The Azores, a crucial biodiversity hotspot in the North Atlantic, faces an urgent and accelerating threat. Our new research reveals the dramatic, group-specific impacts of climate change on the fragile coastal marine ecosystems of the archipelago.

The missing piece in the azorean climate picture

While previous studies have examined the effects of rising temperatures and changing conditions on Azorean terrestrial life and offshore marine zones, a comprehensive assessment for the coastal marine ecosystems — the economic and ecological lifeblood of the local communities — had been missing. Understanding these specific coastal dynamics is essential for climate adaptation.

Our multi-model approach

We built a vast ensemble of Species Distribution Models (SDMs) for 277 key coastal species, including marine mammals, fish, turtles, seabirds, kelp, and corals. We projected their distributions under both a low (SSP1-1.9) and a high (SSP5-8.5) carbon emissions scenario through 2100. This allowed us to map future changes in species richness and community composition, known as beta diversity.

Tackling big data for small islands

The sheer scale of this project—fitting up to 50 models for each of the nearly 280 species using 10 different machine learning algorithms—required intensive computational resources. We tackled this technological challenge by leveraging a high-performance computing cluster using a parallelised workflow. Crucially, to ensure the accuracy and robustness of our projections, we modeled species across their full range in the entire North Atlantic to accurately capture their complete climate tolerance curves.

Main finding: a new map of vulnerability

Our models project a significant decrease in suitable climate across the archipelago. Under the worst-case scenario (SSP5-8.5), up to 25% of the modelled coastal area could lose its suitable climate by the end of the century. The impacts are highly variable across taxonomic groups:

• Marine mammals and seabirds face the most substantial loss, leading to a projected major loss of species, particularly near the southern islands of Santa Maria, São Miguel, Pico, and Faial.
• Coastal fish are less threatened by overall range loss but will undergo significant reshuffling (species replacement), particularly in pelagic fish communities, which has major implications for local fisheries.
• Climate refugia—areas projected to sustain species presence over the entire period—are primarily concentrated in the northernmost coastal zones of the archipelago.

Conservation and management for a changing ocean

These findings provide vital, regional insight that will inform local climate change adaptation efforts and directly support the goals of the UN 2030 Agenda. Our results offer critical guidance for conservation and management:

• Protect Refugia: Conservation efforts must focus on prioritising the northern coastal refugia, creating safe migration pathways for larger, vulnerable species like whales.
• Adapt Fisheries: Integrating our turnover forecasts into fishery management is essential to anticipate and respond to food web changes driven by the reshuffling of fish communities.
• Curb Local Stressors: For the southern islands where species redistribution is expected to be most significant, policymakers must urgently focus on curbing existing pressures like over-exploitation and habitat degradation to enhance ecosystem resilience against the combined threat of climate change.