Journalist and author Moises Velasquez-Manoff talks about the role of dirt in fighting climate change with EconTalk host Russ Roberts. Velasquez-Manoff explains how changes in farming can allow dirt and plants to absorb carbon and potentially reduce climate change. At the end of the conversation he discusses the state of the science on hygiene, parasites, and auto-immune disorders that he discussed in his previous appearance on EconTalk in 2014.