1.5°C above pre-industrial levels. If that happens, 2026 would become only the second calendar year after 2024 to record annual temperatures above the symbolic 1.5°C mark.
However, researchers emphasise that a single year exceeding 1.5°C does not mean the Paris Agreement target has been breached, since that target refers to average warming over a much longer period, generally around two decades.
El Niño is driving forecasts
One of the report's key findings is that the increased likelihood of record temperatures is being driven almost entirely by stronger El Niño forecasts rather than by temperatures already observed this year. Global temperatures during the first half of 2026 averaged around 1.4°C above pre-industrial levels, making it the third-warmest start to any year on record, behind only 2024 and 2025.
January ranked only as the fourth or fifth warmest January because lingering La Niña conditions suppressed temperatures. However, warming accelerated rapidly as El Niño strengthened. May and June both became the second-warmest ever recorded globally.
2027 likely to become hottest year in human history
Scientists say the biggest climate story may not be 2026 at all. Historically, global temperatures respond to El Niño with a lag of around three months because it takes time for the additional heat stored in the Pacific Ocean to spread throughout the atmosphere. Consequently, an El Niño peaking during November and December 2026 is expected to exert its strongest warming influence during 2027.
This pattern was previously observed during the powerful El Niño events of 1997-98, 2015-16, and 2023-24, when the year following El Niño development became significantly warmer than the year in which the event formed.
Using historical relationships between ENSO conditions and annual global temperatures, Carbon Brief projects that 2027 could average around 1.71°C above pre-industrial levels. The analysis assigns a 92% probability that 2027 will become the warmest year ever recorded and a 94% probability that it will exceed 1.5°C above pre-industrial levels. Taking both years together, scientists estimate there is a 93% chance that either 2026 or 2027 will establish a new global temperature record.
Global warming amplifying El Niño impacts
Researchers stress that El Niño itself is a naturally occurring climate phenomenon, characterised by unusually warm sea surface temperatures in the central and eastern tropical Pacific. The phenomenon temporarily transfers enormous amounts of heat from the ocean into the atmosphere, influencing weather patterns worldwide. It often leads to heatwaves, droughts, wildfires and reduced rainfall in some regions while causing excess rainfall and flooding in others.
For India, El Niño has historically been associated with weaker southwest monsoon rainfall, although its influence is modified by several other ocean-atmosphere systems such as the Indian Ocean Dipole and Madden-Julian Oscillation.
Scientists caution that today's El Niño is occurring against the backdrop of long-term human-induced climate change. Carbon Brief notes that the long-term global warming trend has accelerated from around 0.18°C per decade during the early 2000s to nearly 0.27°C per decade today because of continued greenhouse gas emissions. As a result, every strong El Niño now pushes global temperatures onto a much warmer baseline than in previous decades, increasing the likelihood of record-breaking heat.