Although, Greece is a Mediterranean country where, particular regions of its territory threatened with substantial impacts due to climate change, the academic research and critical reflection on the effects of the environmental and sustainability education initiative are lacking. Several studies, in Greece and worldwide, have been conducted on school students' perceptions, ideas and understanding current environmental issues: climate change, greenhouse effect, and global warming. However, this study is the first that examines how students' environmental knowledge, attitude and behavior develop throughout adolescence and investigates the interaction between students' cognitive level and the Greek official secondary school curriculum. A total of 600 secondary students participated, answering a questionnaire that focused on the students' cognitive level on the environmental issues in relation to the official school curriculum, the influence of socio-demographic characteristics (students' age, gender, school district, parents' educational level), their environmental knowledge and consciousness, the information sources in the construction of their knowledge and awareness, as well as their suggestions for mitigation the environmental problems and finally the school vital role in informing and raising awareness.