Ending nuclear weapons before they end us: current challenges and paths to avoiding a public health catastrophe.

The United Nations Treaty on the Prohibition of Nuclear Weapons (TPNW)-an important planetary health good-entered into legal force in January 2021. Evidence of the consequences of nuclear war, particularly the global climatic and nutritional effects of the abrupt ice age conditions from even a relatively small regional nuclear war, indicates that these are more severe than previously thought. None of the nine nuclear-armed states is disarming; instead, all invest enormously in new and more hazardous nuclear weapons. Nor has any of the 32 states claiming reliance on another state's nuclear weapons yet ended such reliance. These factors, abrogation of existing nuclear arms control agreements, policies of first nuclear use and war fighting, growing armed conflicts worldwide, and increasing use of information and cyberwarfare, exacerbate dangers of nuclear war. Evidence-based advocacy by health professionals on the planetary health imperative to eliminate nuclear weapons has never been more urgent.

The nuclear weapons ban treaty and the non-proliferation regime.

The Treaty on the Prohibition of Nuclear Weapons (TPNW), adopted by the United Nations General Assembly in July 2017, has been met with mixed reactions. While supporters have described the Treaty as a watershed in the struggle for disarmament, others have expressed fervent opposition. One of the most serious charges levelled at the TPNW is that it will undermine the long-standing nuclear Non-Proliferation Treaty (NPT), by many regarded as a cornerstone of the international security architecture. Critics have contended that the new agreement risks eroding the system of safeguards designed to prevent the spread of nuclear weapons, derailing disarmament efforts within the NPT framework, and aggravating political division between nuclear and non-nuclear powers. Investigating the legal and political cogency of these arguments, we argue that not only may the TPNW be reconciled with existing legal instruments, the new Treaty supports and reinforces key norms and institutions on which the nuclear non-proliferation and disarmament regime is based. Furthermore, any technical challenges that might arise in the future may be addressed at meetings of states party; the drafters envisioned a dynamic process of institutional adaptations and expansion. The main challenge facing advocates of the Treaty is political: convincing the nuclear-armed states to disarm.