This Element provides an accessible introduction to ecosemiotics and demonstrates its pertinence for the study of today's unstable culture-nature relations. Ecosemiotics can be defined as the study of sign processes responsible for ecological phenomena. The arguments in this Element are developed in three steps that take inspiration from both humanities and biological sciences: 1) Showing the diversity, reach and effects of sign-mediated relations in the natural environment from the level of a single individual up the functioning of the ecosystem. 2) Demonstrating numerous ways in which prelinguistic semiotic relations are part of culture and identifying detrimental environmental effects that self-contained and purely symbol-based sign systems, texts and discourses bring along. 3) Demonstrating how ecosemiotic analysis centred on models and modelling can effectively map relations between texts and the natural environment, or the lack thereof, and how this methodology can be used artistically to initiate environmentally friendly cultural forms and practices.