Over 10 crore could die in India-Pak nuclear war: Study

India and Pakistan’s nuclear forces may contain 140 to 150 warheads each in 2019 with a possible expansion of 200-250 warheads each by 2025, according to US researchers who have come out with a new study waving red flags on the threat of a nuclear war between the two arch-rivals.

More than 100 million (10 crore) people could die immediately if India and Pakistan wage a nuclear war, followed by global mass starvation, said the study published in Science Advances on Wednesday.

The study, authored by 10 researchers from seven US organisations including four universities, comes days after Pakistan Prime Minister Imran Khan warned the United Nations that his country's dispute with India over Kashmir could escalate into an all-out nuclear war that would have consequences for the world.

India has a no first use nuclear policy, but a section within the BJP-led government including the Defence Minister Rajnath Singh is in favour of an overhaul making the policy ambiguous.

The dire consequences:

In case of a nuclear war between the two neighbours in 2025, the fires ignited by exploding nuclear weapons could release 16-36 million tonnes of soot in smoke that would rise into the upper atmosphere, spreading around the world within weeks, suggests the research.

The soot or black carbon would absorb solar radiation, heating the air and boosting the smoke's swift rise.

Sunlight reaching the earth would decline by 20-35% cooling the surface by two to five degrees Celsius and reducing the rainfall by 15-30% with larger regional impacts.

"That level of warfare wouldn't just kill millions of people locally, but might also plunge the entire planet into a severe cold spell, possibly with temperatures not seen since the last Ice Age," said Brian Toon from the University of Colorado, Boulder, who led the research.

The researchers estimated the numbers of nuclear warheads on the capacity of delivery systems that can be observed from remote sensing, rather than on the amount of enriched uranium and plutonium fuel that the countries may have produced.

Using satellite images, expert studies, and local news reports, the study identified nine locations in Pakistan and five in India where nuclear weapons may be stored. They estimated that the current Pakistani weapons have yields of 5 to 12kt whereas weapons in Indian arsenal may be having a yield of 12-40kt. Much higher yields are theoretically possible.

"Such a war would threaten not only the locations where bombs might be targeted but the entire world," said Alan Robock, a distinguished professor at Rutgers University-New Brunswick and one of the authors of the study.

Unlike the rest of the world, India and Pakistan are the only two countries that are expanding its nuclear arsenal.

One of the key consequences of a nuclear war is a 15-30% decline in vegetation growth on land and 5-15% drop in ocean productivity. Recovery from all these impacts would take more than 10 years because the smoke would linger in the upper atmosphere.

"Nuclear weapons cannot be used in any rational scenario but could be used by accident or as a result of hacking, panic or deranged world leaders," Robock said. "The only way to prevent this is to eliminate them."