In 1998, a mysterious phenomenon turned many of the world’s most colourful coral reefs deathly white.

It was the first recorded global coral bleaching event in history, and ecologists blamed it on rising ocean temperatures caused by climate change.

Studies showed that when the oceans get warmer, it stresses the corals, causing them to expel the algae that give them their colour, and so turn white.

Since then there have been four global bleaching events, which have destroyed up to 20% of the world’s reefs, and threatened the economy, tourism and livelihoods of more than 30 countries.

Marine ecologist Clive Wilkinson worked as co-ordinator for the Global Coral Reef Monitoring Network, based in Queensland, Australia. He tells Jane Wilkinson how the first reports of the phenomenon caused shockwaves in 1998.

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(Photo: Reef in Trat, Thailand, damaged by coral bleaching. Credit: Sirachai Arunrugstichai/Getty Images)