The intuitive and logical answer to the question of how the tundra-taiga interface will react to global warming is that it should move north and this is mirrored by many models of potential treeline migration. Northward movement may be the eventual outcome if climatic warming persists over centuries or millennia. However, closer examination of the tundra-taiga interface across its circumpolar extent reveals a more complex situation. The regional climatic history of the tundra-taiga interface is highly varied, and consequently it is to be expected that the forest tundra boundary zone will respond differently to climate change depending on local variations in climate, evolutionary history, soil development, and hydrology. Investigations reveal considerable stability at present in the position of the treeline and while there may be a long-term advance northwards there are oceanic regions where climatic warming may result in a retreat southwards due to increased bog development. Reinforcing this trend is an increasing human impact, particularly in the forest tundra of Russia, which forces the limit of the forested areas southwards. Local variations will therefore require continued observation and research, as they will be of considerable importance economically as well as for ecology and conservation.