Washington (AFP)

The worst-case scenario begins with the 2025 attack on the Indian parliament in which most of the leaders are killed. India replies by sending its tanks into the Pakistan-controlled part of Kashmir.

Fearing a total invasion, Islamabad attacks the Indian forces with small nuclear bombs called "tactics", after which the escalation is inevitable and leads to the most terrible war known to humanity, with a hundred million dead immediate and catastrophic cooling of the climate caused by the ejection into the atmosphere of black smoke columns.

These imaginary events are modeled, with scientific rigor, by researchers in a study published Wednesday in the journal Science Advances in the United States, while tensions between the two countries in Kashmir have resumed rising this summer.

India and Pakistan have about 150 nuclear warheads each in their arsenal, and are expected to have more than 200 by 2025.

"Unfortunately it is relevant because India and Pakistan are still in conflict over Kashmir, and every month people die on the border," AFP professor Alan Robock told AFP. Rutgers University in the United States, and one of the authors of the study.

The researchers estimate that up to 125 million people could be killed when using 100 kiloton bombs (six times Hiroshima). The Second World War made the order of 75 to 80 million dead.

But that would only be the beginning.

Between 16 and 36 million tons of soot would be released into the atmosphere by huge explosions and fires, say the authors.

These soot would absorb the sun's rays, heat up the air and cause smoke to rise in the upper layers of the atmosphere, reducing light reaching Earth by 20 to 35 percent.

The temperature drop at the surface would be 2 to 5 ° C, and precipitation would decrease by 15 to 30%.

The consequences would be food shortages, for years and up to a decade, for the entire planet.

"I hope people will remember from our study that nuclear weapons really should never be used, they are weapons of mass genocide," says Alan Robock.

"Two countries with a relatively small number of nuclear weapons on the other side of the world are threatening the world, we can not ignore them," he says.

© 2019 AFP