The boundary region between the boreal forest and tundra is one of the most important vegetation transitions on our planet. It is subject to disturbance over a wide range of spatial and temporal scales, and it is particularly sensitive to these disturbances. Because of its size, remoteness and generally poor accessibility it is particularly favoured as the subject of spaceborne remote sensing observations. In this talk I will discuss the basis of our confidence in the use of satellite remote sensing methods, identify some of the present-day challenges, and suggest how new technologies are helping to overcome them.