Volcanos have been notoriously hard to predict when they may explode, and that leaves people in danger. But scientists may have a new ally in their early warning system - trees!

Or more specifically, tree leaves. Scientists already knew that tree leaves change color when a nearby volcano becomes more active, but they now hope to observe the mechanism using satellite imagery.

“Volcanoes emit a lot of carbon dioxide,” said Robert Bogue, a volcanologist from McGill University. However, “a volcano emitting the modest amounts of carbon dioxide that might presage an eruption isn’t going to show up in satellite imagery,” he explained. Carbon dioxide does show up, however, in trees’ foliage, making it greener and more lush. As such, the NASA and Smithsonian collaboration is bringing together volcanologists, botanists, and climate scientists to investigate how researchers can use trees to monitor volcanic activity.

The approach has constraints, however. For example, some volcanoes aren’t close enough to trees for satellite images to be useful, and different trees can experience different responses to carbon dioxide. Furthermore, fires, weather events, and plant diseases can make satellite data difficult to interpret. But the truth is that no single feature can perfectly predict volcanic activity.

Still, any type of early warning of a potential eruption can be helpful and would give nearby residents time to evacuate and help save lives.