If we're going to solve the climate crisis, we need to talk about construction. The four main building materials that humans currently use -- concrete, steel, masonry and wood -- have a heavy environmental impact, but what if we had a fifth option? Architect Michael Green proposes an entirely new, natural medium inspired by the structure of trees and plants. Learn more about the carbon-sequestering solution to our construction conundrum that's laying the groundwork for a truly sustainable future.