"Between 2000 and 2020, 42% of tree lines around the world crept upward, largely because of climate change. But 25% moved downhill, seemingly because of factors such as land use changes and wildfires."
"As the climate warms, tree lines are generally understood to move up, because regions that were previously too cold for trees to survive now have higher, more tree friendly temperatures. ...
But new research, published in the International Journal of Applied Earth Observation and Geoinformation, paints a more complicated picture: Between 2000 and 2020, 42% of tree lines shifted up, true. But 25% of them actually moved downhill.
Sabine Rumpf, an ecologist at the University of Basel in Switzerland, said many studies of tree line shifts tend to be concentrated in limited geographic areas. A preponderance are based primarily on data from North America, Europe, and the Himalayas, where researchers are more likely to have funding to head to the field to take measurements themselves.
“But that also means that a large proportion of the surface of our planet is so understudied,” Rumpf said. “And [to remedy] that, remote sensing data [are] really amazing because you can get a truly global picture, even though there’s nobody, or too few people, observing things in the field.”"
