Artificial light at night is causing ecosystems to release more carbon into the atmosphere, according to new research that matched satellite observations with decades of carbon data from the two most light-polluted continents on Earth.
The study, published Wednesday in the journal Nature, is the first to show how light pollution affects the carbon cycle of ecosystems across North America and Europe. Researchers focused on 86 monitoring sites, using the data to measure how much carbon moves between the land and atmosphere every half hour.
They found that ecosystems exposed to brighter nights released more carbon into the atmosphere through respiration — where plants, animals and microbes release carbon dioxide — without an increase in photosynthesis to remove carbon dioxide from the air. That imbalance means illuminated landscapes release more carbon at night than darker areas. Light pollution, despite being visible from space, remains largely absent from climate models.
“Light pollution is one of humanity’s most visible environmental changes, but its impacts are often hidden,” said Alice Johnston, senior lecturer in environmental data science at Cranfield University and the study’s lead author. “This is a widespread issue that’s changing how ecosystems function, disrupting energy flows, animal behaviour, habitats and natural patterns. Put simply, brighter nights lead to greater carbon release, which is bad news for our planet.”
