Eighty years ago, in the early morning of August 6, 1945, a US B-29 bomber took off from Tinian, the Northern Mariana Islands. At 8.15 am, the new type of bomb it was carrying exploded nearly 600 metres above the city.

Within the first few seconds, a 300-metre fireball began consuming everything in its path. The searing fireball escalated temperatures on the ground to more than 3800°C, vaporising every bit of living tissue.

The bomb’s blast wave crushed buildings in every direction. Gases burned by the fireball created a massive vacuum, and dust and debris rushed in to fill the space. A spindly mushroom cloud rose over the now flattened city of Hiroshima.

Within minutes, 80,000 people died from the first nuclear weapon ever used in warfare. Hundreds of thousands more died from its impact over the coming months. The second attack, on Nagasaki three days later, led to the deaths of 100,000 more. At least 38,000 of the dead were infants and children. 

A survivor’s warning 

Yet, below the mushroom clouds, not everyone was killed. Survivors like Setsuko Thurlow, who was 13 years old when the US bombed Hiroshima, have spent decades telling the world about what nuclear weapons actually do, in an effort to make sure they are never used again. Delivering the 2017 Nobel Peace Prize lecture, Setsuko described her experience:

"As I crawled out, the ruins were on fire. Most of my classmates in that building were burned to death alive. I saw all around me utter, unimaginable devastation.

“Processions of ghostly figures shuffled by.  Grotesquely wounded people, they were bleeding, burnt, blackened, and swollen. Parts of their bodies were missing. Flesh and skin hung from their bones. Some with their eyeballs hanging in their hands. Some with their bellies burst open, their intestines hanging out. 

“The foul stench of burnt human flesh filled the air. Thus, with one bomb, my beloved city was obliterated.”

The stories of what happens when nuclear weapons, painful as they are for survivors to recount, are a necessary reminder that these bombs are designed to cause massive harm. Weapons designed to incinerate a city.

The bombs dropped by the US on Hiroshima and Nagasaki were a fraction of the size of those in today’s arsenals. The Nuclear Ban Monitor estimates that the current collective explosive yield of the 9,604 nuclear warheads available for use at the beginning of 2025 is equal to the yield of more than 146,500 Hiroshima bombs. 

Each bomb with the power to wipe out a city in seconds, to kill tens of thousands in a fiery flash. With a near majority of the global population living in more than 11 thousand cities worldwide, there are more than enough nuclear weapons ready for use to destroy life as we know it.

The US attacks on Hiroshima and Nagasaki, following the first nuclear detonation in New Mexico a few weeks before, showed that nuclear weapons cannot be used without causing catastrophic intergenerational harm, and that these weapons violate the basic dictates of public conscience and fundamental human rights. 

80 years of living under the existential threat of nuclear weapons is enough, and the need to eliminate them is urgent.

The threat that nuclear weapons could be used again, either by accident or intentionally, is as high as it has ever been – and perhaps even higher – driven by the nuclear tensions over Ukraine and in the Middle East, as well as between India and Pakistan, and on the Korean peninsula. 

The survivors of Hiroshima and Nagasaki, the hibakusha, have campaigned for decades for the abolition of nuclear weapons, and last December the All Japan Confederation of A- and H-bomb Sufferers Organizations, Nihon Hidankyo, was awarded the Nobel Peace Prize in recognition of this work. 

The time is now 

The 80th anniversary of the events that changed their lives forever is the right moment for the leaders of nuclear-armed countries, who congratulated them on their Nobel, to follow through on their words and do what the hibakusha have called on them to do - join the UN Treaty on the Prohibition of Nuclear Weapons (TPNW) and disarm. 

The TPNW is steadily growing in strength - half the world’s countries have now signed or ratified it, and more will soon follow.

These countries reject the illusory and deadly doctrine of nuclear deterrence by implementing a reality-based plan to get rid of nuclear weapons, a plan that involves governments, elected representatives, international organisations, civil society, the financial sector, and people and communities harmed by nuclear weapons,  including indigenous communities and women and children who are disproportionately affected by these weapons. 

This treaty is a clear solution to ending the nuclear threat as it provides a pathway under international law to fair and verifiable disarmament.  

In light of the geopolitical tensions involving nuclear-armed states, this is not the time to reduce our ambitions. Proposals such as a no-use declaration or renewal of arms control treaties will not remove the nuclear threat that the continued existence of these weapons poses.

The grave risk that nuclear weapons could be used again in conflict for the first time in 80 years means we need to keep the focus on the complete elimination of nuclear weapons and keep up the pressure on the nuclear-armed states to join the TPNW. Humanity cannot afford to let another nuclear bomb drop, or another mushroom cloud rise.