A rapidly closing window for coral persistence under global warming.

Area of Science:

• Marine biology
• Climate change science
• Ecological modeling

Background:

• Coral reefs face existential threats from marine heatwaves, leading to bleaching and mortality.
• Understanding coral adaptation and refugia is critical for effective reef management and persistence.
• Global climate projections indicate severe impacts on coral ecosystems worldwide.

Purpose of the Study:

• To simulate coral eco-evolutionary dynamics on the Great Barrier Reef under various climate scenarios.
• To forecast coral reef decline and recovery potential based on thermal adaptation and refugia.
• To inform strategic management decisions for coral persistence in the face of climate change.

Main Methods:

• Eco-evolutionary dynamics simulations across 3800 Great Barrier Reef sites.
• Analysis of coral responses to projected marine heatwaves and warming trajectories.
• Assessment of thermal adaptation capacity and the role of bleaching refugia.

Main Results:

• Projected rapid coral decline by mid-century across all emission scenarios.
• Potential for reef recovery this century if global warming is limited to below 2°C.
• Resilient reefs identified in bleaching refugia with diverse thermal phenotypes; no evidence of 'gene swamping' hindering adaptation.

Conclusions:

• Management strategies can promote adaptation in thermal refugia and warm spots.
• Curbing global warming to below 2°C is essential for coral reef survival.
• Urgent global action to limit warming by 2050 is paramount for long-term coral persistence.