A global map of the human appropriation of net primary productivity (HANPP) was divided by a global map of net primary productivity (NPP) to come up with an estimate of HANPP as a Percent of NPP per quarter-degree grid cell. To construct the estimated NPP map (the amount of carbon produced by ecosystems per quarter-degree grid cell), the authors used the Carnegie Ames Stanford Approach carbon model. The model incorporates satellite and climate data to estimate the fixation and release of carbon based on a spatially and temporally resolved prediction of NPP in a steady state. To construct the HANPP map (the amount of carbon required to derive food and fibre products consumed by humans - including organic matter that is lost during harvesting and processing), the authors utilized data from the Food and Agriculture Organization of the United Nations (FAO) on products consumed in 1995 for 230 countries in seven categories: vegetal foods, meat, milk, eggs, wood, paper, and fiber. All calculations use the "domestic supply" quantity for all FAOSTAT country-level sums (i.e., production in country + imports - exports). This constrains the country-level estimate of NPP required to only those products that are consumed within a country's boundaries. To these data they applied harvest, processing, and efficiency multipliers, as well as estimates of below-ground production, to reconstruct the total amount of NPP required to derive final products. They then calculated the per capita HANPP of each country and applied these values to SEDAC's Gridded Population of the World v.2 (GPW) resampled to correspond to the quarter-degree spatial resolution of the NPP data. The method assumes a homogenous per capita consumption rate within each country, which although obviously incorrect, represents a starting point. The authors note that terrestrial HANPP does not directly capture other forms of environmental impact, such as freshwater abstraction, use of fossil fuels, pollutant emissions, and appropriation of NPP from freshwater and marine systems. Finally, unlike earlier studies, the authors did not include the components of NPP that are lost due to land transformations (e.g. shifting cultivation and land clearing for development). For more information, a detailed description of the methods utilized to produce these data is provided in the journal articles in the Source Citation.