Crop yields around the world would be slashed because nuclear weapons would trigger firestorms that release sun-blocking soot into the atmosphere, researchers found.
While this was the largest potential conflict considered, scientists also looked at what would happen in smaller nuclear wars and found billions would still die due to the obliteration of global food systems.
They looked at what would happen during five smaller India-Pakistan wars as well as a large US-Russia conflict based on the size of each country’s nuclear arsenal.
The US researchers found the smallest nuclear scenario would cause global average food production – measured in calories – to drop by 7 per cent within five years.
If a nuclear war between the US and Russia were to happen, they estimated food production would plummet by 90 per cent three to four years after any conflict.
More than 75 per cent of the world would be starving within two years under this scenario, they said.
Alan Robock, a study co-author, said the scientists understand that nuclear war of any size would obliterate global food systems and kill billions in the process.
“The data tells us one thing: we must prevent a nuclear war from ever happening,” the climate science professor from Rutgers University in New Jersey said.
Their research found crop declines would be the most severe in the mid-high latitude nations, which included Russia and the US and could have a knock-on effect on African and Middle Eastern countries that are dependent on imports.
The study has been published in the journal Nature Food.