Land transformation by humans: A review

In recent decades, changes that human activities have wrought in Earth’s life support system have worried many people. The human population has doubled in the past 40 years and is projected to increase by the same amount again in the next 40. The expansion of infrastructure and agriculture necessitated by this population growth has quickened the pace of land transformation and degradation. We estimate that humans have modified >50% of Earth’s land surface. The current rate of land transformation, particularly of agricultural land, is unsustainable. We need a lively public discussion of the problems resulting from population pressures and the resulting land degradation.