Marine cloud brightening (MCB) could be implemented as a regional strategy to reduce heat and light stress on coral reefs during marine heatwaves. Modelling suggest that the potential exists to reduce light and thermal stress that cause coral bleaching on the Great Barrier Reef. Despite three decades of theoretical research on MCB as a solar radiation management technology there has been no outdoor field experimentation directly evaluating the concept. We have now progressed development of seawater atomisation technology to a scale which allows us to empirically test foundational assumptions. These include the ability to generate sufficient sea salt aerosols within a suitable size range and reliance on natural mixing processes to transport them into cloud. Through an aircraft based experimental campaign we examine the cloud microphysical response to the additional sea spray cloud condensation nuclei. This talk will provide an overview of the results of the Australian Marine Cloud Brightening program focusing on the results of the most recent field campaigns in 2023 and 2024. From its inception our research program has involved consultation and participation of indigenous traditional custodians of the reef and has proceeded within the regulatory oversight of one of the world’s most actively managed marine estates.