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 (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 km2 of cropland (12% of the Earth’s ice-free land surface) and 28.0 (90%
confidence range of 23.6–30.0) million km2 of pasture (22%) in the year 2000.