Co2Collar is a piece of critical design that adresses the climatechange. As the title suggests, the concept is a neck collar designed for people to wear. The collar tightens around ones neck according to the average CO2 emission level in the world. Since its CO2 measurements are not local based but universal, it doesn't matter if you live in a country with high or low emissions. Thus the users of these collars become dependent on each other, and signals the common responsibility we have for each other and our planet. Other than creating this relationship, Co2Collar also materializes the otherwise immaterial CO2 emission, and its pragmatic function also gives a new understanding of the unknown time perspectives.