The earth is greener than it was 20 years ago: China and India are the biggest contributors to greening the earth.

Human activities on Earth usually have a negative impact on the environment: dumping plastic into the ocean, melting ice caps at an alarming rate, making polar bears lose their habitat, and so on. But a new satellite data study shows that the earth has become more "green" in the past 20 years or so, with China and India being the biggest contributors.

Since 2000, the global green leaf area has increased by 5%, equivalent to an Amazon rainforest, with China and India contributing 1/3 of the growth. Track the total area of the earth's vegetation cover and its changes over time. Recent satellite data (2000-2017) show that the green belts in China and India are very eye-catching, the study said. "when we first observed the greening of the earth, we thought it was caused by a warmer climate, wetter and increased carbon dioxide in the atmosphere, but through NASA satellite data, we found that humans also contributed.

For example, in China, which dominates the global greening growth, its ambitious tree planting plan and intensive agriculture have made a great contribution to the growth of the green area of the earth. 42% of China's new greening comes from forests and 32% from farmland. In India, on the other hand, as much as 82 per cent of the increase in green plants comes from crops, while only 4.4 per cent comes from new forests.

Part of the reason for China's green effect can be attributed to an ambitious tree-planting plan, the Great Green Wall. In China and India, the vast majority of greening comes from intensive agricultural use of land, which helps feed 1.4 billion and 1.3 billion people in these countries.