Coral reefs set to stop growing as climate warms
University of Exeter
image:
Dead reef crest on Mexico's Caribbean coast
view moreCredit: Chris Perry
Most coral reefs will soon stop growing and may begin to erode – and almost all will do so if global warming hits 2°C, according to a new study in the western Atlantic.
An international team, led by scientists from the University of Exeter, assessed 400 reef sites around Florida, Mexico and Bonaire.
The study, published in the journal Nature, projects that more than 70% of the region’s reefs will stop growing by 2040 – and over 99% will do so by 2100 if warming reaches 2°C or more above pre-industrial levels.
Climate change – along with other issues such as coral disease and deteriorating water quality – reduces overall reef growth by killing corals and impacting colony growth rates.
To understand how changing reef ecology is impacting reef growth potential – in other words, how the balance of living organisms translates into vertical “accretion” (reef-building) – the team analysed fossil reefs from across the tropical western Atlantic region to improve understanding of how reef growth rates vary depending on the types of coral present.
They then combined this with ecological data from more than 400 modern reef sites across the region to calculate present-day reef growth rates, and to explore how growth rates will change under future climate change, and whether reefs can keep up with future sea-level rise.
“Our research shows that under current CO2 emission scenarios most Atlantic coral reefs will not only stop growing but many will actually be eroding by mid-century,” said lead author Professor Chris Perry, of the University of Exeter.
“At the same time, rates of sea-level rise will increase – and our analysis suggests the growth of reefs will lag behind.
“With reefs and sea levels moving in opposite directions, water depths above reefs will increase – raising flooding risks along vulnerable reef-fronted coasts and fundamentally changing nearshore ecosystems.
“Resultant water depth increases of around 0.7m are projected by the end of this century if global temperature increases exceed 2°C, and as much as 1.2m under higher warming rates.”
Reef growth is strongly influenced by the amount and types of living coral present.
Multiple factors including disease outbreaks and “bleaching” events caused by high temperatures have changed the makeup of many reefs – depleting key reef-building species.
“We are witnessing an alarming decline in both the abundance and diversity of corals across Atlantic coral reefs,” said co-author Dr Lorenzo Alvarez-Filip, from the Universidad Nacional Autonoma de México.
“Climate change is not only accelerating this decline but also worsening the cascading ecological and socio-economic consequences of their loss.”
Co-author Dr Didier de Bakker, from the University of Exeter, said: “The changes we project would have major impacts along coastlines where reefs presently help limit wave exposure.
“These changes would also transform the environmental conditions in nearshore lagoons which harbour important habitats such as seagrass beds.”
One strategy to reverse losses and enhance reef growth is coral restoration.
Dr Alice Webb, also from the University of Exeter, said: “The scale of action required to reverse current coral losses is significant.
“To have meaningful effects on limiting water depth increases, any restoration will need to occur in tandem with effective land and water management, and rapid climate mitigation actions. Actions to keep warming below 2°C are critical.”
Professor Perry concluded: “We are moving into a period where the two factors that control water depths above coral reefs – vertical reef growth rate and sea level rise rate – are starting to operate in increasingly divergent directions.
“Limiting climate warming is critical if we are to try to mitigate this and to avoid the worst impacts for coastlines and coastal ecosystems.”
The paper is entitled: “Reduced Atlantic reef growth past 2°C warming amplifies sea-level impacts.”
Widespread bleaching - Mexican Caribbean, 2023
Credit
Lorenzo Alvarez-Filip
Journal
Nature
Article Title
Reduced Atlantic reef growth past 2°C warming amplifies sea-level impacts.”
Article Publication Date
17-Sep-2025
Gulf of Aqaba corals survive record-breaking heatwaves, offering hope amid global coral crisis
image:
Coral Reef
view moreCredit: Maoz Fine
New study reveals that corals in the Gulf of Aqaba have withstood four consecutive and intensifying marine heatwaves, including the world’s most extreme 2024 event, without suffering mass bleaching — a resilience unmatched elsewhere. This is important because coral reefs globally are collapsing under rising ocean temperatures, threatening ecosystems and human livelihoods. The Gulf of Aqaba may represent one of the planet’s last natural refuges for reef survival, offering a crucial model for understanding resilience and underscoring the urgency of protecting this unique ecosystem before even it reaches its limits. New study reveals resilience of Red Sea corals in the face of intensifying climate threats.
Coral Reef: https://drive.google.com/drive/folders/1nvggt4ffICAkBiIC6ZCqG_trTvRm306Y
Credit: Maoz Fine
[Hebrew University] — A new study led by Phd. student Na'ama-Rose Kochman and Prof. Maoz Fine of the Hebrew University’s Institute of Life Sciences and the Interuniversity Institute for Marine Sciences in Eilat, has uncovered extraordinary resilience among corals in the Gulf of Aqaba (GoA), raising hopes for the future of this globally-significant coral reef amid worsening climate change.
The findings, published in Science of the Total Environment, show that GoA corals endured four consecutive summers of intensifying marine heatwaves, including a record-breaking 2024 event that lasted 113 days with sea surface temperatures soaring to 32.6°C — 3.4°C above average and generating 30 Degree Heating Weeks (DHWs), the highest thermal stress recorded globally last year.
Key Findings
- Survival through record stress: Five coral species survived the world’s most extreme 2024 heat event without mass bleaching.
- Energy resilience: Corals maintained stable energy reserves, with higher symbiont carbohydrates in 2024 compared to previous years.
- Species responses: Porites showed metabolic stability, while Cyphastrea experienced stress but recovered within months.
- A climate refuge under pressure: Despite remarkable tolerance, sporadic shallow bleaching suggest the Gulf’s may be reaching its limit.
“While nearly half of reef-building corals worldwide face the risk of extinction, our study shows that the Gulf of Aqaba remains one of the last strongholds of reef survival,” said Na'ama-Rose Kochman. “But even this refuge is not immune to the accelerating pace of climate change and local pollution.”
Prof. Fine added: “These results highlight both the resilience and the fragility of coral ecosystems. They underscore the urgent need for regional conservation policies to safeguard what could be the world’s last thriving coral reef.”
Coral reefs are biodiversity hotspots that sustain millions of livelihoods, from fisheries to coastal protection. Yet marine heatwaves — prolonged periods of unusually warm sea surface temperatures — are now one of the primary drivers of coral mortality worldwide.
The resilience of the Gulf of Aqaba corals offers a rare glimmer of hope. Scientists emphasize, however, that without rapid climate action and local protections, even this stronghold may not withstand future warming.
Coral Reef
Credit
Maoz Fine
Journal
The Science of The Total Environment
Method of Research
Observational study
Subject of Research
Animals
Article Title
Gulf of Aqaba as a thermal refuge: Insights from four years of intensifying marine heatwaves
Article Publication Date
16-Sep-2025
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