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

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

Maps published by the organization show that vast areas of the world's oceans were much warmer than the long-term average. The Atlantic was particularly warm, including the sea around the United Kingdom.

The US National Oceanic and Atmospheric Administration (NOAA) has warned that sea temperatures are now so high that the world's coral reefs are facing their fourth known mass bleaching event. (Thomas Moore, more at news.sky.com)