Google indexes a number of youth oriented environmental conferences all over the United States. Check out what's available in your part of the country.
An example conference is one sponsored by George Mason University, the National Geographic Society and the National Zoo. They host the annual Washington Youth Summit on the Environment (WYSE). In 2015, WYSE welcomed 250 High School National Youth Delegates from all over the U.S., joining students and faculty from all over the world.
Any student can participate in the YouthCan workshops held at the American Museum of Natural History in New York City via an IRC. Usually held in April, this conference is planned and executed by students. They will demonstrate telecommunications hands-on projects in environmental studies as well as building Web resources.
This activity can serve as a model for student-directed conferences in real and virtual environments which can be replicated at other locales around the world.