PARIS, France (AFP) — Leading European climate researchers have issued an updated alert that global ocean surface temperatures are rapidly approaching all-time record levels, as early indicators confirm the climate system is shifting toward an impending El Nino event that could push global heat to unprecedented new heights.
Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasts (ECMWF), which manages the European Union’s Copernicus Climate Change Service, confirmed that recent sea surface temperature (SST) readings are already just a fraction below the 2024 record, the hottest year documented to date. She projects that the monthly global average for May is on track to break its own existing temperature record, and it will likely only take a matter of days before daily SST readings return to uncharted record territory.
Copernicus’ April climate bulletin shows that daily ocean temperatures “gradually inched” toward near-record levels through last month, a clear signal of the ongoing transition into El Nino conditions that forecasters predict will solidify in the coming months. April’s overall global ocean temperature ranked as the second-warmest ever measured, with record-breaking marine heatwaves already stretching across the swathe of ocean from the tropical Pacific to the western coast of the United States.
The World Meteorological Organization previously projected that El Nino conditions could develop as early as the May-to-July window this year. A naturally occurring phase of the Pacific Ocean’s climate cycle driven by shifts in sea surface temperatures and trade winds, El Nino reshapes weather patterns across the globe, raising the probability of extreme events including severe droughts, intense heavy rainfall and other disruptive climate disasters.
Crucially, El Nino adds extra atmospheric heat to a planet already warmed to dangerous levels by centuries of fossil fuel combustion. The most recent El Nino event was a key factor that pushed 2023 to become the second-hottest year on record, followed by 2024 which claimed the top spot as the warmest year ever measured. Multiple weather agencies have forecast that the upcoming El Nino could be unusually strong, potentially matching the intensity of the powerful “super El Nino” that occurred three decades ago.
Zeke Hausfather, a climate scientist with independent research group Berkeley Earth, noted last week that a strong El Nino would substantially boost the odds that 2027 will overtake 2024 to become the hottest year recorded in human history. Burgess emphasized that it remains too early to definitively predict the coming event’s intensity, as seasonal forecasts produced during Northern Hemisphere spring are often less reliable than those made at other times of year. That said, she added that no matter how strong the event proves to be, its impacts will be impossible to ignore.
“We’re likely to see 2027 exceed 2024 for the warmest year on record,” Burgess stated, explaining that El Nino’s maximum impact on global annual temperatures typically arrives in the calendar year after the event reaches its peak intensity.
Copernicus’ analysis confirms that the rise in ocean temperatures across March and April confirms the shift from neutral ENSO (El Nino-Southern Oscillation) conditions to El Nino is already underway. Climate researchers stress that El Nino alone is not the root cause of the extraordinary ocean warming and its harmful knock-on effects, which include mass coral bleaching and widespread persistent marine heatwaves.
The current El Nino transition is unfolding against the long-term backdrop of human-caused global warming driven by rising greenhouse gas emissions. Earth’s oceans have absorbed roughly 90 percent of the excess heat trapped by human activity, making marine warming one of the clearest measurable indicators of ongoing climate change.
Alongside ocean warming, Copernicus reported that April 2025 ranked as the third-hottest April for global land and ocean surface temperatures combined, coming in 1.43 degrees Celsius above the pre-industrial baseline average measured between 1850 and 1900 — a threshold widely used to track progress toward global climate targets. Arctic sea ice extent remained near record lows for the month of April, while variable seasonal conditions across Europe have set the stage for a hotter, drier than average summer with elevated risk of drought and wildfire.
“We just keep seeing extremes. Every month we have more data that the climate change impact is creating these extreme events,” Burgess said.