Data practices are at the heart of contemporary understandings of environmental change, yet the infrastructures that underpin them are also increasingly understood to have their own significant environmental impacts. In this chapter, contributors address the relationship between data and the environment, by exploring environmental sensing practices, data-driven representations of climate change, and the environmental impacts of data centres. In the contributions, we are interested in the different entanglements of data and the environment, and how power dynamics come into play along the journey from environmental sensing practices, through to data modelling and representation, and data storage and processing in data centres. Across each of the chapter sections, co-authors variously engage with the contours of data, their diverse physical manifestations, their representations, their affects, and the epistemologies they materialize, reproduce, and map onto in environmental and planetary contexts. We ask: how does ‘environmental data power’ as a concept that encompasses all of these practices and contexts operate across each of these registers? To answer this question, we articulate not only how data power takes shape in relation to and via environmental contexts, but also how data technologies, economies, and practices organize and make legible the planetary through these particular affects, epistemologies, and geographies.