NASA study displays Arctic greening


Click to enlargeNASA/Cindy Starr

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…

“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…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 the higher resolution Landsat data, the researchers also found a lot of differences within areas – one pixel would be brown, and its neighbors green, noted Ju. “It’s very localized,” he said. “The vegetation is responding to the microclimates. That’s the benefit of using Landsat data, is that we can reveal this spatial variation over very short distances.”

With the large map complete, researchers will focus on these short distances – looking at the smaller scale to see what might control the greening patterns, whether it’s local topography, nearby water sources, or particular types of habitat. They also plan to investigate forested areas, particularly in the greening Quebec.

❝ “One of the big questions is, ‘Will forest biomes migrate with warming climate?’ There hasn’t been much evidence of it to date,” Masek said. “But we can zoom in and see if it’s changing.”

At this point you really can’t predict gains or losses. The dramatic changes only point out how quickly climate change is affecting some regions unchanged for tens of thousands of years.

RTFA for technical details how NASA scientists did the observational work.

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