Nature
PUBLISHED
The world’s largest terrestrial biome is changing fast, so much so that Earth’s appearance from space will be subtly shifting in color. Faced with warming temperatures, boreal forests are gradually creeping northward toward cooler regions in the planet’s highest latitudes.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.The boreal forest, also known as the taiga, is a biome defined by vast coniferous forests made up of evergreen trees, such as pines, spruces, and larches. Along with an abundance of flora, they’re home to all kinds of wonderful fauna, from brown bears and elk, to bison and beavers, as well as owls, eagles, and other rare birds.
The biome stretches in a broad band across the upper regions of North America and Eurasia, wrapping around the Northern Hemisphere like a green belt. This includes parts of Alaska, Canada, Iceland, Scandinavia, Russia, and some bits of Asia.
This location, however, means this ecosystem is especially vulnerable to climate change. It’s estimated that the boreal forest biome is warming four times faster than the global average, putting immense pressure on the rich wildlife that lives here.
In a new study, researchers from terraPulse and the NASA Goddard Spaceflight Center tracked changes in boreal forests using the longest and highest-resolution satellite record of tree cover assembled to date.
Covering the years 1985 to 2020, the data was crunched by machine learning algorithms to process 224,026 images collected by Landsat satellites 4, 5, 7, and 8. This produced incredibly detailed maps of tree cover across the entire boreal biome at a resolution of just 30 meters (98 feet).
It showed a startling rate of change. Over the course of the 35 years, the boreal forest biome has grown by 844,000 square kilometers (325,870 square miles), an increase of around 12 percent. All of this growth occurred in the north, meaning the green belt has shifted towards the North Pole by an average of 0.29° latitude.
This expansion may seem like an optimistic trend, but the reality is more complex. Although there was growth in the north, significant parts of the southern margins were lost.
It also suggests that a significant number of older trees have died off, offset by the new growth of young forests. Since small, juvenile trees are not as effective at “sucking up” carbon from the atmosphere, the paper notes the recent trend could have “direct implications for the region's role in the global carbon cycle.”
“These changes are not only spatially extensive but demographically consequential: they reflect a growing fraction of young forests with distinct structural and functional attributes that position them as dynamic agents of carbon sequestration. Understanding the contribution of these forests to current and future carbon stocks is essential for anticipating the net climate feedbacks emerging from boreal ecosystems,” the paper concludes.
The study is published in the journal Biogeosciences.
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