Context: Many publications have described, measured, tracked or assessed Information and Communication Technology (ICT) activities that impact the environment. A complete conceptual view of the environmental impact of ICT can be described in three orders of effect: Direct, indirect and systemic. Objective: The goal of this study is to find out how the existing literature contributes towards our understanding of the environmental impact of ICT. We approach this question by identifying factors that can be of influence on the environmental impact and map these factors onto a conceptual framework of Green ICT. Method: We used a systematic literature review to collect factors of influence regarding the environmental impact of ICT. Results: From the data we collected and the analyses made, we created a taxonomy, and report on the frequencies of the factors of influence in the primary studies as well as gaps and additions compared to the conceptual framework. We found five main classes of influence that can form a continuous cycle, but noted that the research field is strongly focused on the direct impact of ICT. Conclusion: Our study contributes towards a better understanding of the environmental impact of ICT by framing factors of influence in a conceptual framework. The taxonomy we create and the analysis of the studies could be helpful in defining a research agenda, to further enable the full potential of Green ICT. In addition, the taxonomy can be used as a starting point for a practical tool, for organizations that wish to apply Green ICT to its full extent.