New Human Footprint Map
December 2005
According to
the SAGE website, "between 1.5 and 1.8 billion hectares - an area about
the size of
(Dec. 16) Scientists released a new global map of the human "footprint" - indicating which lands people use for growing crops - last week at the annual meeting of the American Geophysical Union in San Francisco.
Humans use more than a third of Earth's land surface for agriculture, according to scientists from the Center for Sustainability and the Global Environment (SAGE) in Madison, Wisconsin.
Navin Ramankutty, a member of the SAGE team, said, "the real question is: how can we continue to produce food from the land while preventing negative environmental consequences such as deforestation, water pollution and soil erosion?"
The SAGE researchers collect data from satellites, censuses, reports of crop yields and other sources and then distill those into global maps. What emerges are views of the "human footprint," the set of places that bear our unique stamp.
The SAGE researchers said that, as world population increases, the percentage of Earth's land surface used for producing food grows.
Watch a video showing how crop lands have expanded from the year 1700 to 2000.
The scale of human agricultural activity makes it one of the central forces of global environmental change.
Some scientists have a broader definition of human footprint, which includes not only lands we actively use for agriculture, but those that are afffected by urban development, road building, pollution, water diversion and so on. In this view, well over 80 percent of Earth is marked by the human footprint.
Earth and Sky has interviewed many experts on the human footprint. Read comments from: Malanding Jaiteh; Daniel Janzen; Ken Caldeira; Carol Brewer; Darron Collins; Felicia Coleman; and Christian Samper.