Planning sustainable lighting for biodiversity and society

Urban planners continuously face the challenge of reducing artificial lighting to protect biodiversity while ensuring urban residents comfort and safety at night. Striking this balance is crucial for supporting urban residents broadly, yet it remains insufficiently explored in current research. In this paper, we integrate remote sensing and ecological modelling to assess species’ requirements around light pollution reduction with socio-economic modelling to evaluate human residents’ acceptance of various street-lighting adjustments, aiming to identify the optimal lighting compromises for Montpellier, France, a mid-sized European city. We show that, depending on the spatial context, both trade-offs and synergies can emerge when implementing light pollution mitigation measures. By integrating results into an RShiny application  https://sustainlight.sk8.inrae.fr/, we enabled urban planners to prioritize actions for each streetlight. Our findings underscore the importance of tailoring lighting policies to the specific environmental and social context rather than adopting a universal 'one-size-fits-all' approach. We thus call for the adoption of a socio-ecological perspective when it comes to sustainable lighting policies.