'Unprecedented Mass Coral Bleaching' Expected in 2024, Says Expert

Record-breaking land and sea temperatures, driven by climate breakdown, will probably cause "unprecedented mass coral bleaching and mortality" throughout 2024, according to a pioneering coral scientist. From a report: The impact of climate change on coral reefs has reached "uncharted territory," said Prof Ove Hoegh-Guldberg, from the University of Queensland, Australia, leading to concerns that we could be at a "tipping point." The upper ocean is undergoing unmatched changes in conditions, ecosystems and communities that can be traced back to the 1980s, when mass coral bleaching first appeared. In a paper published in the journal Science, US and Australian researchers say that historical data on sea surface temperatures, over four decades, suggests that this year's extreme marine heatwaves may be a precursor to a mass bleaching and coral mortality event across the Indo-Pacific in 2024-25. Mass coral bleaching happens when delicate corals become stressed due to factors including heat, causing them to lose their brown microbial algae, turning them white. At low stress levels, the algae can return to corals over a few months. But many Caribbean reef areas have recently experienced historically high sea temperatures that began one or two months earlier and lasted longer than usual. Crucially, 2023 is the first year of a potential pair of El Nino years, with the warmest average global surface sea temperature from February to July on record. Since 1997, every instance of these El Nino pairs has led to a global mass coral bleaching event.

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