BY THE OPTIMIST DAILY EDITORIAL TEAM
The next time a volcano begins to stir, the first signs might come not from smoke or rumbling earth, but from the trees nearby. According to a new NASA-Smithsonian study, trees growing near volcanoes become visibly greener as underground magma releases carbon dioxide, offering a subtle but telling clue that satellites can now detect from space.
This emerging technique could give volcanologists an earlier window into potential eruptions, especially in remote or dangerous regions. As volcanologist Florian Schwandner of NASA’s Ames Research Center explained, “Volcano early warning systems exist. The aim here is to make them better and make them earlier.”
A greener signal from below
When magma begins to rise toward the surface, it releases gases such as carbon dioxide and sulfur dioxide. Sulfur dioxide is relatively easy to detect with satellite sensors, but carbon dioxide is harder to track due to its already high background levels in the atmosphere. Still, carbon dioxide often escapes earlier in the eruption process, and it turns out trees respond to it.
“Trees absorb carbon dioxide, and in response, their leaves can grow more vibrant and healthy-looking,” said climate scientist Joshua Fisher of Chapman University. That response creates a shift in leaf color and density that can be picked up by satellite instruments.
Satellites spot the difference
The NASA-Smithsonian team, in collaboration with researchers from McGill University and the University of Houston, used satellite imagery from Landsat 8, NASA’s Terra, and ESA’s Sentinel-2 to track vegetation changes near Mount Etna in Sicily. Volcanologist Nicole Guinn, who led the satellite analysis, said the study was the first to show a strong connection between greener tree leaves and carbon dioxide emissions from magma.
Detecting volcanic activity from above offers clear advantages. Of the roughly 1,350 active volcanoes on Earth, many are located in areas that are hard to access or dangerous to study on the ground. Satellites provide a much-needed view.
Measuring leaf color and gas levels on the ground
Still, satellite data needs confirmation. During a March 2025 NASA mission called the Airborne Validation Unified Experiment: Land to Ocean, scientists flew a spectrometer-equipped plane over Panama and Costa Rica to gather plant data, while field teams collected leaf samples near Costa Rica’s Rincon de la Vieja volcano.
Fisher, who directed the campaign, described the project as a “two-way interdisciplinary intersection between ecology and volcanology.” His team also measured carbon dioxide levels to understand how much of the gas trees are absorbing, offering insights not only into volcanoes but also into future climate scenarios.
Limitations and real-world results
While promising, tree-based monitoring has limits. Not all volcanoes are in forested areas, and external factors like fires, droughts, or disease can affect tree health and make satellite signals harder to interpret. Trees in different ecosystems may also respond differently to carbon dioxide exposure.
Yet in places where conditions align, the results can be life-saving. Schwandner recalled his work upgrading sensors at the Mayon volcano in the Philippines. In December 2017, the detection of elevated volcanic gases prompted evacuations before an eruption struck the following month. Thanks to early warnings, over 56,000 people were moved to safety with no casualties reported.
Scientists are clear that no single data point will predict an eruption. But monitoring how trees react to volcanic carbon dioxide could become a powerful addition to existing methods such as seismic monitoring and ground deformation.
“There’s not one signal from volcanoes that’s a silver bullet,” Schwandner said. “But it will be something that could change the game.”
