Standard Presentation (12 minutes) Australian Marine Sciences Association 2025 Conference

The 4th Global Coral Bleaching Event (GCBE4): 2023- ? (120054)

Blake L Spady 1 2 3 , William Skirving 4 , Jacqueline De La Cour 5 , Erick F Geiger 2 6 , Gang Liu 6 , Andrew Norrie 4 , Scott F Heron 3 , Derek P Manzello 6
  1. NOAA Coral Reef Watch, Mundingburra, QUEENSLAND, Australia
  2. Global Science and Technology, Greenbelt, Maryland, United States
  3. James Cook University, Townsville, Queensland, Australia
  4. ReefSense, Townsville, QLD, Australia
  5. CISESS, College Park, Maryland, United States
  6. NOAA Coral Reef Watch, College Park, Maryland, United States

On April 15, NOAA announced the presence of the 4th Global Coral Bleaching Event (GCBE4). Since February 2023, mass coral bleaching has been documented across at least 75 different countries/territories spanning the northern and southern hemispheres of all ocean basins. GCBE4 has been record-setting, as more than 3/4 of the world’s reef area has experienced bleaching-level heat stress, exceeding the previous record set during the 3rd Global Coral Bleaching Event (GCBE3; 65.7%). Coral reef areas in both the northern and southern Atlantic Ocean have experienced the most extreme levels of heat stress during this event, with Degree Heating Week (DHW, ºC-weeks) values 2-3 times greater than previous records. The majority of reef areas in the wider Caribbean and south Atlantic exceeded 16 ºC-weeks, with some regions surpassing 20 ºC-weeks. Between 19 May 2023 and 18 May 2024, 99.9% of all reef area in the Atlantic Ocean experienced bleaching level-heat stress. Record-setting heat stress has also occurred throughout the Pacific and Indian oceans. This presentation will provide updates on the latest trends and patterns of this ongoing, record-setting marine heatwave, and some details of the known impacts so far.