Today marks the 50th Earth Day in the United States, which traces its origins to Ann Arbor. Normally, there would have been a huge celebration, but the coronavirus pandemic has put a halt to that. For Part 2 of a special, Earth Day edition of "Issues of the Environment," WEMU's David Fair spoke with Jonathan Overpeck, dean of the U-M School for Environment and Sustainability. They discuss an online celebration of Earth Day and look ahead to what the future may hold.