Diamond is the new Green—Why Green Open Access is not a sustainable long-term model for scientific publishing

In recent decades, the academic publishing world has aimed to transition from a paywall-dominated system to Open Access (OA). While OA seeks to make scientific knowledge freely available, the sustainability of current models remains debated. This article examines the three main OA publishing routes (Green, Gold and Diamond) and argues that, while Green OA offers short-term accessibility benefits, it perpetuates dependence upon for-profit publishers and fails to address systemic inequities. Gold OA shifts financial responsibility to authors through high article processing charges (APC), further exacerbating disparities. In contrast, Diamond OA, driven by community-led initiatives and supported by open infrastructures, eliminates APC, ensures equitable access, and allows authors to share their work freely. We highlight successful examples in geosciences and discuss the cultural and structural barriers that still hinder adoption, despite Diamond OA representing the most sustainable, fair and accessible long-term model for scholarly publishing.