This study aimed to identify the erroneous knowledge and misconceptions of preservice elementary teachers about global warming and examine the effects of instruction with visual materials on rectifying these misconceptions and fostering a positive attitude towards the issue of global warming. Having a quasi-experimental design, the study made use of both quantitative and qualitative research methods. The participants of the study, which was conducted in 2008-2009 academic year in Giresun University's Education Faculty, were 47 preservice elementary teachers. Data were obtained by using open ended questions, the Global Warming Attitude Scale (GWAS) and semi-structured interview forms. The results showed that both experimental and control group individuals had knowledge gaps and certain misconceptions about the reasons underlying global warming. However, preservice teachers were more successful in rectifying the gaps and misconceptions via instruction with visual materials. After the intervention, the experimental group had higher global warming attitude scores. However, no meaningful relationship existed between the groups with respect to their attitude scores. (Contains 7 tables and 1 note.)