Bringing a sustainable population of Atlantic salmon (Salmo salar) back into the Rhine, after the species became extinct in the 1950s, is an important environmental ambition with efforts made both by governments and civil society. Our analysis finds a significant risk of failure of salmon reintroduction because of projected increases in water temperatures in a changing climate. This suggests a need to rethink the current salmon reintroduction ambitions or to start developing adaptive action. The paper shows that the moment at which salmon reintroduction may fail due to climate change can only be approximated because of inherent uncertainties in the interaction between salmon and its environment. The added value of the assessment presented in this paper is that it provides researchers with a set of questions that are useful from a policy perspective (by focusing on the feasibility of a concrete policy ambition under climate change). Thus, it offers opportunities to supply policy makers with practical insight in the relevance of climate change.