The consequences of 2023, the hottest year measured since records began, are already visible on corals, one of the riches of nature most threatened by human-caused climate change. Although it is still impossible to measure actual mortality in polyp colonies, the process is ongoing, marine heat waves have brought many of the planet’s reefs into a lethal zone. Monday April 15, the National Oceanic and Atmospheric Administration (NOAA) thus confirmed that the Earth “experiences a new global coral bleaching event”.
According to scientists from the American agency who compiled observations from many regions and records of sea surface temperatures (Sea Surface Temperature, SST) between February 2023 and April 2024, this episode, the fourth since the beginning of surveys in 1985, the second in less than ten years, is ” important “. “It is still premature to assess the impacts, but it seems very powerful, especially since it occurs very quickly after that of 2016 when the corals need several years, sometimes ten years to regenerate when they are not. don’t die”, estimates Jean-Pierre Gattuso, oceanographer (CNRS) at the Villefranche Oceanography Laboratory (Alpes-Maritimes). In 2018, a study published in the journal Nature revealed that the heat of 2016 caused the death of 30% of the corals of the Australian Great Barrier Reef.
This time again, the overall phenomenon is impressive. According to NOAA, it affects Florida in the United States, the Caribbean Sea, Brazil, the eastern Pacific along Mexico, large areas of the South Pacific (including French Polynesia), the Red Sea, the Persian Gulf and the Gulf of Aden, the Seychelles, Mayotte, the west coast of Indonesia but also the Great Barrier Reef. On March 8, the Australian authorities had already announced that, for the seventh time in twenty-six years, a “mass bleaching” hit the largest living structure in the world. The fifth episode in eight years in this zone.
“As the world’s oceans continue to warm, coral bleaching is becoming more frequent and severewarns Derek Manzello, coordinator of the collection of this data, in the NOAA publication. When these events are intense and prolonged, they can cause coral mortality. »
“Serious consequences”
You have 65.91% of this article left to read. The rest is reserved for subscribers.
