Fig. 1. The parasite fauna of Arctic ungulates has been shaped by historical and contemporary processes. Today, the Arctic today is characterized by extremes in temperature, high seasonality, and low host species diversity and abundance. Rapid climate warming is now a dominant feature that is altering host–parasite interactions in several ways. Temperatures directly affect parasite development and survival in the environment and in ectotherm hosts, and although warming temperatures may initially accelerate transmission, they may quickly exceed the upper thermal tolerance limits for some arctic parasites. Using the Metabolic Theory of Ecology, temperature dependencies can be modeled and generalized to provide broader insights across genera and ecological regions. Climate changes may also alter both host and parasite life-history strategies and phenology, including migration patterns, leading to non-linear changes and tipping points in transmission ecology. Climate warming and associated changes in the cryosphere also alters ecological barriers and corridors, leading to range shifts and new contact zones.