The pedagogical methods and techniques used in teacher training programs are important tools to graduate qualified teachers. Argumentation, which is known as evidence based scientific discussions, is one of the most widely used tools in national and international literature. The aim of the present study is to explore the quality of Preservice Science Teachers (PSTs) scientific reports those were written by using online course documents regarding the climate change issue. The qualitative research method guided the present study. The effects of climate change on the Earth were explored in four sub-dimensions which are; glacier melting, drought, disasters and immigrations, endangered species. In order to examine the PST's nature of written argumentation, a rubric, developed by Kelly, Regev, and Prothero (2007), was used. The results of this study indicate that, PSTs' written argumentation tends to improve. The current study provides an initial picture of the argumentation writing practices of PSTs.