Understanding the public opinion's awareness and knowledge of climate change is very important for three reasons. First, because public opinion has a key role in influencing the strategies of governments and firms. Second, because the superspecialised engineering approach can be successfully integrated by the psychosocial perspective. Third, because in order to build consent around the theme of climate change one must determine the public's awareness of this problem. The article describes the contribution of two approaches developed by the social sciences: the qualitative study of the approach based on surveys, and the qualitative analysis of everyday speech. The results obtained from both are strongly influenced by the type of tools used to collect the data. The two approaches presented are very different and are sometimes considered self-sufficient, alternative or complementary. The process of building consent, which the scientific community should pursue, is thus shown to be a rather complex matter.