In 1981, China began planting billions of trees to restore degraded land. Decades later, the 78-billion-tree effort produced a surprising outcome: it altered the water cycle, sending more rain to some regions while drying out others

China’s decades-long reforestation campaign has dramatically expanded vegetation across the country, including through the Three-North Shelterbelt, or “The Great Green Wall.” According to Reuters, China added about 116,000 square miles of trees, while forest coverage increased substantially. However, a 2025 study in Earth’s Future found that the transformation has also affected China’s hydrology.