India and China are leading the way in greening lands, thanks to ambitious tree-planting programs and intensive agriculture in both countries, NASA satellite data has shown.

The world is getting literally greener than it was 20 years ago, the study published in the latest edition in Nature Sustainability on Monday said.

It showed that at least 25 per cent of the global foliage expansion since the early 2000s came from China, with India close behind.

This surprising new development detected by NASA satellites showed that the two nations with the world’s biggest populations were leading the way with their ambitious tree planting programs and intensive agriculture.

In 2017 alone, India broke its own world record for the most trees planted after volunteers gathered to plant 66 million saplings in just 12 hours.

The greening phenomenon was first detected in the mid-1990s, but they did not know whether human activity was one of its chief, direct causes, said researchers from the Boston University, who found that the greenery increase in the new century has been by five per cent — an area equivalent to the entire Amazon rainforest.

Rama Nemani, a research scientist at NASA’s Ames Research Center and a co-author of the study said: “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.”

But with data from NASA’s Terra and Aqua satellites, scientists realised that humans are also contributing. “Humans are incredibly resilient. That’s what we see in the satellite data,” said Nemani.

“China and India account for one-third of the greening, but contain only nine per cent of the planet’s land area,” said lead author Chen Chi of Boston University.

“That is a surprising finding, considering the general notion of land degradation in populous countries from over-exploitation,” said Chen.