How should we bend the curve of biodiversity loss to build a just and sustainable future?

Current rates of habitat and biodiversity loss, and the threat they pose to ecological and economic productivity, would be considered a global emergency even if they were not occurring during a period of rapid anthropogenic climate change. Diversity at all levels of biological organization, both within and among species, and across genomes and communities, is critical for the resilience of the world's ecosystems in the face of such change. However, it remains an urgent scientific challenge to understand how biodiversity underpins these ecological outputs, how patterns of biodiversity are being affected by current threats, and how and where such biodiversity contributes most directly to human economies, well-being and social justice. In addition, even with such scientific understanding, there is a pressing need for societies to incorporate biodiversity protection into their economies and governance, and to stop subsidizing the loss of humanity's future prosperity for short-term private benefit. We highlight key issues and ways forward in these areas, inspired by the research and career of Dame Georgina Mace FRS, and by our discussions during the Royal Society meeting of June 2023.This article is part of the discussion meeting issue 'Bending the curve towards nature recovery: building on Georgina Mace's legacy for a biodiverse future'.