Sustainable AI isn't greenwashing — it's strategic resilience . Model choice impacts energy costs, carbon footprint, regulatory compliance, and social trust over years, not quarters. Key sustainability lenses: Inference efficiency (smaller models = lower operational carbon) Training footprint (pre-trained vs. from-scratch) Responsible agency (bias detection, explainability, moral alignment) Scalability (infra costs as usage 10x's) Real-world proof: Google's DeepMind opti