Attendees of Apple's 2012 World Wide Developers Conference look at the new MacBook Pro with Retina display. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

GED = gross external damages from pollution.

Environmental Accounting for Pollution hide caption

itoggle caption Environmental Accounting for Pollution

Early morning view of an automated irrigation system in on a farm in Sudlersville, MD

Cliff Owen/AP hide caption

itoggle caption Cliff Owen/AP