For an environmental scientist who studies how humanity is pushing the earth close to potentially disastrous tipping points, Johan Rockström — author Johan Rockström of a new book, Big World, Small Planet — is surprisingly optimistic. Although he reckons that our species has crossed four of nine “planetary boundaries,” including those on climate change and deforestation, he believes there is still time to pull back from the brink and create a sustainable future based on renewable energy and a “circular” economy that continually reuses resources. In an interview with Yale Environment 360, Rockström describes how an alignment of science, technological advances, and a growing public hunger for action can get civilization back on track. “It’s not a journey where we are backing into the caves,” says Rockström. “It’s a journey of high technology … and huge, multiple benefits.” Read the interview.