The article "Human Appropriation of the Products of Photosynthesis" by Peter M. Vitousek, Paul R. Ehrlich, Anne H. Ehrlich, and Pamela A. Matson estimates the amount of terrestrial net primary production (NPP) that humans have appropriated. NPP is the amount of energy left after subtracting the respiration of primary producers from the total amount of energy fixed by photosynthesis. It is the total food resource on Earth and is used by humans for food, fuel, fiber, and timber. The authors calculate human appropriation of NPP in three ways: a low estimate, an intermediate estimate, and a high estimate. The low estimate is the amount of NPP used directly by humans, while the intermediate estimate includes NPP co-opted by humans, such as that used in human-dominated ecosystems. The high estimate includes potential NPP lost due to human activities, such as land conversion, desertification, and overuse. The low estimate calculates that humans use about 7.2 Pg of organic material directly each year, which is about 3% of the biosphere's total annual NPP. The intermediate estimate calculates that humans co-opt 11.6 Pg of NPP on grazing lands, representing 22.6% of the total annual NPP in woodlands, grasslands, and savannas. The high estimate calculates that humans co-opt 58.1 Pg of NPP on land, representing 40% of potential terrestrial productivity. The authors conclude that humans have appropriated nearly 40% of potential terrestrial productivity, or 25% of the potential global terrestrial and aquatic NPP. This highlights the significant impact of human activities on the biosphere and the need for sustainable practices to ensure the long-term survival of ecosystems and species. The study emphasizes the importance of understanding and managing human impact on the environment to prevent further degradation of natural resources.The article "Human Appropriation of the Products of Photosynthesis" by Peter M. Vitousek, Paul R. Ehrlich, Anne H. Ehrlich, and Pamela A. Matson estimates the amount of terrestrial net primary production (NPP) that humans have appropriated. NPP is the amount of energy left after subtracting the respiration of primary producers from the total amount of energy fixed by photosynthesis. It is the total food resource on Earth and is used by humans for food, fuel, fiber, and timber. The authors calculate human appropriation of NPP in three ways: a low estimate, an intermediate estimate, and a high estimate. The low estimate is the amount of NPP used directly by humans, while the intermediate estimate includes NPP co-opted by humans, such as that used in human-dominated ecosystems. The high estimate includes potential NPP lost due to human activities, such as land conversion, desertification, and overuse. The low estimate calculates that humans use about 7.2 Pg of organic material directly each year, which is about 3% of the biosphere's total annual NPP. The intermediate estimate calculates that humans co-opt 11.6 Pg of NPP on grazing lands, representing 22.6% of the total annual NPP in woodlands, grasslands, and savannas. The high estimate calculates that humans co-opt 58.1 Pg of NPP on land, representing 40% of potential terrestrial productivity. The authors conclude that humans have appropriated nearly 40% of potential terrestrial productivity, or 25% of the potential global terrestrial and aquatic NPP. This highlights the significant impact of human activities on the biosphere and the need for sustainable practices to ensure the long-term survival of ecosystems and species. The study emphasizes the importance of understanding and managing human impact on the environment to prevent further degradation of natural resources.