Australia’s Great Barrier Reef is at a very high risk of extreme and widespread bleaching and “ecosystem collapse” linked to this year’s El Nino weather phenomenon, top scientists warned on July 21.
Often dubbed the world’s largest living structure, the reef stretches 2,300 kilometers along the coast of Queensland state and is a major tourism draw for Australia.
This month it avoided being listed as endangered, despite the United Nations reporting “utmost concern” about mass coral bleaching and the impact of climate change.
Morgan Pratchett, a marine conservation ecologist at Queensland’s James Cook University, told the International Coral Reef Symposium in Auckland, New Zealand, that the “extreme El Nino” posed a significant concern.
“It’s not outside of the realm of possibility that the next major disturbance will lead to localized species extinctions and widespread ecosystem collapse,” Pratchett said.
This year’s El Nino is expected to break records for its overall strength as it warms surface temperatures in the central and eastern equatorial Pacific Ocean, bringing worldwide changes in winds, pressure and rainfall patterns.
“It’s a very high likelihood that we’ll see very high severity and large-scale mass bleaching on the Great Barrier Reef,” Pratchett said.
UNESCO has been monitoring the reef annually since 2021, when it warned it was at risk of being placed on the list of World Heritage items “in danger.”
Hard coral cover across the reef declined substantially in 2024-2025, with above-average water temperatures causing the reef’s sixth mass coral bleaching event since 2016.
