Boreal Forests Are Shifting North
The boreal forest, the world’s largest terrestrial biome, is warming faster than any other forest type. To understand the changing dynamics of boreal forests, Feng et al., 2026 analyzed the biome from 1985 to 2020, taking advantage of the longest and highest resolution satellite record of tree cover calibrated to date. The study, published in February in Biogeosciences with four co-authors from NASA’s Goddard Space Flight Center, confirms a northward shift in boreal forest cover over the past four decades. Landsat imagery played a central role in this study: researchers applied machine learning to process 224,026 scenes collected by Landsats 4, 5, 7, and 8 to create 30-meter resolution annual maps of tree cover across the entire boreal biome. They reduced and expanded calibrated data from continuous MODIS vegetation fields to 30 meter resolution, creating a 36-year time series (1984-2020) that provided unprecedented spatial detail for tracking forest changes.
The analysis revealed that boreal forests grew in size and moved north. Forests expanded by 0.844 million km² (a 12% increase) and moved northward by 0.29° midlatitude, with gains concentrated between 64 and 68°N. Their work also highlighted the ability of new growth to act as a carbon sink. Young boreal forests (up to 36 years old) contain approximately 1.1 to 5.9 petagrams of carbon (Pg C) with the potential to sequester an additional 2.3 to 3.8 Pg C if allowed to mature. Landsat’s long time series of highly calibrated data allows researchers to study how ecosystems have changed over decades, a crucial insight into our changing world.
