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 permafrosts icy grip, cause new pandemics? We investigate what happens when the far north defrosts.