We use a fully coupled climate-vegetation model to examine the potential effects of changes in vegetation cover on simulations of CO2-induced climate change. We find that vegetation feedbacks, acting mainly through changes in surface albedo, enhance greenhouse warming in the northern high latitudes during spring and summer months. In spring and summer, land surfaces north of 45º N are warmed by 3.3 and 1.7º C by a doubling of CO2 alone; vegetation feedbacks produce an additional warming of between 1.1-1.6 and 0.4-0.5º C, respectively. In winter, however, vegetation feedbacks appear to oppose the 5.6º C radiative warming, particularly over Eurasia. These results demonstrate that vegetation feedbacks are potentially significant and must be included in assessments of anthropogenic climate change.