With 87,000 images from Landsat satellites, converted into data reflecting the amount of healthy vegetation on the ground, researchers found that western Alaska, Quebec and other regions in Canada became greener between 1984 and 2012.
The Landsat study covered wide-scale changes in the over 10.6 million sq-km landscape and was published in Remote Sensing of Environment in April 2016. Jeffrey Masek, a researcher with NASA’s Goddard Space Flight Center and a co-author of the study, said the study gives us a “glimpse of how a warming climate is starting to alter global vegetation patterns.”
This new Landsat study also supports previous studies that have shown the changing vegetation in Arctic and boreal North America, according to Space Daily. Landsat is a joint NASA/U.S. Geological Survey program providing the longest, continuous space-based record of the Earth’s land vegetation in existence.
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, said, “It shows the climate impact on vegetation in the high latitudes.” He says that temperatures are warming faster in the Arctic region than elsewhere, and this has led to longer growing seasons and changes in the soil.
The scientists have observed what was once grassy tundra changing to scrub-lands, with shrubs growing bigger and denser as time goes on. Over time, this could have an impact on water, energy and the carbon cycle in these areas.
Scott Goetz, the deputy director and senior scientist at the Woods Hole Research Center in Massachusetts, says the study shows “a clear distinction between what’s happening in the tundra and Boreal regions of Canada and Alaska,” reports IFPress.com.
Overall, the study found that 29.4 percent of the Arctic region has become greener, especially in the scrub-lands and sparsely vegetated areas. Only 2.9 percent of these areas showed a decline, especially in the boreal forest regions, which have been defined as browning.
The Landsat Program
You have heard the word, Landsat, and probably have some inkling of what it is. Landsat is an Earth-orbiting satellite program that has produced continuous, calibrated observations of the Earth since the early 1970s with the very first Landsat satellite, launched on July 23, 1972. In 1975, NASA Administrator Dr. James Fletcher predicted that if one space-age development would save the world, it would be Landsat and its successor satellites.
Landsat uses the amount of visible and near-infrared light reflected by the green given off by vegetation. With a computer program, it then tracks each individual pixel of data over time. This way, scientists can actually see the greening of vegetation over time, or if the reverse is happening, the browning of vegetation.
Landsat satellites can actually see some of the smallest differences across a landscape, whereas other satellite instruments, such as the Advanced Very High-Resolution Radiometer (AVHRR), used on polar-orbiting satellites, use a broader bandwidth because they are primarily used for atmosphere and ocean studies, even though they also send back land studies.
With the finer resolution given by Landsat imagery, the scientists were able to mask out areas that burned, or are covered in water, focusing on vegetation. With this more detailed look, scientists will be able to see the correlation between habitat characteristics and greening or browning.
“The resolution with Landsat is drastically improved, it lets you look at the local effects of things like topography, such as in areas where you might have small woodlands or open areas,” Masek said. “You can do detailed studies of how climate impacts vary with geography.”
As was expected, researchers found some significant differences within some areas, where one pixel might be brown and its surrounding neighbors would be green. This was interesting, showing the vegetation is responding to micro-climate conditions. With the larger map having been generated, scientists can now focus on these small areas, seeing if the response is because of water resources or something else.
Scientists are also very interested in the greening of Quebec and plan on investigation the forested regions to better understand its local conditions more. “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.”
The accompanying video can also be seen on YouTube. It is interesting that of the over 31,000 viewers that watched the presentation, most of the comments were focused on, “What does this mean for global warming?” One person asked, “Can someone tell me if this is good or bad or both – and why?”
Most comments showed that people are beginning to realize that global warming is real, and we now have evidence to back that assertion up. That is why it is important to look at the bigger picture when watching the video. While it focuses on the Arctic region of North America, changes in climate in other parts of the world are beginning to change dramatically, too.
