Ice is melting worldwide at unprecedented rates, which is releasing enormous amounts of viable microbes, including pathogens. Several modern virus diseases exhibit patterns of appearance, disappearance, and reappearance that cannot be completely explained. Most viruses survive freezing and thawing, and we have found viruses in ice cores from Greenland and Antarctica. Therefore, it is possible that some of these disease reappearances can be explained by viruses melting from glaciers and then infecting susceptible hosts. Influenza A, caliciviruses, rotaviruses, and others may follow this pattern, and most survive freezing and thawing. Additionally, other viruses, thought to be extinct, may be able to reemerge.