The college credited with igniting a movement of green initiatives is celebrating Earth Day. To recognize the occasion, Unity College President Stephen Mulkey was the featured Earth Day speaker at the University of Maine, Monday afternoon in Orono. He met with students to discuss his college’s decision to divest from investments in fossil fuels, and also their pursuits of more sustainable living on campus. Mulkey says the issue of climate change is the greatest threat to humanity. Recently Unity College gained national attention for their award winning “TerraHaus” dorm which achieved “Passive House” standards, the most energy efficient building standard in the world.