Evidence is indisputable that any use of such weapons would have a devastating health impact on populations. Robust scientific studies show that even a limited exchange of nuclear weapons would lead to major crop failures around the world. Such a “nuclear famine” scenario would result in mass starvation, potentially affecting as many as 2 billion people.

Live – North Korea claims test of ‘missile-ready’ nuclear bomb – live US and South Korean security chiefs hold emergency talks as hydrogen bomb test puts Pyongyang closer to developing warhead On 20 September, countries commence signing the comprehensive treaty banning nuclear weapons adopted on 7 July 2017 at the UN. The treaty to prohibit nuclear weapons agreed by 122 nations finally gives these weapons of mass destruction a similar legal status to biological and chemical weapons.

The treaty prohibits signatories from: preparation of nuclear weapons, actual use, and assisting other states or non-state groups in such actions. The UK, alongside other nuclear-armed states, boycotted the negotiations, despite government claims to support multilateral disarmament and despite polling indicating that 75% of the UK population supported UK government participation.

It is not too late for the position of the British government to change. Possession of nuclear weapons undermines a potential leadership role for the UK to enhance security and stability in the world.

We call upon the British government to immediately begin the process of joining the treaty. As a first step, it could reduce its threatening nuclear posture, specifically by abandoning its “first-use policy” and ending continuous nuclear-armed patrols – both of which increase the risk of nuclear war”.

Dr Michael Orgel Medact Scotland

Dr Stuart Parkinson Executive director, Scientists for Global Responsibility

Dr Philip Webber Chair, Scientists for Global Responsibility

Dr Ira Helfand Co-president, International Physicians for the Prevention of Nuclear War and recipient of the 1985 Nobel peace prize

Professor Peter Ware Higgs Nobel laureate physics

Professor David McCoy Director, Medact UK

Professor Alan Robock Rutgers University, New Brunswick, New Jersey, USA

Professor John CM Gillies

Dr Judith McDonald Medact Scotland

Dr Lesley Morrison Medact Scotland

Professor David Webb

Professor Malcolm Povey University of Leeds

Dr Margaret McCartney GP, Glasgow

Dr Guy Johnson Medact Scotland