Climate change is an issue of huge social and academic interest. We approach it from the perspective of local government and its work toward environmental sustainability. The thesis is a comparative study where we examine the environmental policies between two Swedish cities, namely Gävle and Trollhättan, and investigate how these have changed in two specific time periods, 2009 and 2019. The time frame and the choice of cities are motivated by the drastic change in their environmental ranking placement. Through the lens of social constructivism and the theory of What's the Problem Represented to be, created by Carol Bacchi, we can analyse the cities' environmental policies critically. It gives us a comprehensive understanding of how a given policy issue is constructed as a problem. The chosen material for this study consists of formal documents issued by the two municipalities, which are analysed qualitatively. This study concludes that having a narrow and consistent definition of environmental sustainability over time has allowed Gävle to refine its environmental goals, hence the city can prioritize their environmental policies and become a leader in the ranking. While Trollhättan has changed their definition of environmental sustainability between the years 2009 and 2019 toward a multi-dimensional concept of sustainability, including social and economic sustainability. This alteration in policy formulation might be behind Trollhättan's drastic drop in the placement in the environmental ranking. The causal link, however, needs to be further confirmed in future studies.