This week marks the 50th anniversary of the first Earth Day. A half-century ago, environmental degradation in the United States had reached such an alarming point to so many people that a day was set aside to focus on protecting the planet. In 1990, the April 22 celebration went global and events were organized in countries around the world. The man behind both the creation and expansion of the annual Earth Day is Denis Hayes. KCBX's Greta Mart spoke via Zoom with Hayes, from his office in Seattle in what's considered the world's greenest building.