Global sea surface temperatures have reached record highs for this time of year, with European Union climate monitors warning the trend could fuel sea level rises and more extreme weather on land.

New data released by the European Union’s Copernicus Climate Change Service and Copernicus Marine Service on Tuesday put the global average sea surface temperature at 21 degrees Celsius on Jun 21.

That beat the previous records of 20.83 degrees Celsius in 2023 and 20.86 degrees Celsius in 2024, according to the monitoring agencies.

Scientists said the latest reading marked another sign that the world’s oceans are moving into what they described as “uncharted territory”.

The monitors said the onset of El Niño in the equatorial Pacific on Jun 2 had contributed to the rise, but added that it is part of a longer-term warming trend driven by climate change.

According to Copernicus, ocean temperatures outside polar regions have been between 0.35 degrees Celsius and 0.73 degrees Celsius above the long-term average over the past three years.

Carlo Buontempo, director of the Copernicus Climate Change Service at the European Centre for Medium-Range Weather Forecasts, said current conditions could mark the beginning of a new phase of warming.

He warned that ocean temperatures at these levels, combined with El Niño on the horizon, are likely to push more records in the coming months.

The report follows recent United Nations projections that put the chance at 91 percent that at least one of the next five years will cross the one point five degrees Celsius warming threshold set under the Paris Agreement.

The UN also said there is an 86 percent chance one of those years will surpass 2024 as the hottest year on record.

Scientists warned warmer oceans can add energy to storms, increase evaporation and raise the risk of flooding through heavier rainfall.

They said rising sea temperatures also contribute to sea level rise, ice melt and marine heatwaves that damage ecosystems, fisheries and coastal economies.

Climate scientist Friederike Otto of Imperial College London warned that any prolonged period above one point five degrees Celsius could trigger extreme weather beyond anything experienced before.

Copernicus scientists said they are continuing to monitor whether the latest temperature spike is temporary or part of a longer-lasting shift.