https://news.sky.com/story/climate-change-worlds-oceans-reach-highest-temperature-on-record-13088540

The world's oceans have reached their highest temperature on record, raising fears that coral reefs are on the brink of a massive and potentially lethal heat shock.

New satellite data from the European Copernicus Climate Change Service shows the global average sea surface temperature in February was 21.06C, higher than the previous record of 20.98C set in August last year.

Maps released by the organisation show huge areas of the world's oceans were much warmer than the long-term average. The Atlantic was particularly warm, including the sea around the UK.

The US National Oceanic and Atmospheric Administration (NOAA) has warned sea temperatures are now so high that the world's coral reefs face their fourth known mass bleaching event.

Heat stress can cause corals to expel the colourful algae living in their tissues. Without the algae they turn bleached white and are vulnerable to disease and starvation, and eventually die-off.

Derek Manzello, the coordinator of NOAA's Coral Reef Watch told the Reuters news agency: "It's looking like the entirety of the Southern Hemisphere is probably going to bleach this year.

"We are literally sitting on the cusp of the worst bleaching event in the history of the planet."