Above the Arctic Circle, much of the land is underlaid by permafrost. But climate change is causing it to thaw. This is not good news for the planet.  As the carbon rich ground warms, microbes start to feast… releasing greenhouse gases that will warm the Earth even more. Another possible downside was envisioned by a science-fiction author. Could ancient pathogens–released from the permafrost’s icy grip–cause new pandemics? We investigate what happens when the far north defrosts. Guests: Jacquelyn Gill – Associate professor of paleoecology at the University of Maine. Jim Shepard – Novelist and short story writer, and teacher of English at Williams College, and author of “Phase Six.” Scott Saleska – Global change ecologist, professor of Ecology and Evolutionary Biology at the University of Arizona, and co-founder of IsoGenie.