Global tree canopy cover increased by 2.24 million square kilometers (865,000 square miles) between 1982 and 2016, reports a new study in Nature.
Researchers using satellite data tracked the changes in various land covers to find that gains in forest area in the temperate, subtropical, and boreal climatic zones are offsetting declines in the tropics. In addition, forest area is expanding even as areas of bare ground and short vegetation are shrinking. Furthermore, forests in montane regions are expanding as climate warming enables trees to grow higher up on mountains.
Tree canopy in Europe, including European Russia, has increased by 35 percent—the greatest gain among all continents. The researchers attribute much of that increase to the "natural afforestation on abandoned agricultural land," which has been "a common process in Eastern Europe after the collapse of the Soviet Union."
The researchers' satellite data also confirms the effectiveness of China's large-scale reforestation and afforestation programs, leading to a tree canopy gain of 34 percent in that country. Declining forest cover in the western United States, meanwhile, has been offset by increased tree canopy cover in the eastern part of the country. The result is that overall U.S. tree cover increased by 15 percent in the study period.
The study notes that the expansion of the agricultural frontier is the primary driver of deforestation in the tropics. "The three countries with the largest area of net tree cover loss during 1982–2016 are all located in South America: Brazil (?385,000 km2, ?8%), Argentina (?113,000 km2, ?25%) and Paraguay (?79,000 km2, ?34%)," report the researchers.
These new findings contradict earlier studies that reported a continuing net loss of forest cover. For example, the Food and Agriculture Organization's Global Forest Resources Assessment 2015 reported, "In 1990 the world had 4,128 million [hectares] of forest; by 2015 this area had decreased to 3,999 million ha. This is a change from 31.6 percent of global land area in 1990 to 30.6 percent in 2015."
If the Nature study is correct, the world gained 2.24 million square kilometers rather than lost 1.29 million square kilometers in forest area in the past three decades. Expanding woodlands suggests that humanity has begun the process of withdrawing from the natural world which in turn will provide greater scope for other species to rebound and thrive.