Why observing trees near volcanoes is a great early warning image

Scientists have discovered that trees near volcanoes often change color when the volcano becomes more active. Recently, a team of researchers from NASA and the Smithsonian Institution (USA) collaborated to conduct a study to monitor these changes from space.

 

The results showed that before the volcano erupted, magma rose from the ground, releasing gases such as carbon dioxide (CO₂) and sulfur dioxide (SO₂). The plants absorbed the CO₂, causing their leaves to become greener and thicker. Scientists used satellite imagery from NASA's Landsat 8 and data from the Airborne Validation Unified Experiment: Land to Ocean (AVUELO) aircraft to detect this phenomenon.

' This all-natural early warning system for volcanic eruptions is highly reliable, ' said Florian Schwandner, chief of Earth Sciences at NASA's Ames Research Center. ' The goal here is to improve observations and provide earlier warnings. '

 

Volcanic eruptions are dangerous and unpredictable. About 10% of the world's population lives in areas that could be affected. People near volcanoes face risks such as flying rocks, ash clouds, and toxic gases. Even people far away can experience mudflows or tsunamis from eruptions. Because eruptions cannot be prevented, early warning is crucial.

Monitoring volcanic activity from space isn't easy. Scientists can detect SO₂ because it's easier to measure, but CO₂ from volcanoes – the earliest sign of rising magma – is harder to measure. ' A volcano emitting a small amount of CO₂ that signals an eruption won't show up well on satellite images, ' explains Robert Bogue, a volcanologist at McGill University.

Traditionally, researchers have had to travel to volcanoes to measure CO₂ directly. But with more than 1,300 potentially active volcanoes around the world – many of them in remote, isolated areas – monitoring the response of plants has become a simpler, yet still accurate, solution.

Nicole Guinn, a volcanologist at the University of Houston, used satellite imagery from Landsat 8, NASA's Terra satellite, and ESA's Sentinel-2 to study vegetation near Sicily's Mount Etna. Her research found a clear link between leaf color and CO₂ from the volcano.

To confirm the accuracy of the satellite imagery, climate scientist Josh Fisher led another field study in March 2025. His team measured CO₂ and collected leaf samples near the Rincón de la Vieja volcano in Costa Rica. ' This study is an interdisciplinary combination of ecology and volcanology, ' Fisher said.

Of course, using trees as indicators of volcanic eruptions has its limitations. Some volcanic areas do not have many trees around them, and environmental factors such as weather or plant diseases can affect tree growth. But past success shows the potential of this approach.