Yes, satellite data show that the planet has become greener this century, and China and India are a big reason why. A NASA-led study published in Nature Sustainability in February 2019 found that global green leaf area grew by about 5% between the early 2000s and 2017, an increase NASA compared to the area of all the Amazon rainforests. China and India together produced roughly one-third of that gain, although they hold only about 9% of the world's vegetated land.
The finding surprised many people, because both countries are better known for smog, rapid industrialisation and pressure on land. The explanation lies in deliberate land management: huge tree-planting programmes in China and more intensive farming in both countries. That also means "greener" is not the same as "healthier for nature", which is the part most headlines left out.
What the satellites measured
The research team, led by Chi Chen and Ranga Myneni of Boston University with NASA Ames scientist Rama Nemani, used data from the MODIS instruments on NASA's Terra and Aqua satellites. MODIS has photographed almost every point on Earth up to four times a day for about two decades, at a resolution of around 500 metres per pixel.
The key variable is leaf area: how much green leaf surface covers each patch of ground, and how that changes year on year. It is a measure of change, not of total greenness. That is why the Amazon or the forests of eastern North America do not stand out on the maps, even though they are already very green.
Globally, about a third of vegetated land showed greening between 2000 and 2017, while about 5% showed browning.
NASA's map of change in leaf area across Asia. Darker green marks places where leaf cover increased most; much of eastern China and the Indian subcontinent stands out.
China: forests planted on purpose
At least a quarter of the global gain was in China. According to the study, about 42% of China's contribution came from programmes to protect and expand forests, and another 32% from cropland.
Those programmes have a long history. After severe floods, dust storms and soil erosion in the late 20th century, Beijing launched large schemes such as the "Three-North Shelterbelt" in the north and the Grain for Green project, which paid farmers to convert steep or degraded fields back to trees and grass. Citizens have long been encouraged to take part in national tree-planting days. The aims were practical: hold soil in place, reduce flooding and slow desertification, with carbon storage as a welcome extra.
It was once known as the "sea of death", but after decades of greening, it's now famed for the "Kubuqi model" that tamed one of China's most formidable deserts. #desertification pic.twitter.com/07Orh6iZM0
— China Xinhua News (@XHNews) August 6, 2018
The Kubuqi Desert in Inner Mongolia, mentioned in this Xinhua post, is a showcase example. Restoration work there, led since 1988 by the Elion Resources Group with government backing, is reported to have brought vegetation back to about a third of the desert by 2017.
India: the greening came mostly from farms
India's story is different. About 82% of its greening came from cropland. The total area under crops changed little; instead, farmers harvested the same fields more than once a year, using fertiliser and irrigation to keep land green for more months. Food output of grains, vegetables and fruit in both countries rose by roughly 35–40% after 2000.
Tree planting also plays a role. In July 2017 the state of Madhya Pradesh reported planting about 66 million saplings in a single 12-hour campaign, part of a wave of large state drives. Such totals are self-reported, and how many saplings survive is much harder to know than how many go into the ground.
NASA's chart of change in leaf area, in percent per decade, by country or region. China (about 10%) and India (about 6.5%) far exceed the global average of 2.3%, ahead of the EU, Canada, Russia and the United States.
Why "greener" does not mean "solved"
It is tempting to read the maps as good news for the climate and for wildlife. The researchers themselves urged caution, for several reasons.
- Crops are not forests. A field cropped twice a year adds leaf area, but it does not replace the biodiversity, soil carbon or stability of a natural forest.
- Losses elsewhere still count. NASA noted that global greening does not offset the loss of natural vegetation in tropical regions such as Brazil and Indonesia.
- Water is a weak link. India's extra harvests rely heavily on groundwater for irrigation. If aquifers are depleted, the trend could stall or reverse.
- Planting is not the same as survival. Monoculture plantations in dry regions can fail or use scarce water, so the ecological value varies hugely from place to place.
Emissions are a separate question too. China remains the world's largest emitter of greenhouse gases, largely from coal, so more trees in China do not cancel out what its power plants release.
What scientists thought before
When Myneni and colleagues first spotted a greening trend in satellite data in the mid-1990s, the leading explanations were natural: a warmer, wetter climate in some regions and "CO2 fertilisation", where extra carbon dioxide helps plants grow. Those effects are real. What the long MODIS record added was evidence that direct human choices about land, in particular forests and farming, are also a major driver.
That is the hopeful part. Rama Nemani summed it up by observing that people "tend to fix" a problem once they recognise it, pointing to how vegetation loss in China and India in the 1970s and 1980s was followed by recovery once it was taken seriously.
Unbelievable: #Oasis emerges in hinterland of China's largest desert, thanks to three decades of greening pic.twitter.com/SlgUp3RtVj
— China Xinhua News (@XHNews) September 27, 2018
How to read greening maps yourself
When you see a striking green map, ask three questions: what is growing there (forest, crops or grassland), how long it is likely to last, and what it costs in water and lost habitat. NASA's Earth Observatory and the original paper are good places to start, and comparing greening maps with land-use maps usually explains far more than the colour alone.
The lesson from China and India is not that the planet is fine. It is that deliberate policy can visibly change a landscape within two decades, for better or for worse, and that measuring the result honestly matters as much as planting.
Sources: NASA Earth Observatory: China and India lead the way in greening; Chen et al., Nature Sustainability (2019); Wikipedia: Kubuqi Desert. Map and chart: NASA Earth Observatory.
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