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The world is getting greener. Satellite images collected over the past decade show that there is more green vegetation on our planet, especially in China and India. NPR's Dan Charles reports.
DAN CHARLES, BYLINE: Chi Chen is a Ph.D. student at Boston University. And he's been analyzing satellite images of Earth pixel by pixel.
CHI CHEN: So we have millions of pixels to cover the entire globe.
CHARLES: He can monitor the earth's surface week by week and see how much of it's covered with green leaves. This week in the journal Nature Sustainability, he reported that between 2000 and 2017, the land on our planet grew more heavily covered with green vegetation for longer periods.
CHEN: The Earth's surface is getting greener.
CHARLES: The data don't tell us exactly why, but there are some interesting clues. You can see which places are getting greener or browner. And you can investigate what's been happening there. For instance, there's one section of Brazil that's lost vegetation.
CHEN: I personally checked the data. This is because of drought.
CHARLES: Oh, it's because of drought.
CHARLES: On the other hand, take China and India. They've been getting a lot greener. And this is not because of weather or climate change. It's because of human decisions. Molly Brown, a geographer at the University of Maryland, has seen this greening up close.
MOLLY BROWN: These are really good examples of how policy can really make a difference.
CHARLES: The greening in India, she says, is because of a huge expansion of irrigated agriculture.
BROWN: Instead of having just crops when it's raining, they also have a whole, you know, six months of cropping and greenness when it's not raining.
CHARLES: This kind of green isn't really so great for the environment. It drains groundwater, gets wiped away at harvest. And the extra fertilizer farmers use releases greenhouse gases. In China, though, much of the new green is from a massive reforestation effort - the government's attempt to prevent dust storms.
BROWN: They are really doing a good job. They have very large and comprehensive tree planting, tree maintenance.
CHARLES: And those trees will stay there, she says, capturing dust and also carbon dioxide - the greenhouse gas - storing it in wood and roots and soil. Dan Charles, NPR News.
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