Recent surveys have shown that a significant percentage of young adults in the U.S. are disengaged or disagree with the fact that human activity is the cause of the issue of global warming. Yet, the National Academy of Sciences has published studies showing strong scientific evidences for global warming due to increasing human energy consumption of fossil fuels. Accordingly, the United Nations Educational, Scientific, and Cultural Organization (UNESCO) published learning objectives for educating the world population on global warming and renewable energy by 2030. In this paper, we introduce how physics educators can employ reflective writing to foster deeper student understanding of global warming in introductory college physics and physical science courses, without overloading teaching time.