Urban lighting: balancing biodiversity and inhabitants
June 25 2025In collaboration with INRAE, the Muséum national d’Histoire naturelle, and La TeleScop, Chloé Beaudet, doctoral student at AgroParisTech, and Maia David, professor of environmental economics at AgroParisTech, participated in a groundbreaking study in the Montpellier Méditerranée metropolitan area. Their goal was to compare the needs of six groups of species sensitive to nighttime lighting with local inhabitants’ expectations for public lighting. The study resulted in the production of a map cross-referencing the needs of biodiversity and inhabitants. This map identifies different areas where actions on public lighting are mutually beneficial and those where compromises are necessary. The results were published in the journal Nature cities.
A sharp increase in light pollution
In recent years, light pollution has been increasing rapidly, driven by urbanization, the proliferation of light sources, and the widespread use of LEDs. While these technologies are more energy-efficient, they have also made it possible to increase lighting, sometimes to excessive levels. This artificial light disrupts the biological rhythms of many animal species, altering their nocturnal behavior, reproduction, and feeding habits. It also has proven effects on human health, particularly on sleep and the biological clock.
Mapping biodiversity needs in relation to inhabitants' expectations
During this study, scientists mapped light pollution using satellite images and cross-referenced this data with the ecological needs of six animal groups (birds, two groups of insects, two groups of bats, amphibians) and the responses of a survey of 1,148 inhabitants of the Montpellier metropolitan area. This city was chosen for its size, which corresponds to that of a medium-sized European city, and its proximity to the Cévennes National Park, which is home to nearly 2,400 animal species and more than 10,000 plant species. Light pollution in this area can be a problem, disrupting the day-night cycles, reproductive behavior, feeding habits, and orientation of nearby species. As a result, scientists have been able to create a strategic map identifying, street by street, areas where reducing lighting would benefit biodiversity without causing social rejection. It also allows for targeting sectors where compromises or technical adjustments are needed to reconcile the various issues.
An app to check out the results
To support public policy, researchers have developed SustainLight, an interactive web application in English. It allows elected officials, technicians, and citizens to explore the study’s results at the metropolitan level. Users can view priority areas, compare lighting scenarios, and identify the solutions that best balance biodiversity and quality of life. It is a practical tool for turning science into action.