Global warming is significantly altering the environmental conditions in which forests grow at a global scale. At the local scale, the impact of global warming on forests depends heavily on current forest type and structure, soil conditions and water availability (Figure 1). Managing forests for the provision of ecosystem services requires anticipating how global warming might alter local environmental conditions and how this will affect the forests. Based on this anticipation, measures can be taken to reduce the risks and support forests in their adaption to those anticipated conditions. Such measures should take into account uncertainties and the effect that those measures themselves will have on climatic and other environmental conditions. This chapter aims to contribute to this process by summarizing the current state of knowledge on the interactions between forest ecosystems and the climate system and the way in which forests influence the water cycle.