Great Barrier Reef suffering 6th mass-bleaching

Australia's Great Barrier Reef is suffering its sixth mass bleaching event due to heat waves caused by climate change, scientists said Friday.

Driving the news: At least 750 reefs show widespread bleaching, the Great Barrier Reef Marine Park Authority (GBRMPA) and Australian Institute of Marine Science (AIMS) said.

• “When we categorize a reef as severely bleached from aerial surveys, what we're seeing is more than half of the living coral cover that we can see from the air is severely bleached completely white and can have signs of fluorescence in the colors of pink, yellow and blue,” AIMS coral biologist Neal Cantin said.
• Researchers noted bleaching caused by intense sun from marine heat waves was most severe through central and northern sectors of the marine park.

Why it matters: The announcement comes as the UN Educational, Scientific and Cultural Organization (UNESCO) conducts a 10-day monitoring mission to decide whether to add the reefs to its "in danger" list.

• If declared an "in danger" area, it would become the first World Heritage-listed site designated as such due to the climate crisis, the Guardian reported.

The big picture: The Great Barrier Reef, one of the world's seven natural wonders, has lost half of its corals in the past quarter-century.

• "The consequences of these changes are not just environmental," UNESCO also said in an editorial. "Nearly three billion people depend directly on marine and coastal biodiversity for their survival. By 2050, coastal areas that are home to 300 million people could be threatened by rising sea levels due to climate change."
• Globally, coral has declined by 14% primarily due to large-scale bleaching events.

While it's not yet clear as to the exact extent of the damage, repeat bleaching events with little recovery time severely endanger a reef's ecosystem and reduce its chances to thrive, experts said.

• "After a 14yr reprieve, bleaching in 2016 killed billions of corals on the GBR reducing cover by 30%" Australian reef scientist Terry Hughes tweeted on Friday evening, citing graphs from a 2020 Intergovernmental Panel on Climate Change report.
• "Since 2016, mass bleaching has occurred again in 2017, 2020 and 2022. You will not see a 14yr gap again in your lifetime."

The other side: In 2021, Australia rejected UNESCO's "in-danger" assessment, saying it would "strongly oppose" the recommendation.

• "The Great Barrier Reef is the best managed reef in the world and this draft recommendation has been made without examining the Reef first hand, and without the latest information," Australia's Environment Minister Sussan Ley said in a statement.

Axios' Andrew Freedman contributed to reporting.