The northern reaches of North America are getting greener, according to a NASA study that provides the most detailed look yet at plant life across Alaska and Canada. In a changing climate, almost a third of the land cover - much of it Arctic tundra - is looking more like landscapes found in warmer ecosystems.
With 87,000 images taken from Landsat satellites, converted into data that reflects the amount of healthy vegetation on the ground, the researchers found that western Alaska, Quebec and other regions became greener between 1984 and 2012. The new Landsat study further supports previous work that has shown changing vegetation in Arctic and boreal North America.
The northern reaches of North America are getting greener, according to a NASA study that provides the most detailed look yet at plant life across Alaska and Canada. In a changing climate, almost a third of the land cover - much of it Arctic tundra - is looking more like landscapes found in warmer ecosystems.
With 87,000 images taken from Landsat satellites, converted into data that reflects the amount of healthy vegetation on the ground, the researchers found that western Alaska, Quebec and other regions became greener between 1984 and 2012. The new Landsat study further supports previous work that has shown changing vegetation in Arctic and boreal North America.
Landsat is a joint NASA/U.S. Geological Survey program that provides the longest continuous space-based record of Earth's land vegetation in existence.
"It shows the climate impact on vegetation in the high latitudes," said Jeffrey Masek, a researcher who worked on the study and the Landsat 9 project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Temperatures are warming faster in the Arctic than elsewhere, which has led to longer seasons for plants to grow in and changes to the soils. Scientists have observed grassy tundras changing to shrublands, and shrubs growing bigger and denser - changes that could have impacts on regional water, energy and carbon cycles.
With Landsat 5 and Landsat 7 data, Masek and his colleague Junchang Ju, a remote sensing scientist at Goddard, found that there was extensive greening in the tundra of western Alaska, the northern coast of Canada, and the tundra of Quebec and Labrador. While northern forests greened in Canada, they tended to decline in Alaska. Overall, the scientists found that 29.4 percent of the region greened up, especially in shrublands and sparsely vegetated areas, while 2.9 percent showed vegetation decline.
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Image credit: Western Alaska
