From the human footprint map page:
Analysis of the human footprint map indicates that 83% of the land's surface is influenced by one or more of the following factors: human population density greater than 1 person per square kilometer, within 15 km of a road or major river, occupied by urban or agricultural land uses, within 2 km of a settlement or a railway, and/or producing enough light to be visible regularly to a satellite at night. 98% of the areas where it is possible to grow rice, wheat or maize (according to FAO estimates) are similarly influenced. However human influence is not inevitably negative impact -- in fact conservation organizations, including the Wildlife Conservation Society, have shown remarkable solutions that allow people and wildlife to co-exist. Nature is often resilient if given half a chance. Human beings are in the position of offering or withholding that chance.
Wildlife Conservation Society scientists developed the map. On the human footprint map site you can read the story of this project, and view the atlas pages.
Related Link:
National Geographic article on the human footprint map.