A novel coronavirus—the type of virus that causes SARS, Middle East Respiratory Syndrome (MERS), and common cold symptoms—has killed 18 people, and sickened more than 600. In response, Chinese officials have quarantined several huge cities, where some 20 million people live. In this segment, Ira talks with epidemiologists Saskia Popescu and Ian Lipkin about what we know about the virus, how it appears to spread, and whether efforts to contain it are effective—or ethical.  Do you know where your drinking water comes from? For more than 40 million people in the Great Lakes Basin, the answer is the abundant waters of Lake Michigan, Ontario, Erie, Huron, or Superior. This winter, the Science Friday Book Club has been reading Dan Egan’s The Death And Life of the Great Lakes, and unpacking the drastic ecological changes facing these bodies of water in the last century and beyond. But what about the changes to the water that might affect people who drink it? And does everyone who lives on the lakes actually have equal access? Great Lakes Now reporter Gary Wilson unpacks some of the threats to clean drinking water faced by the region’s residents, from Flint’s lead pipes to Lake Erie’s algae blooms to shutoffs for those who can’t afford to pay. And Kristi Pullen Fedinick of the Natural Resources Defense Council explains a recent report that connected disproportionate levels of drinking water contamination to communities that are poorer or dominated by people of color—all over the country. Finally, Science Diction host Johanna Mayer explains the origins of the word “mercury,” another pollutant that has plagued the Great Lakes. This week business leaders, celebrities, and government officials from around the world met in Davos, Switzerland—and one of the topics was trees. The Trillion Tree campaign, a collaboration between several of the world’s largest environmental organizations, wants to combat global deforestation around the world But at the same time, work published in the journal Global Change Biology indicates that tree planting can lead to unintended consequences. The researchers found that increased levels of forest can reduce the available water in nearby rivers dramatically, cutting river flow by as much as 23% after five years and 38% after 25 years. The effect of trees on river flow is smaller in drier years than wetter ones. The type of soil conditions also have an effect—trees planted on healthy grassland have a larger impact on river flow than forests on former degraded agricultural land. David Coomes, Director of the University of Cambridge Conservation Research Institute and one of the authors of the paper, joins Ira to talk about the pros and cons of reforestation.