The UK and how it would look after a 'nuclear winter' with temperatures plunging 20C

With the exception of North Korea, before a year ago, the threat of nuclear war had been all but forgotten.

While many countries possess the weapons, the notion of using them was believed to be completely off the cards.

When Russia invaded Ukraine that question once again entered the room, and for a time an old Cold War-style standoff ensued.

Things are made more intense when North Korea is thrown into the picture, a state that regularly tests missiles, and hasn’t been afraid to shy away from openly threatening the West.

But what would such a full-scale nuclear war or regional strike look like? And how might it affect the UK?

One geostrategic expert painted a grim picture and told Express.co.uk what he thinks the world would look like in a nuclear aftermath.

North Korea missile test

Talking about an all-out nuclear war, Julian Lindley-French, Chairman of The Alphen Group (TAG) who has worked with NATO and penned numerous books on defence strategy, said: “[It] would probably lead to at least a hemispheric extinction because of a nuclear winter that may last for as long as five years, would kill crops and everything else.

“It would truly be a global war, a third World War, and would almost certainly lead to the extinction of a major part of the global population.”

Such a nuclear winter would engulf much of the world including the UK, an environmental devastation that scientists say would likely result from the explosion of not just one but hundreds of nuclear bombs during a war.

For years during the Cold War scientists were more than aware of the immediate effects of nuclear power on humans, especially after the horrific events witnessed at Hiroshima and Nagasaki, when the US dropped the world’s first atomic bombs on the two Japanese cities.

But little was studied in the way of environmental degradation and what impact this would have on humans as a result.

Dust and smoke produced from nuclear explosions would block out a significant proportion of the sun’s light and heat from the Earth’s surface.

The world would quickly become cold and dark, and estimates suggest that temperatures would drop by between 10 and 20C.

150-megaton thermonuclear explosion, Bikini Atoll, 1 March 1954.

If this were to occur during the winter, the UK could expect to experience temperatures of as low as -20C similar to those recorded in the Arctic.

Even if such an event did happen in the summer, temperatures could drop low enough to cause a chill. It would take months if not years for the sunlight to get back to its regular levels, and according to the Scientists for Global Responsibility organisation, the drop in light and temperature would “quickly kill crops and other plant and animal life.”

This would be while humans already suffering from the direct effects of the war would be vulnerable to malnutrition and disease on a “massive scale”.

In the case of an intentional or accidental nuclear exchange between the US and Russia, the bulk of the adverse effects would be felt in the northern hemisphere.

Dust and smoke would quickly circulate across the global north, yet eventually would impact the tropics, where plants and animals feel even the slightest change in temperature far more drastically than humans.

And, while the temperatures on the surface would be low, the temperature of the upper part of the troposphere – about five to 11 kilometres above – would rise because of sunlight absorbed by nuclear smoke.

World War II, after the explosion of the atom bomb.

This would result in a massively detrimental temperature inversion, trapping many pollutants at the level people breathe, creating a thick layer or dense and toxic smog.

Another little talked about effect would be the damage to the ozone layer caused by soaring levels of nitrogen oxides. Some scientists predict that as much as 70 percent of the ozone layer could be destroyed.

When the smoke eventually cleared and the sun once again shone through, there would be a spike in UV radiation penetrating the Earth’s surface, which would not only be harmful to our skin and eyes, but would destroy some of the planet’s most vital but sensitive organisms such as plankton.

It is truly a doomsday scenario, and one in which world leaders are working to avoid.

The biggest obstacle comes in the democratisation of ownership of nuclear weapons in the 21st century.

While the Cold War saw the so-called Big Powers dominate the nuclear landscape, today, unpredictable countries like North Korea, Pakistan, Iran, and even Israel all possess considerable nuclear arsenals.

“You could certainly see a situation in which a pair of regional powers go to war – Iran and Israel, India and Pakistan – and exchange nuclear weapons,” said Mr Lindley-French.

“[And] these wars could suck in bigger powers, and the biggest strike in all of this is still a major salvo exchange between those great powers.”