Digital fabrication of Hybrid Nature-based Solutions as new opportunity for coastal climate change adaptation.

Coastal areas face unprecedented challenges from accelerating sea-level rise, increasing urbanisation and biodiversity loss, necessitating sustainable coastal protection strategies that go beyond traditional engineering approaches: While Nature-based Solutions (NbS) offer ecological benefits, their implementation faces constraints in space, timely readiness and standardisation. Hybrid Nature-based Solutions (HNbS) have emerged as promising alternatives, yet current taxonomic classifications remain ambiguous and insufficient to accommodate emerging technologies. This synthetic review analyses the evolution and current role of NbS in coastal climate change adaptation through a comprehensive juxtaposition of design principles and functional mechanisms of engineered and nature-based coastal defences. The review synthesises knowledge from sustainable climate adaptation and digital fabrication literature to establish precise taxonomic classifications for solutions that integrate engineered and nature-based approaches, namely HNbS. The analysis reveals gaps in the existing HNbS taxonomy, particularly regarding structures enabled by digital fabrication technologies. The three identified, distinct categories of HNbS are: (1) Hybrid Nature-based Strategies, combining engineered and natural elements at planning scales; (2) Hybrid Nature-based Modules, integrating both components within individual structures; and (3) Confluent Hybrid Nature-based Solutions, representing an emerging category where engineering and natural systems converge at material or microorganism scales, offering distinctly engineered infrastructures with natural characteristics. While contemporary hybrid approaches are being implemented, Confluent Hybrid Nature-based Solutions under research, may face a critical timing mismatch due to a gap between lengthy innovation timelines and urgent adaptation needs. Dynamic Adaptive Policy Pathways provide a framework for strategically accommodating these emerging innovations, enabling early-stage solutions and performance demonstration under real-world conditions. The new taxonomic framework outlined in this study prevents imprecise terminology and provides a foundation for robust, low-regret coastal adaptation strategies addressing contemporary and future coastal pressures like climate change impacts and biodiversity conservation requirements.