Connecting optical remote sensing of plant photosynthesis with biogenic volatile organic compound emissions.

Plant biogenic volatile organic compounds (BVOCs) play a critical role in atmospheric chemistry by forming ozone and secondary organic aerosols, making them key agents in regulating air quality and influencing climate. However, current models usually rely on limited site-specific data and indirect inputs, introducing significant uncertainties in BVOC predictions. We propose remote sensing of photosynthetic optical signals, such as the carotenoid-sensitive photochemical reflectance index (PRI) and Chl/carotenoid index (CCI) and sun-induced fluorescence (SIF), to help reduce these uncertainties. These indices are functionally linked, albeit indirectly for SIF, to isoprenoid BVOC emissions via carotenoid biosynthesis. In this Viewpoint, we explore the potential of this connection to estimate and constrain BVOC emissions at multiple scales. We synthesize key aspects, recent advances, and research uncertainties, and propose empirical and scaling roadmaps for integrating optical signals with BVOCs, highlighting their connectivity under abiotic stress (e.g. drought, heat) and across seasonal dynamics. This integration represents a critical step toward reducing model uncertainties, improving large-scale BVOC monitoring, and enhancing our understanding of their role in atmospheric chemistry and climate. By providing a more comprehensive framework for linking plant physiological processes to atmospheric chemistry, this approach strengthens our ability to predict ecosystem responses to climate change.