Ocean temperatures reach unprecedented high, climate scientists warn

The Earth’s oceans have reached an all-time high temperature, according to preliminary data from the National Oceanic and Atmospheric Administration (Noaa). The average temperature at the ocean’s surface has been recorded at 21.1C since the start of April, surpassing the previous high of 21C set in 2016.

Climate scientists are ringing alarm bells, warning that the current trajectory is headed off the charts, smashing previous records. The record-breaking temperatures follow three years of La Niña conditions in the tropical Pacific, which have had a cooling effect on global temperatures.

However, scientists believe that the recent end of La Niña has allowed the climate change signal to come through loud and clear. The data shows that the ocean’s surface temperature is rising, pointing to a potential El Niño pattern in the tropical Pacific later this year. El Niño events are known to push up global temperatures and challenge record highs.

Professor Matthew England, a climate scientist at the University of New South Wales, described the current situation as “the emergence of a warming signal that more clearly reveals the footprint of our increased interference with the climate system.” He warned that the record-breaking temperatures are not just a passing phenomenon, but a harbinger of a worsening climate crisis.

The record-breaking temperatures are driven mostly by satellite observations, but are also verified with measurements from ships and buoys. The data does not include the polar regions, where temperatures have been declining. More than 90% of the extra heat caused by greenhouse gas emissions has been taken up by the ocean, accelerating and penetrating deeper, providing fuel for extreme weather events.

Sea surface temperatures are not the only concern. Measurements from the top 2km of the ocean show the rapid accumulation of heat in the upper parts of the ocean, particularly since the 1980s. This heat is extending down to over 100 metres, having knock-on effects for the atmosphere above, creating more heat, adding energy to weather systems, and causing marine heatwaves.

Associate Professor Alex Sen Gupta, an expert on marine heatwaves, said it is unusual to see so many extreme events all at the same time. He warned that the current situation is a warning sign, pointing to a trend of increasing frequency and intensity of marine heatwaves as the oceans warm.

The consequences of the record-breaking temperatures are far-reaching, including increased energy for storms, the melting of ice sheets, and higher global sea levels. Marine heatwaves can also have devastating effects on marine wildlife and cause coral bleaching on tropical reefs.

As the planet’s most important stories, the current situation serves as a stark reminder of the urgent need for climate action. Climate scientists are warning that the signal of human-caused global heating is clear, and that the consequences of inaction will be severe.