Oceans reach record July heat as El Niño amplifies climate extremes

In a development that has underscored the profound shifts occurring within the planetary climate system, the world’s oceans registered their highest average surface temperatures for any July on record last month, a milestone attributed in part to the strengthening of El Niño conditions across the Pacific, according to data released by the European Union’s Copernicus Climate Change Service. The average sea surface temperature, measured between the latitudes of 60 degrees north and 60 degrees south to exclude the polar regions, reached 20.96C in July, marginally exceeding the previous benchmark of 20.89C set in 2023, while the month itself was deemed the joint second-warmest July globally, with temperatures running 1.47C above the estimated pre-industrial mean. This oceanic heat has been accompanied by an exceptional run of extreme weather on land, particularly across western Europe, which experienced its hottest combined June and July since records began, with prolonged hot and dry conditions precipitating widespread wildfires and placing considerable strain on water resources, even as the United Kingdom prepares for its fifth heatwave of the year and the potential for further official drought declarations.

The Copernicus service, which monitors climatic variables with a focus on long-term trends, noted that July’s sea surface temperatures were notably high along the Atlantic seaboard and throughout the western Mediterranean basin, contributing to what it described as widespread and severe marine heatwaves in those regions. Concurrently, much of the tropical Pacific exhibited exceptionally high sea temperatures, a signature of the developing El Niño pattern, which is forecast to gather strength in the coming months and which, when superimposed upon the long-term warming trend driven by anthropogenic greenhouse gas emissions, has the capacity to produce significant temperature spikes and an increased incidence of extreme meteorological events. Oceans, which function as a critical regulator of the Earth’s climate by absorbing the majority of excess heat generated by human activity and producing roughly half of the planet’s oxygen supply, are becoming less efficient carbon sinks as their temperatures rise, with warmer waters absorbing diminished quantities of carbon dioxide and thereby leaving a greater proportion of this potent greenhouse gas to accumulate in the atmosphere, a feedback loop that carries serious implications for the rate of future warming.

Highlighting the direct consequences of these elevated temperatures, Copernicus reported that western Europe endured an average temperature of 21.62C across June and July, a figure that stands 2.79C above the seasonal norm and represents the highest ever recorded for that two-month period in the region. Samantha Burgess, the strategic lead for climate at the European Centre for Medium-Range Weather Forecasts, observed that July 2026 marked the third consecutive month of exceptional heat in western Europe, a trend driven by persistent high-pressure systems that have trapped warm air over the continent and exacerbated by dry soils that have lost their capacity to provide natural cooling through evaporation, offering what she characterised as a clear example of how climate change is intensifying heat extremes, with heat and drought conditions increasingly reinforcing one another in a dangerous synergy. This combination of factors has produced remarkably low rainfall and soil moisture levels across France, Spain, parts of Germany, and the United Kingdom, with soil aridity in much of western Europe now significantly exceeding that observed in 2022, the year of the region’s previous severe drought, a situation that has been mirrored in river levels, with major waterways such as the Seine, Rhine, and Danube recording flows that are much lower than average and, in certain locations, exceptionally so.

These depleted watercourses have, in turn, intensified pressure on water supplies for domestic and agricultural use, irrigation systems, aquatic ecosystems, river transport, and energy production, particularly hydroelectric power generation. The persistently hot and arid conditions have also created tinderbox environments conducive to the outbreak and spread of wildfires, with last month witnessing massive blazes across western Europe and what Copernicus described as “exceptional activity” in terms of the total area burned and the volume of smoke and emissions generated. Laurence Rouil, the director of the Copernicus Atmosphere Monitoring Service, warned that climate change is increasingly producing the hot and dry conditions that favour large, high-intensity wildfires in southern Europe, while simultaneously extending the traditional fire season northwards, and noted that larger fires tend to produce more smoke and inject it to higher altitudes, enabling it to travel over much greater distances and potentially affecting countries that have historically experienced relatively few wildfires with smoke-borne pollution.

In the United Kingdom, the sustained dry spell has placed further strain on water supplies that were already under considerable stress, with the Met Office confirming that England and Wales experienced their driest July in 190 years of record-keeping, while large parts of England and the entirety of Wales have already been formally declared to be in drought. The Environment Agency has indicated that additional areas of England may be subject to similar declarations should the current dry conditions persist, a prospect that appears increasingly likely given the prevailing meteorological patterns. According to the latest assessment from the Met Office on the state of the UK’s climate, weather that was once considered extreme is becoming the “new normal”, with the hottest day of the year in southern England now registering 4.5C warmer than the equivalent figure for the period between 1961 and 1990, a shift that Mike Kendon, a climate information scientist at the Met Office, described as evidence that the climate of the 20th century has effectively disappeared, with the present era representing a time of historic and unprecedented change.

Scientists have emphasised that the effects of the current El Niño event, which may temporarily push global temperatures even higher, are being felt against a persistent backdrop of human-induced warming, predominantly driven by the combustion of fossil fuels, which has raised the world’s average temperature by approximately 1.4C since the late 19th century. The confluence of these natural and anthropogenic factors has resulted in a situation where ocean heat content, terrestrial temperature extremes, and hydrological disruptions are converging to create a series of interconnected environmental challenges that span continents and demand a comprehensive and coordinated response, even as the immediate focus remains on the tangible impacts of the heatwaves, droughts, and wildfires that have come to characterise the summer months in many parts of the globe.