Marine heatwaves are killing coral reefs far more quickly than previously believed, according to a new study released yesterday. Scientists have known that rising sea temperatures blamed on global warming can severely damage reefs through a process of “bleaching,” where the high temperatures kill the colourful algae covering and nourishing coral.

Repeated “bleaching events”, such as ones which hit Australia’s Great Barrier Reef in 2016 and 2017, can eventually kill the coral in a process which takes months or years. If sea temperatures ease, bleached corals are able to regenerate.

But the new study found that severe marine heatwaves can actually degrade the skeletal structure of the coral, potentially killing the organisms in a matter of days or weeks.

“The severity of these heatwave events is beyond the bleaching process, it’s actually a point where the coral animal itself is dying,” said Tracy Ainsworth, a co-author of the study from the University of New South Wales.