Boreal forests shifted north and expanded over four decades

The boreal forest, the world’s largest terrestrial biome, is warming faster than any other forest type. Feng et al., 2026 analyzed the biome from 1985 to 2020 using the longest, highest-resolution satellite record of calibrated tree cover and confirmed a northward shift in forest cover over the past four decades.

Landsat imagery was central to the work. The team applied machine learning to process 224,026 scenes from Landsats 4, 5, 7, and 8 to produce annual, 30-meter maps of tree cover across the entire boreal biome. They downscaled and extended calibrated MODIS Vegetation Continuous Fields data to 30-meter resolution, creating a 36-year time series (1984–2020) that provided unprecedented spatial detail for tracking change.

The analysis found that boreal forests both expanded and moved poleward: total area grew by 0.844 million km² (a 12% increase) and mean latitude shifted northward by 0.29°, with gains concentrated between 64° and 68° north.