Natural Resource Ecology & Management: Non-profits/Think Tanks
WorldWatch Institute - Excellent source for coverage of world environmental challenges. They work to accelerate the transition to a sustainable world that meets human needs and publish State of the World and Vital Signs.
Pew Research Center - The Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping America and the world. Their section on Energy and Environment is relevant.