The study published in the journal 'Nature Sustainability' said that recent satellite data reveals a greening pattern that is strikingly prominent in China and India and overlaps with croplands world-wide.
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.
"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.
Land area used to grow crops is comparable in China and India – more than 770,000 square miles – and has not changed much since the early 2000s. Yet these regions have greatly increased both their annual total green leaf area and their food production.
This was achieved through multiple cropping practices, where a field is replanted to produce another harvest several times a year. Production of grains, vegetables, fruits and more have increased by about 35-40% since 2000 to feed their large populations.