Plant ecosystems and processes at tree-line and in alpine tundra areas very likely are not in equilibrium with the present climate, rather a lag-period of years to decades is expected in their response to climate change. Based on the observed altitudinal temperature lapse rate of 0.7 C per 100 m, we estimate that a regional warming of 2 C would result in a potential upward shift in treeline of about 280 m and consequent substantial loss of tundra area. Preliminary modeling of vegetation in response to climate warming scenarios for the mid-century period (ca. 2040-2069) shows a significantly large increase in the area covered by forest and coniferous shrub, with a corresponding decrease in tundra-heath. By the end of the century, very little tundra or heath is projected to remain at even the highest elevations, with consequent loss of habitat for those plant and animal species that are associated with alpine areas.