Living earth double oak3/23/2023 Next, Imhoff requested the Gridded Population of the World (GPW) data set, which provides population numbers and density on a regular latitude-longitude grid, from NASA's Socioeconomic Data and Applications Center (SEDAC). Red and orange indicate areas where human demand outstrips nature’s supply. This map shows the net primary production (NPP) supply versus human demand, with demand as a percentage of supply. “This way, we could double-check what the AVHRR data would have shown in the field with what the consumption statistics indicated was actually used.” Then, we backed out what you would need to see in the field to get those products,” he said. He said, “We divided the consumption statistics into food, both plant- and animal-derived and fiber, including wood, wood-based fuel, and paper. To do that, he turned to statistics from the United Nations Food and Agricultural Organization (FAO) on food and fiber consumption by country, taking the data from 1995 as a typical year that matched the satellite timeline. Imhoff ’s next step was to measure the amount of net primary production that humans use worldwide in an average year, and then tie it to cultural consumption habits. Imhoff said, “This information gave us the planetary supply of plant production on land that is available to humans in an average year.” The model output provided Imhoff and his colleagues with an estimate of the planet’s net primary production. The monthly NDVI data were input to a biophysical model together with temperature, humidity, rainfall, and landcover type. The data were taken every sixteen days from 1982 to 1998, allowing Imhoff to compute an average maximum NDVI for each month of the year. The data, originally from the Advanced Very High Resolution Radiometer (AVHRR) instrument, were reprocessed under the International Satellite Land-Surface Climatology Project to retrieve NDVI. To measure net primary production, Imhoff used Normalized Difference Vegetation Index (NDVI) data, which quantify the presence of healthy vegetation. Plants provide food and fiber, as well as support the animals we use for food and clothing. Human beings rely on our planet’s net primary production for survival. All of our food, much of our fiber, and-for many people in developing countries-fuel for cooking, is derived from plant material.” Imhoff put it this way: “Net primary production is the plant material that we see above ground, as well as what is below ground, like root systems. Net primary production is a measure of plant productivity, the amount of plant material left over after respiration. His findings remind us that we all rely on the same finite Earth. In fact, it goes beyond just need it includes our different lifestyles-our appetites.” To build some answers, Imhoff set about measuring global plant productivity, calculating human consumption levels on a cultural level, and then comparing what he learned. He said, “Our primary motivation has been to find out where we stand relative to our survival on the planet, and what our needs are compared to the capability of the biosphere to sustain them. Marc Imhoff, a biophysical scientist with NASA, has been exploring these questions with colleagues from the University of Maryland’s Earth System Science Interdisciplinary Center, the World Wildlife Fund, and the International Food Policy Research Institute for six years. But as global population and incomes rise, will plants be able to keep up with the human appetite? And if they cannot, which regions will be short on food and other plant-based resources, and what will that mean for nations as they try to assure food security for their citizens? Plants turn the energy of the sun into our most basic needs: lumber for houses, fuel for cooking, fiber for clothing, feed for livestock, and food for our own growing bodies.
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