"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.
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.
“The greening trend was unmistakable,” the researchers wrote in an April 2016 paper in Remote Sensing of Environment."
"To assess the North American high-latitude vegetation response to the rising temperature, we derived NDVI trend for 91.2% of the non-water, non-snow land area of Canada and Alaska using the peak-summer Landsat surface reflectance data of 1984–2012. Our analysis indicated that 29.4% and 2.9% of the land area of Canada and Alaska showed statistically significant positive (greening) and negative (browning) trends respectively, at significance level p < 0.01, after burned forest areas were masked out. "