Emslie, Michael J., Ceccarelli, Daniela M., Logan, Murray, Blandford, Makeely I., Bray, Peran, Campili, Adriana R., Cantin, Neal, Choukroun, Severine, Cole, Andrew, Jonker, Michael J., Langlais, Clothilde, Puotinen, Marji, Prenzlau, Tara, Sinclair-taylor, Tane H., and Stephenson, Briony (2025) Anthropogenic climate change causes substantial loss of coral on the northern Great Barrier Reef during the 2024 bleaching event. Coral Reefs. (In Press)

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Abstract

The fourth Global Coral Bleaching Event (GCBE) reached the Great Barrier Reef (GBR) in the Austral summer of 2023/24 and caused substantial coral mortality in the Cooktown-Lizard Island sector of the GBR. Thermal stress in this sector ranged from 5.9 to 8.2 °C-weeks (Degree Heating Weeks—DHW) derived from NOAA Coral Reef Watch products, resulting in a 38.6% reduction in sector-wide average coral cover, from 31.2% pre-summer to 19.3% post-summer. Coral loss on individual reefs ranged from 11.4 to 72.2% of pre-summer coral cover levels, with the largest declines on inner and mid-shelf reefs. Despite having among the highest accumulated thermal stress in the study according to NOAA CRW product, the outer shelf reefs experienced little bleaching, and coral cover on these reefs remained largely unchanged. Differential impacts from bleaching across the continental shelf are likely related to localised hydrodynamic factors and community composition, with larger declines on the Acropora-dominated coral assemblages of the inner and mid-shelf reefs than those dominated by Pocillopora on the outer shelf. We provide strong evidence that rapid-growing tabular Acropora spp., the corals responsible for much of the recovery of coral cover across the northern and central GBR between 2017 and 2024, were the most impacted coral taxa. These findings underline the need for urgent action to reduce greenhouse gas emissions and keep global warming to between 1.5 and 2 °C if a future for coral-dominated reefs is to be secured.

Item ID:	91218
Item Type:	Article (Research - C1)
ISSN:	1432-0975
Keywords:	Great Barrier Reef, Thermal stress, Mass coral bleaching, Coral mortality
Copyright Information:	© The Author(s), under exclusive licence to International Coral Reef Society (ICRS) 2025
Date Deposited:	23 Apr 2026 01:55
FoR Codes:	31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 100%
SEO Codes:	18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180504 Marine biodiversity @ 100%
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