The most recent report from the Intergovernmental Panel of Climate Changes, IPCC (2007), shows less uncertainty related to the climate changes which have been pointed out for decades. This article presents, therefore, a discussion about possible effects of global environmental changes, resulting from climate change, on certain aspects of demographical dynamics. What becomes evident is that these environmental changes tend to potentialize changes in mortality and morbidity rates as well as create situations that demand the reallocation of population groups with repercussions in the spatial redistribution of the population. The data was researched from an analytical perspective of the studies of the relation between population and environment, considering two spatial levels: global and national. One of the emphasized aspects is that if the global environmental changes happen in a short period of time, they may increase the social vulnerability of social groups in worst economical situation, due to an increase in the already existing risk factors.