A framework and findings from a large 3-year research program designed to inform climate actions for seagrasses is presented. The impetus for this program was the need to consider cumulative impacts and mitigation strategies for port developments. The focus was Posidonia sinuosa (Vulnerable IUCN Redlist) along the temperate coastline of WA, a heatwave hotspot where both historic loss and recent climate impacts have occurred. Four interconnected research nodes: historical ecology, thermal ecophysiology, genomics and experimental ecology were implemented to assess the feasibility of climate actions (e.g. assisted migration). Historical analysis indicated long-term decline in seagrass condition across 3o latitude associated with increased temperature, supporting the need for climate actions. Genomic analysis detected a highly connected meta-population although thermal optima varied among regions presenting opportunities for climate interventions. Genome by environment analyses identified 4.7% of genes putatively adapted, associated with temperature, and aligned with variations in thermal optima. Finally experimental mesocosm studies with plants from different regions showed greater tolerance to heatwaves when thermal optima was higher, highlighting the potential for assisted migration actions. This program has delivered a step-change in knowledge for temperate seagrasses and we are well placed to navigate regulations and implement these climate actions.