Beyond relative sustainability: A review of absolute environmental sustainability assessment

: Environmental assessment is good at showing which option is better, but often fails to show whether any option is good enough. Absolute Environmental Sustainability Assessment addresses this limitation by comparing environmental impacts with an ecological carrying capacity - including Planetary Boundaries as an Earth-system specification - and, for sub-global assessment objects, with an allocated share of that capacity. This review examines how the field has evolved into a boundary-based assessment framework and synthesizes the literature across three strands: methodological development, allocation of carrying capacities, and case study applications. A systematic literature search was conducted in Scopus and Web of Science using the term “Absolute Environmental Sustainability”, resulting in 110 eligible records published up to 1 April 2026. Each publication was coded according to bibliographic, methodological, spatial, temporal, and thematic characteristics. The results show that the field has developed from early carrying-capacity-based Life Cycle Assessment indicators towards a broader methodological landscape that includes Planetary Boundary-based impact assessment, regional downscaling, ecosystem-service approaches, dynamic and prospective assessment, uncertainty analysis, sufficiency-oriented frameworks, and decision-support applications. Allocation emerges as a central normative issue, because sustainability claims depend not only on ecological limits, but also on how limited environmental space is assigned to countries, sectors, companies, products, or functions. Case studies show that systems improved in relative terms can still exceed allocated ecological budgets. Absolute Environmental Sustainability Assessment should therefore be treated as an evaluative framework for testing compatibility with ecological limits, whose diagnostic and strategic extensions make the distance to those limits visible and guide transformations beyond relative improvement.