In a study led by Feng and colleagues and published in Biogeosciences in February 2026, researchers examined how boreal forests have changed by leveraging the longest and highest resolution satellite record of calibrated tree cover to date. The team included four co-authors from NASA's Goddard Space Flight Center, underscoring the central role of NASA Earth observation data in tracking long term ecosystem change.
The researchers used imagery from Landsat 4, 5, 7, and 8, applying machine learning techniques to process 224,026 individual scenes that span the boreal biome. From these data, they produced annual tree cover maps at 30 meter resolution across the entire boreal forest, creating a consistent record detailed enough to follow changes in forest cover and structure across decades and continents.
To build this record, the team downscaled and extended calibrated MODIS Vegetation Continuous Fields data to match the 30 meter Landsat resolution. This approach yielded a 36 year time series from 1984 to 2020, providing unprecedented spatial detail for monitoring how boreal forests expand, contract, or shift in response to climate and other drivers. The high resolution time series allowed the scientists to trace subtle but cumulative changes that would be difficult to detect with coarser datasets.
The analysis showed that boreal forests both increased in total area and shifted northward. Over the study period, the forests expanded by about 0.844 million square kilometers, corresponding to a 12 percent increase in forested area within the biome. The mean latitude of boreal forest cover moved north by roughly 0.29 degrees, with the greatest gains concentrated between 64 and 68 degrees north, indicating that new growth is taking hold in areas that were previously more sparsely forested.
Beyond mapping where forests are moving, the researchers also evaluated the carbon implications of these changes. Young boreal forests up to 36 years old were estimated to store between 1.1 and 5.9 petagrams of carbon. If these young stands are allowed to mature, they could sequester an additional 2.3 to 3.8 petagrams of carbon, highlighting their potential role as a carbon sink even as the biome responds to a warming climate.
Landsat's long, highly calibrated data record is crucial for this type of analysis because it provides consistent measurements across multiple satellite missions and decades. By combining machine learning with this multi mission archive, scientists can track how ecosystems such as the boreal forest respond over time to rising temperatures, shifting precipitation patterns, and other global changes. The new boreal forest maps demonstrate how a sustained Earth observation program can reveal slow moving but consequential transformations in one of the planet's most extensive and climate sensitive biomes.
A short video abstract produced for this work, "Boreal Shift," presents key findings from the study and visualizes the observed northward movement of the forests. The video explains how the Landsat record and advanced analysis methods make it possible to confirm that boreal forests are on the move and to quantify both their expansion and their changing role in the global carbon cycle.
Watch the video here
Related Links
NASA Landsat Science
Forestry News - Global and Local News, Science and Application
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