Science
Earth is greener than it was 20 years ago, but not why you think
IMAGE: NASA
Two NASA satellites have watched Earth grow greener over the last 20 years — in large part because China is hellbent on planting millions of trees.
Earth's greening — meaning the increase in areas covered by green leaves — has made the greatest gains in China and India since the mid-1990s. "The effect comes mostly from ambitious tree-planting programs in China and intensive agriculture in both countries," NASA wrote on Tuesday as it released maps of the planet-wide changes.
China kickstarted its tree-planting mobilizations in the 1990s to combat erosion, climate change, and air pollution. This dedicated planting — sometimes done by soldiers — equated to over 40 percent of China's greening, so far.
“Once people realize there is a problem, they tend to fix it,” Rama Nemani, a scientist at NASA’s Ames Research Center and a coauthor of the research, said in a statement. “In the 1970s and '80s in India and China, the situation around vegetation loss was not good. In the 1990s, people realized it, and today things have improved. Humans are incredibly resilient. That’s what we see in the satellite data.”
IMAGE: NASA
Previous NASA research found that Earth's increased greenery is largely due to skyrocketing levels of carbon-dioxide saturating the air — which plants use to grow. But this new research argues that tree and crop planting plays a bigger, outsized role.
Overall, much of the greening in China and India comes from the "intensive" cultivation of crops, NASA found. This accounts for 32 percent of the greening in China and 82 percent in India.
"Production of grains, vegetables, fruits and more have increased by 35 to 40 percent since 2000," NASA said.
Zooming out, about one-third Earth's vegetated lands experienced greening, including a conspicuous portion of North America stretching from southern Mexico to high into the boreal forests of Canada.
Vast swaths of the Arctic tundra are greening too as the Arctic continues its historically unprecedented warming trend — which is also thawing the carbon-saturated ground (permafrost) and melting massive ice sheets.
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