Forest space age: Satellites can track canopies and carbon storage

Forests are one of Earth’s greatest natural defenses against climate change. They absorb carbon dioxide, regulate rainfall, and shelter a huge portion of the planet’s biodiversity.

Yet for all their importance, large parts of the world’s forests remain poorly understood and hard to monitor – even with the help of space technology – and they remain vulnerable to both natural and human-driven change.

Until recently, forest monitoring relied heavily on ground teams manually measuring trees, mapping biodiversity, and estimating carbon stored in different ecosystems. These efforts, though essential, are slow, labor-intensive, and often constrained by difficult terrain or limited funding.

Now, a breakthrough is underway. The tools of modern space science are being directed toward Earth’s forests like never before. This marks the beginning of what scientists call the “forest space age” – a bold, global effort to transform our understanding of forests from above.

Tracking forest carbon from space

On April 29, the European Space Agency (ESA) will launch the Biomass mission. It will carry the first P-band radar into space, capable of seeing through dense forest canopies. This satellite is expected to revolutionize how we estimate forest structure and carbon storage.

P-band radar technology stands out because it can detect elements of forests that other sensors miss. It reaches past the leafy treetops and captures detailed information about trunks, stems, and branches — the key areas where trees hold carbon.

Biomass won’t be alone for long. Soon, the US–India NISAR mission will join it. This satellite carries an L-band synthetic aperture radar that complements Biomass’s P-band data.

Together, these missions will offer a multi-layered picture of forests. Add to that NASA’s GEDI lidar aboard the International Space Station, the Copernicus Sentinel-1’s C-band radar, and more missions in the pipeline, and the result is a powerful suite of tools monitoring forests from orbit.

Monitoring forests with satellites

Never before have so many instruments been trained on Earth’s forests at once. These satellites are not just capturing snapshots. They provide consistent, global-scale monitoring over time, allowing scientists to detect patterns and trends in forest health, loss, and growth.

ESA’s Climate Change Initiative’s Biomass Project is already using this wealth of data to analyze long-term forest changes.

By integrating historical and current satellite data, the project delivers a clear view of how biomass has changed year after year. This time-series approach reveals shifts in forest dynamics and provides essential input for climate models.

When satellite data is used together with global climate projections, it enables better predictions of how forests will react to temperature shifts, droughts, or human pressures. The scale and depth of data now available were once unthinkable. Yet space technology alone cannot give us the full picture.

Why groundwork still matters

Despite their reach and resolution, satellites can’t do everything. They can’t directly measure biomass or recognize plant species from above. Tropical forests, for instance, are home to staggering biodiversity. This complexity makes it hard for remote sensors to categorize forest types or species without help.

“Even the most advanced satellite can’t tell a mahogany from a Brazil nut tree without help from the ground, and there are more than ten thousand tree species in the Amazon alone,” said Professor Oliver Phillips from the University of Leeds.

Ground-based science is still vital. Forest ecologists and botanists work in jungles, swamps, and mountain forests to collect the details satellites miss. They measure tree height, diameter, species type, and carbon density, all while navigating unpredictable and sometimes dangerous conditions.

Forests rely on space technology

To make sure that space-based data reflects reality, scientists compare it with direct measurements from the ground. This process, called ground validation, is particularly important in tropical forests where tree diversity is high and canopy structure varies widely.

For this reason, long-term on-the-ground studies continue to play a critical role. They ensure accuracy, identify regional patterns, and help calibrate satellite instruments. Forests change slowly and subtly over time.

Only with repeat measurements at tree level can we detect those shifts and check if the satellite data aligns with what is actually happening on the ground.

Ground validation is not just a technical necessity. It is also a scientific collaboration that stretches across borders and disciplines, bringing together ecologists, geographers, botanists, and remote sensing experts.

Introducing GEO-TREES

To improve this collaboration and support local expertise, scientists launched a global project called GEO-TREES. It is an initiative designed to connect remote sensing specialists with field researchers and promote balanced partnerships around the world.

“The aim of GEO-TREES is to establish a sustainable funding mechanism to support ecologists and experts working in the forest to take the tree-by-tree measurements that are needed to validate satellite data products,“ noted ESA’s Biomass Mission manager, Klaus Scipal.

“GEO-TREES will implement rigorous ground-validation protocols and push for major investments in the people behind the data – particularly in the Global South, where much of the world’s biodiversity resides.”

Through GEO-TREES, there is now an effort to formalize funding pathways for fieldwork. This helps ensure that forest scientists on the front lines have the resources, training, and recognition they need to carry out accurate and consistent data collection.

Space missions and ground observations

Measuring trees, hiking through flooded forests, climbing into canopies – this is not easy work. Yet without these efforts, satellite missions would lack reliable reference points. The success of Earth observation depends on the dedication of those who live and work close to the forests.

“Satellites, such as our Biomass, offer a wealth of information to understand our changing world, but we must not forget those working tirelessly on the ground taking in situ measurements, often in difficult conditions, who allow us to have confidence in the data returned from space,” said Scipal.

That trust between space-based observation and field data is what gives global forest monitoring its strength. Both are needed, and both are now being more closely linked than ever before.

A new phase of planetary care

“The dedicated teams working in the field to collect vital ground-truth data are important to the success of our missions,“ added ESA’s Director of Earth Observation Programmes, Simonetta Cheli.

“Their contributions help ensure that our Earth Explorer missions deliver outstanding science – science that lies at the core of our FutureEO programme.”

As Earth faces increasing environmental pressures, forests will continue to play a critical role in regulating our climate and sustaining life. By combining the power of satellite technology with the knowledge and hard work of people on the ground, we are entering a new phase of planetary care.

The “forest space age” is more than a technological achievement. It is a worldwide collaboration between the skies and the soil, with the goal of understanding and protecting the forests we all depend on.

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