Ocean temperature on the verge of a new record
According to Copernicus' monthly bulletin, the global average ocean surface temperature in March reached 20,97°C, a figure that excludes polar areas to focus on areas where observations are more continuous and comparable over time.
This value is just one-tenth of a degree below the record set in the same month last year, confirming that the ocean continues to accumulate heat very rapidly . Far from being an isolated spike, it follows the last three years, which have been classified as the hottest on record globally.
For Europe, this excess heat stored in the sea is a key underlying factor: the ocean acts as a gigantic energy reservoir that influences air temperatures , the formation of storms, the intensity of rainfall, and the duration of heat waves that affect countries such as Spain, France, Italy, and Portugal.
Transition to a new episode of El Niño
Copernicus warns that recent ocean temperature trends point to a likely transition to El Niño conditions . This natural phenomenon is associated with large-scale warming of the equatorial Pacific waters, with cascading effects on the global climate that extend over several months.
The most recent El Niño event, which occurred between 2023 and 2024, made those two years the warmest ever recorded . With the climate system still reeling from that excess energy, the potential for a similar event to occur again is causing concern within the scientific community.
The World Meteorological Organization (WMO), the leading authority on climate prediction, had already indicated that the opposite phase, La Niña —linked to cooler ocean temperatures—is weakening. In early March, the UN agency estimated a 40% probability of El Niño-like conditions developing before July.
These types of estimates are not a certainty, but they serve as a guide for European and national meteorological services, such as AEMET in Spain, to refine their seasonal projections . If El Niño is confirmed, it could intensify episodes of heat, droughts, or torrential rains in different areas, depending on how the phenomenon interacts with the atmospheric situation over the Atlantic and the Mediterranean.
Impacts of ocean heat: sea level and extreme weather events
The excess heat absorbed by the oceans isn't just a matter of statistics. When water heats up, it expands, directly contributing to sea level rise . This thermal expansion, combined with the water released from melting glaciers and ice sheets, amplifies the risk of coastal flooding.
In the European context, this combination translates into increased pressure on low-lying coastal areas , including densely populated areas of Spain, France, the Netherlands, and Italy. Spring tides, intense storms, and Mediterranean gales are more likely to breach dikes, seafront promenades, and protective systems when the average sea level is higher.
Ocean warming also intensifies marine heatwaves , prolonged periods when water temperatures are significantly higher than usual. These episodes weaken key ecosystems such as coral reefs and kelp forests, and in the Mediterranean, serious impacts on sensitive species have already been detected.
Added to all this is an increase in the intensity of certain extreme weather events, such as more torrential rains and more powerful cyclones in different regions of the planet. Although the exact influence varies by area, recent reports indicate that the warmer ocean provides extra energy to storms, which can lead to episodes of more severe damage and flash floods.
Between land and sea, Copernicus ranks March as the fourth warmest month on record, with an anomaly of around 1,48°C above the pre-industrial average (1850-1900). This historical benchmark is used to assess how far the planet is moving from the temperature targets of the Paris Agreement.
The Arctic is experiencing record lows in sea ice
The Copernicus bulletin doesn't just focus on the state of the oceans; it also confirms that Arctic sea ice extent reached record lows again this winter. The recorded ice area remains at a level similar to last year's record.
These data align with analyses from the NSIDC, a US institute specializing in monitoring polar regions , which had already warned that Arctic ice continues to lose extent and thickness. Less ice means more exposed dark water, which absorbs more solar radiation and warms more rapidly, fueling a vicious cycle of melting and further warming.
The evolution of the Arctic is closely linked to the European climate. Changes in ice distribution and in the temperature contrast between the pole and mid-latitudes can affect atmospheric circulation , altering the trajectory of storms and anticyclones that influence the weather in Spain and the rest of the continent.
In recent years, various studies have linked the weakening of sea ice with a greater frequency of persistent weather patterns , such as prolonged heat waves or periods of almost stationary rainfall, phenomena that have a major economic and social impact in Europe.
The picture painted by Copernicus data—with oceans nearing record temperatures , the risk of El Niño returning, and Arctic sea ice at record lows—points to a climate system under intense pressure. For Spain and Europe as a whole, these signs mean the need to prepare for potentially more extreme summers, more vulnerable coastlines, and more intense weather events, while the scientific community insists that a rapid reduction in emissions is key to preventing these records from becoming the new normal.
