The data from the National Oceanic and Atmospheric Administration (NOAA) has found that the average ocean temperature has been around 21.1C since the beginning of April 2023. This exceeds the highest average temperature that was 21C in 2016. Experts warn that this will lead to an increase in marine heatwaves around the world.

Three consecutive years of La Niña – a weather pattern that carries cold water from the South American coast across the Pacific to Indonesia – has helped to suppress temperatures to an extent but researchers now believe the heat is rising to the ocean surface. This could translate to an El Niño pattern later in the year which is a warm phase that is associated with warm ocean water in the central and east-central equatorial Pacific. Climate experts fear that this could further increase the ocean temperature and the risk of extreme weather and marine storms.

Dr Mike McPhaden, a senior research scientist at Noaa, told The Guardian: “The recent ‘triple dip’ La Niña has come to an end. This prolonged period of cold was tamping down global mean surface temperatures despite the rise of greenhouse gases in the atmosphere.

“Now that it’s over, we are likely seeing the climate change signal coming through loud and clear.”

The data that does not include the polar regions was collected by analysing satellite observations and was verified by measurements from ships and buoys.

The ocean is known to take up over 90% of the additional heat caused by greenhouse gases entering the atmosphere. According to the data, this has led to an astonishing amount of extreme marine heatwaves at the same time. Other studies have shown that these have increased in intensity and frequency over time.

What does this mean for humans and marine ecosystems? Warmer ocean temperatures translate into a higher risk of storms, melting ice sheets, as well as sea level rises. Under the surface, coral bleaching events exacerbate and the food web can be altered, amongst other factors.

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