Growing private and public concern with the environment is pushing businesses to increase their awareness and action. Using the Nordic bank Nordea as a case study and a Green information systems (IS) organizational response model developed on the basis of extant literature, we investigate how Green IS initiatives become part of a firm's overall strategy and part of the organizational sustainability process. We find that Green IS initiatives are initiated through a bottom‐up process where environmentally concerned individuals identify issues and become Green IS champions. They use their authority and edification skills to promote Green IS to the organizational agenda. If the issue is aligned with the organizational agenda, it receives management's endorsement. The empirical case also shows two types of systemic feedback that can fuel a self‐reinforcing sustainability process. The first type of feedback increases the champion's ability to promote Green IS in the future through authority and edification. The second type leads to the transformation of organizational value through reinforcement and extension. Finally, we identify interrelationships between organizational response processes, where higher‐order response processes, e.g. change of corporate values, function as gatekeepers or pre‐conditions for when and which issues are promoted to the organizational agenda. © 2016 Wiley Publishing Ltd