Great Barrier Reef Sees Hottest Waters in 400 Years

Researchers have reported that ocean temperatures in the Great Barrier Reef have reached their highest levels in 400 years, raising alarms about the reef's survival amid ongoing planetary warming. Between 2016 and 2024, the reef, known for its biodiversity, experienced significant coral bleaching events, where elevated water temperatures caused corals to expel essential algae, leading to their potential death. Aerial surveys conducted by the Great Barrier Reef Marine Park Authority revealed that two-thirds of the reef's shallow waters were affected by bleaching. A study published in the journal *Nature* by researchers from Melbourne University and other institutions utilized coral skeleton samples to reconstruct sea surface temperature data from 1618 to 1995. The findings indicated stable temperatures prior to 1900, followed by a steady increase from 1960 to 2024. Notably, the years marked by mass coral bleaching—2016, 2017, 2020, 2022, and 2024—saw temperatures significantly surpassing historical records, with 2004 being the only other comparable year. The implications of these findings extend beyond the reef itself, as coral ecosystems are vital for global seafood production and tourism. Scientists warn that if global warming continues unchecked, 70% to 90% of coral species worldwide could be at risk, leading to a decline in coral diversity. As heat-tolerant species replace more sensitive ones, concerns grow over the long-term health and sustainability of coral reefs, which serve as critical indicators of climate change.