In recent years, a growing body of literature on degrowth has compellingly identified limitations involved in decoupling economic growth from its environmental impacts. Despite this, the institutions governing the global environment continue to pursue “green growth” principles. In this article, we showcase how global environmental governance might differ if the degrowth critique were taken more seriously. We use the United Nations–based Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) to illustrate how a multilateral environmental agreement (MEA) might differ if its foundational premises were centered on degrowth as opposed to green growth. To do this, we develop a conceptual scaffold to support the construction of a degrowth-centered MEA on sustainable global aviation. While a degrowth alternative to CORSIA is admittedly unlikely given contemporary capitalist norms in global environmental governance, our proposed scaffold nevertheless adds to the growing body of work envisioning alternative scenarios for a just and sustainable postgrowth future.