India and China are leading the global greening effort, a latest NASA study said, observing that the world is a greener place than it was 20 years ago.

India and China are leading the global greening effort, which is quite contrary to the general perception worldwide, a latest NASA study said Monday, observing that the world is a greener place than it was 20 years ago.

The effect comes mostly from ambitious tree-planting programs in China and intensive agriculture in both countries.

"China and India account for one-third of the greening, but contain only 9 per cent of the planet's land area covered in vegetation," said lead author Chi Chen of Boston University."

"That is a surprising finding, considering the general notion of land degradation in populous countries from overexploitation," added Chen.

Findings of the study

1. The study published in the journal 'Nature Sustainability' said that recent satellite data reveal a greening pattern that is strikingly prominent in China and India and overlaps with croplands worldwide.

2. China alone accounts for 25 per cent of the global net increase in leaf area with only 6.6 per cent of global vegetated area.

Trend in annual average leaf area (2000-2017)(Image: earthobservatory.nasa.gov)

3. The greening in China is from forests (42 per cent) and croplands (32 per cent), but in India, it is mostly from croplands (82 per cent) with minor contribution from forests (4.4 per cent).

4. Overall, one-third of Earth's vegetated lands are greening, while 5 per cent are growing browner.

India and China leading the way

China and India lead in greening due to human activity.(Image: earthobservatory.nasa.gov)

China's outsized contribution to the global greening trend comes in large part from its programs to conserve and expand forests with the goal of mitigating land degradation, air pollution, and climate change.

Food production in China and India has increased by over 35 per cent since 2000 mostly owing to an increase in the harvested area through multiple cropping facilitated by fertiliser use and surface and/or groundwater irrigation.

Research methodology

This study was made possible due to a two-decade-long data record from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA's Terra and Aqua satellites.

MODIS provides intensive coverage in space and time. The sensors have captured up to four shots of nearly every place on Earth, every day, for the past 20 years.

"When the greening of the Earth was first observed, we thought it was due to a warmer, wetter climate and fertilization from the added carbon dioxide in the atmosphere. Now with the MODIS data, we see that humans are also contributing," said Rama Nemani, research scientist at NASA's Ames Research Center and co-author of the study.

"Once people realize there is a problem, they tend to fix it. 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," added Nemani.

Greening trend may change in future

According to the paper, how the greening trend may change in the future depends on numerous factors. For example, increased food production in India is facilitated by groundwater irrigation. If the groundwater is depleted, this trend may change.

The researchers also pointed out that the gain in greenness around the world does not necessarily offset the loss of natural vegetation in tropical regions such as Brazil and Indonesia.

There are consequences for sustainability and biodiversity in those ecosystems beyond the simple greenness of the landscape.

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