An all-out nuclear war could wipe out hundreds of millions of people around the world within the space of just a few hours.
The huge flash of blinding light when a nuclear bomb detonates is ‘like bringing a piece of the sun down to the ground’. Everything within the miles-wide firestorm is instantly incinerated.
Those spared annihilation in the initial blast would then face being poisoned to death by the radioactive fallout or noxious smog billowing from burning cities and industrial areas.
The consequences of nuclear war on the world’s climate make for even more terrifying reading. Smoke from the fires would block out the sun, reducing its warming rays by up to 70% and plunging the world into a new horror – nuclear winter.
Brian Toon, professor of atmospheric and oceanic sciences at the University of Colorado Boulder, is one of the pioneers of nuclear winter research.
He spoke to Metro about nuclear winter theory and why his warnings about it stretching back 40 years are still just as valid today.
What is nuclear winter?
Nuclear winter theory first caught the world’s attention in 1983 when one of the its most famous scientists, Carl Sagan, published an article asking ‘Would nuclear war be the end of the world?’.
In it, he wrote that ‘in a nuclear exchange more than a billion people would instantly be killed, but the long term consequences could be much worse’.
Sagan and some of his students, including Prof Toon, along with meteorologists subsequently set out in horrifying detail what those consequences would be.
They found the thick black smoke billowing from burning cities and industrial areas would rise high up into the stratosphere and block out the sun’s light.
The ensuing cold, dry and dark would send temperatures plummeting below zero and condemn billions more people to starvation with the collapse of agriculture.
The idea of mutually-assured destruction – if country A attacks country B, the retaliation by country B would render any first strike suicidal – has helped prevent nuclear war in the decades since.
But subsequent research also suggests it would be suicidal for country A to launch a first strike regardless of whether country B responds due to the climate changes caused by the smoke.
Faced with the poisoned apocalyptic world that would await any survivors of a full-scale nuclear war, former Soviet leader Nikita Khrushchev said: ‘The living will envy the dead.’
‘Like bringing a piece of the sun down to Earth’
If you live in any big city across Europe or North America it’s safe to assume there is at least one nuclear bomb aimed at you right now.
Russia has around 2,000 strategic deployed nuclear weapons. The US has roughly the same.
Between them they have around 500 cities with more than 100,000 people – that’s eight nuclear bombs for each one.
‘It only takes one of those weapons to destroy a city with 100,000 people typically,’ Prof Toon says. ‘It’s overkill.
‘If there’s a war between the US and Russia, Europe is going to be attacked, and it’s going to be attacked by nuclear weapons. It’s going to be attacked by a lot of nuclear weapons.’
He went on: ‘I recently looked at targets in Europe and I found about 650 military targets in Europe. Britain has them all over the place.’
The explosion from a nuclear bomb ‘is a lot like bringing a piece of the sun down to the ground’, Prof Toon says.
‘The bomb goes off, and there’s this huge energy release that creates an expanding fireball which is very hot. It’s initially in the millions of degrees but then soon reaches the temperature of the sun.
‘A typical nuclear weapon will destroy about a hundred square kilometres where it goes off, and most of that destruction occurs from the fires.
‘That’s what did the destruction in Hiroshima, for example, was fire. If you look at pictures of Hiroshima, there’s just rubble on the ground. A few standing concrete buildings still left.
‘And that damage was mostly from the fires.
‘In fact, for Hiroshima, the fires probably released a thousand times as much energy as the bomb itself, so they were very destructive.’
The blazes ignited by a nuclear bomb blast ‘are not normal fires’, Prof Toon says, adding: ‘It’s not just a little tiny place that is set on fire in an area – it could be 100 square kilometres – and a fire that big is going to have a smoke line that goes into the upper atmosphere.’
Mankind could go the same way as the dinosaurs
Not long before Prof Toon and his colleagues began their research it was discovered that an asteroid collision was responsible for killing the dinosaurs 66 million years ago.
There is a thin line of sediment left from the asteroid collision all over the planet.
‘That layer contains debris and rocks left from the asteroid,’ Prof Toon says. ‘Most of those look like little spheres that are about the size of a grain of sand.
‘They obviously were heated because they’re a spherical piece of rock, so we think the asteroid was vaporised when it hit the ground because of the huge energy release, which is the equivalent of a hundred million nuclear weapons going off.
‘It blew these little rock spheres all over the planet and when they re-entered the atmosphere they got hot because they were moving very fast and the friction with the air heated them up to a thousand or two thousand degrees centigrade.