Ramankutty, N, Evan, AT, Monfreda, C, Foley, JA (2008). Farming the planet: 1. Geographic distribution of global agricultural lands in the year 2000. GLOBAL BIOGEOCHEMICAL CYCLES, 22(1), GB1003.
Agricultural activities have dramatically altered our planet's land surface. To understand the extent and spatial distribution of these changes, we have developed a new global data set of croplands and pastures circa 2000 by combining agricultural inventory data and satellite-derived land cover data. The agricultural inventory data, with much greater spatial detail than previously available, is used to train a land cover classification data set obtained by merging two different satellite-derived products (Boston University's MODIS-derived land cover product and the GLC2000 data set). Our data are presented at 5 min (similar to 10 km) spatial resolution in longitude by longitude, have greater accuracy than previously available, and for the first time include statistical confidence intervals on the estimates. According to the data, there were 15.0 (90% confidence range of 12.2-17.1) million km 2 of cropland (12% of the Earth's ice-free land surface) and 28.0 (90% confidence range of 23.6-30.0) million km 2 of pasture (22%) in the year 2000.