A large-scale nuclear attack would have devastating effects not just on the area targeted, but on the aggressor nation as well, a new study warns.

In a first of its kind study, researchers have estimated how many nuclear weapons could put a nation past its tipping point if used – and they say it’s about 100.

Between the nine nuclear nations, however, there are roughly 15,000 nuclear weapons in the world.

Even in the best case scenario, scientists warn a major attack could trigger worldwide effects, with millions killed in the initial blast, and a global ‘nuclear autumn' leading to food shortages and mass starvation.

A large-scale nuclear attack would have devastating effects not just on the area targeted, but on the aggressor nation as well, a new study warns. File photo

The U.S. and Russia each have thousands of nuclear weapons, the researchers note, and the United Kingdom, France, China, India, Pakistan, Israel, and North Korea all have their own arsenals.

In the new study published to the journal Safety, the researchers argue the total number should be slashed to 900 or fewer - or, about 100 each.

‘With 100 nuclear weapons, you still get nuclear deterrence, but avoid the probable blowback from nuclear autumn that kills your own people,’ says Joshua Pearce, professor at Michigan Technological University.

‘Defense expenditures post-9/11 show we care about protecting Americans.

‘If we use 1,000 nuclear warheads against an enemy and no one retaliates, we will see about 50 times more Americans die than did on 9/11 due to the after-effects of our own weapons.’

The researchers examined the potential threat of three hypothetical scenarios: a 7,000-weapon arsenal, a 1,000-weapon arsenal and a 100-weapon arsenal.

They also assessed the environmental blowback, which would affect even the aggressor nation’s population.

According to the researchers, ‘No country should have more nuclear weapons than the number necessary for unacceptable levels of environmental blowback on the nuclear power’s own country if they were used.’

If just 100 weapons were fired at a densely populated city, such as one of China’s more highly inhabited areas, the blast would kill over 30 million people.

Among the nine nuclear nations, there are roughly 15,000 nuclear weapons in the world, according to the study. This includes the arsenals of U.S., Russia, the United Kingdom, France, China, India, Pakistan, Israel and North Korea. File pgoto of the Russian Navy's Bulava missile

The team modeled the burnable material to assess how much would burn in an attack, how much smoke would be produced, and how much smoke would be pumped into the atmosphere.

Soot from a large-scale nuclear attack would block out sunlight, causing temperatures and precipitation to drop.

This would trigger dramatic decreases in food production.

Even in the best case scenario, as estimated in the study, the researchers say the consequences would be grave.

HOW WOULD NUCLEAR WAR AFFECT THE ENVIRONMENT? The greatest concern over nuclear warfare derives from relatively new research which has modelled the indirect effect of nuclear detonations on the environment and climate. The most-studied scenario is a limited regional nuclear war between India and Pakistan, involving 100 Hiroshima-sized warheads (small by modern standards) detonated mostly over urban areas. Many analysts suggest that this is a plausible scenario in the event of an all-out war between the two states, whose combined arsenals amount to more than 220 nuclear warheads. In this event, an estimated 20m people could die within a week from the direct effects of the explosions, fire, and local radiation. That alone is catastrophic – more deaths than in the entire of World War I. But nuclear explosions are also extremely likely to: Nuclear explosions are extremely likely to ignite fires over a large area, which coalesce and inject large volumes of soot and debris into the stratosphere Ignite fires over a large area, which coalesce and inject large volumes of soot and debris into the stratosphere .

over a large area, which coalesce and . In the India-Pakistan scenario, up to 6.5m tonnes of s oot could be thrown up into the upper atmosphere, blocking out the sun and causing a significant drop in average surface temperature and precipitation across the globe, with effects that could last for more than a decade.

and precipitation across the globe, with effects that could last for more than a decade. This ecological disruption would, in turn, badly affect global food production. According to one study, maize production in the US (the world's largest producer) would decline by an average by 12% over ten years in our given scenario.

According to one study, maize production in the US (the world's largest producer) would decline by an average by 12% over ten years in our given scenario. In China, middle season rice would fall by 17% over a decade, maize by 16%, and winter wheat by 31%. With total world grain reserves amounting to less than 100 days of global consumption, such effects would place an estimated 2 billion people at risk of famine. Advertisement

‘We should be clear this analysis represents a severe underestimate on the number of dead Americans,’ Pearce says.

‘We assume severe rationing, which is the best way to keep the most people alive when there is this level of food shortage.

‘It means anyone who would die of starvation is immediately cut off from food. I don’t think rationing would go overly smoothly – a lot more people would die in violence internally than what we estimated based on lack of calories.’

The researchers used climate and crop simulation, coupled with the smoke models, to assess the impacts on food supply if 100 nuclear weapons were used.

And, they say there could be 10-20 percent agricultural loss due to the so-called nuclear autumn

This could lead to food shortages in wealthier nations, and mass starvation in poorer countries.

Based on the findings, the researchers argue that maintaining more than 100 nuclear weapons is against a nation’s best interest.