Ocean Glow · Ocean Glow: Controls on ocean productivity using ocean fluorescence detected from space

Primary production in the ocean is critically important for human wellbeing - it regulates atmospheric carbon dioxide as well as sustaining almost all ocean life. But models predicting the impacts of climate change do not agree on the sign of ocean primary production in the coming century. Currently, satellite observations tell us how ocean primary productivity is changing, but not the underlying controls. Fieldwork and modelling show nutrient limitation is key, but there is currently no way to observe nutrient limitation at the scales needed to monitor climate change impacts or benchmark the accuracy of models. This project aims to overcome the scaling problem using direct, nutrient-regulated fluorescence signals passively emitted from phytoplankton and detected by satellite sensors in space. Although recorded for almost two decades, these signals have been confounded by uncertainty. In Ocean Glow I will take a two-pronged approach to break through the current blockage. In the first prong, a novel laboratory mesocosm facility will be constructed and used to quantify the key factors regulating phytoplankton fluorescence emission, in the same way that it is stimulated and detected by satellites. In the second prong I will connect these experimental results with the real world by undertaking field observations on research cruises through the global ocean, using approaches that I have pioneered in my previous research. Finally, I will use this ground-based assessment to perform data-informed deconvolution of the satellite fluorescence signal to observe nutrient limitation at a global, time-resolved scale using the existing, two-decade satellite record. In making a step change in the utility of satellite-detected fluorescence, Ocean Glow will deliver the tool needed to make mechanistic assessments of how climate change is impacting ocean productivity.