U.S. Army Staff Sgt. Mitchel Messer, 93rd Signal Brigade retention noncommissioned officer in charge, removes leaves from the Eustis Lake Nature Trail as part of the brigade’s efforts in support of Earth Week at Fort Eustis, Va., April 23, 2013. The celebration of Earth Day began in 1970, when U.S. Senator Gaylord Nelson of Wisconsin introduced the idea for a “national teach-in on the environment,” eventually building a national staff to support his vision nationwide. (U.S. Air Force photo by Airman 1st Class R. Alex Durbin/Released)