Since climate change threatens human wellbeing across the globe and into the future, we require a concept of wellbeing that encompasses an equivalent ambit. This paper argues that only a concept of human need can do the work required. It compares need theory with three alternative approaches. Preference satisfaction theory is criticised on the grounds of subjectivity, epistemic irrationality, endogenous and adaptive preferences, the limitlessness of wants, the absence of moral evaluation, and the non-specificity of future preferences. The happiness approach is found equally wanting. The main section shows how these deficiencies can be addressed by a coherent theory of need. Human needs are necessary preconditions to avoid serious harm, are universalisable, objective, empirically grounded, non-substitutable and satiable. They are broader than ‘material’ needs since a need for personal autonomy figures in all theoretical accounts. While needs are universal, need satisfiers are most often contextual and relative to institutions and cultures. The satiability and non-substitutability of needs is critical for understanding sustainability. The capability approaches of Sen and Nussbaum are compared but argued to be less fundamental. Finally, human needs provide the only concept that can ground moral obligations across global space and intergenerational time and thus operationalise ‘sustainable welfare’.