This chapter examines ecological science fiction’s (sf) use of terraforming to critique technological climate control as a form of colonial mastery. Terraforming - the adaptation of planetary environments to make them habitable by forms of life from Earth - has long been an important figure in sf and has recently become crucial to its engagement with the climate and climate change. Terraforming narratives portray the complex interpenetrations between the climate, society, culture, science, and politics, and explore how systematic climate control functions as a way to control society and non-human nature. Analysing terraforming in three narratives that have been influential in shaping the motif, Arthur C. Clarke’s The Sands of Mars (1951), Frank Herbert’s Dune (1965), and Kim Stanley Robinson’s Mars trilogy (1992, 1993, 1996), this chapter shows how they highlight the persistence of colonial frontier narratives in shaping representations of interplanetary colonisation, thus connecting terraforming to a tradition of totalising technological mastery over the environment.