Nuclear war expert reveals safest part of the world to live after atomic bomb blast if WW3 broke out

A nuclear war would mean that five of the eight billion on Earth are likely to die in the first 72 minutes.

That's according to nuclear war expert and investigative journalist, Annie Jacobsen, who has opened up about what would happen if the worst were to happen.

The writer from Connecticut, US, was a 2016 Pulitzer Prize finalist after the release of her book The Pentagon's Brain: An Uncensored History of DARPA, America's Top Secret Military Research Agency.

She has since landed a role on the committee at Columbia University, and is thought to be one of the more qualified-to-speak nuclear experts around.

The 57-year-old appeared on Steven Bartlett's Diary Of A CEO podcast last year to reveal the only two countries where you might survive.

Nuclear war expert and investigative journalist Annie Jacobsen has revealed the only two countries that would survive (Getty Stock Images)

Jacobsen said that Professor Brian Toon, a leading expert on climate and atmospheric science, told her that only two countries could potentially survive a nuclear winter - New Zealand and Australia, who can 'sustain agriculture'.

She explained: "Most of the world, certainly the mid-latitudes would be covered in sheets of ice... places like Iowa and Ukraine would be just snow for 10 years.

"Agriculture would fail, and when agriculture fails people just die.

"On top of that you have the radiation poisoning because the ozone layer will be so damaged and destroyed that you couldn't be outside in the sunlight – people will be forced to live underground fighting for food everywhere except in New Zealand and Australia."

Jacobsen also believes that it would take just a window of just 72 minutes for 60 percent of humans to be wiped out.

A nuclear war would mean that five of the eight billion on Earth are likely to die in the first 72 minutes, the expert says (Getty Stock Images)

Speaking to Politico last year, she added: "It takes 26 minutes and 40 seconds for a ballistic missile to get from a launchpad in Russia to the East Coast of the United States.

"That was true in 1959-60 when [nuclear physicist and former Pentagon scientist] Herb York first had the analysis done, and it’s true today.

"Ballistic missile technology hasn’t changed the laws of gravity. No matter what you do, that still is that window to launch to your target. Pyongyang is 33 minutes because it’s a little bit different geographically."

In the event of nuclear war, the expert claims that the acting US President only has six minutes to react with the help of his 'Black Book', or 'nuclear football'.

"Part of the terrifying truth about nuclear war, or if a nuclear exchange were to unfold, is the insane time clock that was put on everything from the moment nuclear launch is detected," Jacobsen added. "This is fact.

"And so is the fact that the president has only six minutes, that’s the rough time to make this decision.

"And in that time, the Black Book gets opened; he must make a choice from a counterattack list of choices inside the Black Book."