The Alps still comprise the largest natural and semi-natural environments in Central Europe, but even the remotest alpine regions may face drastic changes due to human-induced climate warming. The glaciers of the Alps respond to the ongoing temperature increase of about 1-2°C since the 19th century with a drastic shrinkage. The high mountain vegetation is generally considered to be particularly vulnerable to climate change. Therefore, this vegetation can be used as a sensitive "ecological indicator" for climate change effects. An upward movement of high mountain plants was empirically determined at subnival and nival summits (most of them exceeding 3000 m), but no such evidence is available for the lower vegetation belts. Plants will respond to climate change in different ways even at their upper limits, due to different preferences to topographically determined habitats. This resulted from a transect study with detailed field records and fine-scaled distribution models. In addition, the ecophysiological constitution of alpine and subnival plants, their propagation ability, and their life history will be crucial for vegetation dynamics in future warmer climates. The risks of climate-induced upward migration processes of plants include drastic area losses or even extinction of cryophilous plants, a disintegration of current vegetation patterns, and impacts on the stability of high mountain ecosystems.