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IANS
Using 29 years of data from satellite imageries, NASA scientists have found extensive greening in the Arctic region, thanks to rising temperatures.
The northern reaches of North America are getting greener, said the 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, the researchers said.
With 87,000 images taken from Landsat satellites, the researchers found that western Alaska, Quebec and other regions became greener between 1984 and 2012.
Landsat is a joint NASA/US Geological Survey programme that provides the longest continuous space-based record of the Earth's land vegetation in existence.
"It shows the climate impact on vegetation in the high latitudes," said one of the researchers Jeffrey Masek from NASA's Goddard Space Flight Centre in Greenbelt, Maryland.
Temperatures are warming fast in the Arctic which has led to longer seasons for plants to grow in and changes to the soils.
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 findings were reported in the journal Remote Sensing of Environment.
Landsat, like other satellite missions, can use the amount of visible and near-infrared light reflected by the green, leafy vegetation of grasses, shrubs and trees to characterise the vegetation.
Then, with computer programmes that track each individual pixel of data over time, researchers can see if an area is greening -- if more vegetation is growing, or if individual plants are getting larger and leafier.
If, however, the vegetation becomes sparser, the scientists would classify that area as browning.
