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."
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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Greening activity, however, is conspicuously absent in the great Amazon Basin, home to the world's largest rainforest. Much of the basin shows either no greening or a loss of greening. This is little surprise: Between 2000 and 2005 Brazil alone lost an area of forest larger than the nation of Greece.
Forests and vegetation play a huge role in Earth's natural carbon cycle, because they suck large quantities of carbon dioxide out of the air. Specifically, Earth's plants and trees absorb about 25 percent of the planet's human-created carbon emissions.
Planting and expanding forests are considered to be one strategy of a much larger solution to rein in the planet's carbon concentrations, which have catapulted in last 100 years: Carbon dioxide concentrations are now the highest they've been on Earth in some 15 million years.
China's intensive greening efforts, however, have been vastly overshadowed by civilization's still-rising carbon emissions - which at the current pace likely won't even peak for another decade. And China is largely to blame. The booming industrial giant's carbon-spewing coal factories are far outpacing its expansive solar farms and greening efforts. It's the biggest emitter of greenhouse gases on Earth.
So while India and China look greener on the map, they're loading the atmosphere with historically unprecedented levels of potent greenhouse gases.