On the heels of a new record high in the Mediterranean, the North Atlantic reached its hottest-ever level this week, several weeks earlier than its usual annual peak.
That is according to preliminary data released yesterday by the US National Oceanic and Atmospheric Administration.
The news comes after scientists confirmed that July is on track to be the warmest month in record history, searing heat intensified by global warming that has affected tens of millions of people.
"Based on our analysis, the record-high average sea surface temperature in the North Atlantic Ocean is 24.9C," or 76.8F, observed on Wednesday, said Xungang Yin, a scientist at NOAA's National Centers for Environmental Information.
The record is particularly startling as it comes early in the year. Usually, the North Atlantic reaches its peak temperature in early September.
The previous record high was recorded in September 2022, at 24.89C, the NOAA said.
The agency, which has been tracking sea temperatures since the early 1980s, will need about two weeks to confirm the preliminary findings.
The Mediterranean Sea reached its highest temperature on record on Monday, Spanish researchers said, amid an exceptional heatwave in Europe.
The record of 28.71C was announced by Spain's Institute of Marine Sciences, which analysed data from satellites used by the European Earth observation programme Copernicus.
Those experts said they measure the daily median sea surface temperature, rather than the average, because it is less susceptible to extreme spikes in temperature in isolated areas of the sea.
The Mediterranean region, hit by record temperatures in July, has long been classified as a hotspot of climate change.
Atlantic record likely to be broken again
The sea surface temperature in the North Atlantic is "expected to continue to increase through the month of August," the NOAA said, adding it was "highly likely" the record would again be broken.
The new high of 24.9C is "more than one degree warmer than a 30-year climatological normal, calculated from 1982 to 2011"m Mr Yin added.
Since March, which is the month when the North Atlantic begins to warm up after winter, temperatures have generally been warmer than in previous years, with the difference more pronounced in recent weeks.
The North Atlantic has become an emblematic observation point for the warming of seawater worldwide due to the effects of climate change caused by greenhouse gas emissions.
The Copernicus programme, which uses different data than that analysed by NOAA, said yesterday that it had recorded a temperature of 24.7C in the North Atlantic.
A Copernicus spokesman said while that remained below the programme's September 2022 record, slightly lower than the NOAA level at 24.81C, that record was sure to be broken "this summer".
"At this stage, it is just a matter of days."
"This situation is extreme: we've seen maritime heatwaves before, but this is very persistent and spread out over a large surface area" in the North Atlantic, said Karina Von Schuckmann from the Mercator Ocean International research centre.
The expert noted that the oceans have absorbed 90% of the excess heat produced by human activity since the dawn of the industrial age.
"This accumulation of energy doubled over the last two decades," fuelling global warming, she said.
On a global scale, the average ocean temperature has been besting seasonal heat records on a regular basis since April.
A specific, striking example has been recorded in Florida where waters off the coast of the Sunshine State reached 38.3C on Monday, according to data from a weather buoy, a temperature more associated with a hot tub.
If confirmed, the reading could constitute a world record.
