The Doomsday Clock shows we are closer to global catastrophe than ever before - this needs to be a wake-up call for the world

At the start of the second decade of the 21st century, our world faces a security crisis greater even than the heights of the Cold War.

Nuclear annihilation is an acute threat, aggravated by both stand-offs over Iran and the Korean Peninsula, and by the deliberate undoing of arms control agreements that have restrained proliferation by key powers including Russia and the United States.

The climate crisis poses an equally grave existential challenge to humanity, with the devastating fires in Australia only the latest example of the risks posed to human health and safety by global warming and extreme weather events. But even though the last year has seen an outpouring of popular anger and demands for radical change, global leaders have yet to show they are capable of taking the bold steps to cut emissions and deliver a sustainable future.

This is why today The Elders, represented by Mary Robinson and myself, joined the Bulletin of Atomic Scientists in taking the dramatic step of moving forward the hands of the Doomsday Clock. It is now just 100 seconds to midnight – we are closer to global catastrophe than we have ever been before.

This must be a wake-up call for the world. The decision to move the hands of the Doomsday Clock is backed by rigorous scientific scrutiny, and demands an equally rigorous multilateral response.

Recent events in the Middle East have shown how unilateral actions beyond the bounds of international law can spark unpredictable and potentially uncontrollable consequences.

The tragic shooting down of a Ukrainian passenger jet in Tehran, killing 176 civilians, is an awful warning of the price paid in innocent blood when leaders favour bellicose posturing over serious negotiations.

The prospect of a similar confrontation between two or more nuclear-armed powers should horrify us all but is dangerously real, as we saw in 2019 between India and Pakistan over Kashmir. Such tensions call for responsible global leadership and a careful, concerted attempt to strengthen multilateral frameworks around nuclear disarmament and non-proliferation.

The Non-Proliferation Treaty (NPT) Review Conference that will take place later this year in New York is a critical opportunity to make progress, but the current postures of the leading nuclear powers do not augur well. Instead, over the last year we have seen precisely the opposite as the US and Russia have abandoned the Intermediate-Range Nuclear Forces (INF) Treaty, raising the prospect of another dangerous nuclear arms race on European soil.

If the New Strategic Arms Reduction Treaty (START) is not renewed in 2021, there will be no nuclear arms agreement in force between Russia and the United States anymore, and no remaining limits on the size of their deployed nuclear arsenals.

This is a test of leadership. It is encouraging that President Putin has stated clearly that Russia is ready to renew New START without delay, and I urge President Trump to now move without delay to get a deal. Meanwhile, both Washington and Moscow have also continued to invest in new technologies such as hypersonic cruise missiles and space-based systems, with the rapid and opaque nature of technological development further contributing to mutual paranoia and distrust.

All nuclear powers – the five permanent members of the UN Security Council (US, Russia, China, France and the UK) as well as Israel, India, Pakistan and North Korea – need to face up to their responsibilities and work together to reduce their nuclear stockpiles.

The common thread uniting and exacerbating the nuclear and climate threats is the assault on the multilateral rules-based system that has helped underpin global peace and stability since the Second World War. Leaders of that era, including President Franklin D Roosevelt and President Harry S Truman, were determined to avoid the mistakes of the past, when the League of Nations proved powerless in the face of Nazi and fascist aggression.

Yet too many leaders today either embrace the doctrines of nationalism and isolationism, or lack the political courage to challenge these malign forces and instead retreat into passivity. At such a moment, the world should recall the inspiring words of the late Kofi Annan, my predecessor as UN Secretary-General whose life was devoted to the cause of peace:

“When leaders fail to lead, the people will lead and make them follow.”

We have seen this over the last twelve months with the remarkable and inspirational youth climate movement. In a year that marks the 75th anniversary of both the Hiroshima and Nagasaki bombs, and the founding of the UN, we now need a similar global mobilisation against the nuclear threat, so we can bequeath a peaceful, liveable world to our children and grandchildren.

Ban Ki-moon is a former secretary-general of the United Nations and deputy chair of The Elders, the group of independent global leaders founded by Nelson Mandela