The world’s oceans are heating up. Record after record is being broken. This time, the average sea surface temperature of the world, excluding the polar regions, has risen to 21.1 degrees Celsius. This is the highest temperature ever recorded.
Most worryingly, this record-breaking event comes at a time when the already strong El Niño has not yet reached its peak. Scientists fear that if El Niño becomes stronger, sea temperatures could rise further.
According to the European Union’s Copernicus Climate Change Service, the average sea temperature reached 21.1 degrees Celsius on Saturday. The previous record of 21.09 degrees Celsius was recorded for three days in March 2024. This time, that record has been slightly exceeded.
The temperature difference is not very large. There is some uncertainty in the global figures. But the timing of the record-breaking is a big concern for scientists.
The average global sea surface temperature is usually highest in March or April, the end of summer in the Southern Hemisphere. However, this time, that record was broken in August.
The Southern Hemisphere has a higher sea level, which means it has a greater influence on global average sea temperatures.
Samantha Burgess, deputy director of Copernicus, said this record is another clear signal of the increasing pressure on the oceans.
According to him, El Niño is currently adding extra heat to the ocean system, but its foundation is built on decades of warming caused by human activities.
El Nino has not yet peaked.
El Niño is a natural weather phenomenon that occurs when unusually warm water rises to the surface in the central and eastern equatorial Pacific Ocean. When ocean waters warm over a large area, global average temperatures usually rise.
Scientists say El Nino could strengthen by Christmas, warning that it is on track to become the strongest El Nino in centuries.
Jeremy Grist, a senior researcher at the National Oceanography Center, said that breaking sea temperature records before El Niño reaches its peak strength is an early indication of its increasing strength.
He believes that if conditions remain unchanged, the sea temperature record could be broken again in March or April 2027.
Long heatwave in Europe’s seas
Not only distant oceans, but also the seas around the UK and Europe have become unusually warm.
Tim Smythe, science director at Plymouth Marine Laboratory, said the western English Channel has been experiencing a near-continuous marine heatwave for more than three years, with water temperatures there in July being around 7 degrees Celsius above normal.
In Smythe’s words, this is unprecedented.
The risk of storms, floods and marine life is increasing
The impact of this unusually warm ocean will not be limited to the water. The warm ocean adds extra moisture and strength to storms, which could make extreme weather events more intense.
Warmer seas can also increase land heat waves in some coastal areas, because warm sea air cannot cool the coast as much as before.
Another major threat is sea level rise. Warmer water takes up more space, causing sea levels to rise and increasing the risk of coastal flooding.
It could also have a major impact on marine animals and ecosystems. Various marine habitats, including coral reefs, could be severely damaged by excessive heat.
The ocean absorbs more than 90 percent of the excess heat trapped by human greenhouse gas emissions, the main source of which is the burning of fossil fuels.
Burgess said the increasing trend of marine heatwaves is placing increasing pressure on marine ecosystems and the people who depend on them.
This new ocean temperature record is not just a new number. Scientists believe it is another major warning sign of how quickly the Earth’s climate system is warming.
