In this Open Letter, science associations and networks across Europe hereby express our grave concern over a series of decisions, taken by European decision-makers, that undermine the EU’s environmental agenda and its international obligations. We note that these attacks on the Green Deal jeopardise nature, and risk the future of EU citizens. While EU policymakers claim that the measures are taken in response to farmers’ protests, scientists highlight that the decisions are poorly justified, do not address the problems they are aiming to solve, and at the same time ignore substantive scientific evidence against them. We point especially at the rejection of the Sustainable Use Regulation (SUR), the weakening of basic environmental standards in the Common Agricultural Policy (CAP), halting the approval of the Nature Restoration Law (NRL), the Commission’s proposal for exemptions in the Nitrate Directive, and the Commission’s decision to shelve the Framework for Sustainable Food Systems (FSFS). The science community regards these decisions as poorly justified and dangerous, rolling back environmental standards and regulations, some of which are the result of decades of efforts and strongly supported by science and society. In a period of multiple crises, mostly resulting from breaching planetary boundaries, we find it is unacceptable that European governors opt to worsen the conditions that drive these crises. As scientists, we strongly oppose policy choices that accelerate these avoidable crises. We call for policymakers to set a clear and ambitious agenda for environmental protection and the Green Deal for the post-election era; consult with scientists to avoid acting on the basis of misinformation; take back changes within the CAP; urgently approve the NRL; and avoid further watering down of environmental regulations and policies. We also call on citizens, civil society organisations and political parties to support responsible policymaking that secures a safe(r) future.