Earth in Peril

Human Transformation of Land, late 1990s
According to the U.N. Food and Agriculture Organization, humans have altered approximately half of all the land on Earth for our own uses—around 22 percent for farming and forestry combined, 26 percent for pasture areas, and 2 to 3 percent for housing, industry, and roads. Population growth will necessitate further conversion of land, which in some regions can interfere with natural defenses against flooding, landslides, and erosion. Furthermore, experts believe that the abundance of agricultural topsoil on which our food supply depends is sharply diminishing due to overuse, urbanization, and other human-induced factors.