The global stakes of an India-Pakistan nuclear war

 On the subcontinent, a single misstep could cast a global shadow.

Tensions between India and Pakistan are once again on the boil. A recent militant attack in Indian-administered Kashmir—one of the deadliest in recent years—has reignited hostilities between the two nuclear-armed neighbours. Political rhetoric has sharpened, security has tightened, and familiar fears of escalation are back on the global radar.

But while cross-border skirmishes and diplomatic standoffs are tragically routine, what's often forgotten is how quickly a local conflict here could snowball into a global catastrophe.

Immediate Humanitarian Catastrophe

A nuclear war between India and Pakistan could result in immediate and catastrophic loss of life. A study published in 2019 by Science Advances estimates that such a conflict could kill between 50 to 125 million people within a week, surpassing the total death toll of World War II .​

"Pakistan and India may have 400 to 500 nuclear weapons by 2025 with yields from tested 12- to 45-kt values to a few hundred kilotons. If India uses 100 strategic weapons to attack urban centres and Pakistan uses 150, fatalities could reach 50 to 125 million people, and nuclear-ignited fires could release 16 to 36 Tg of black carbon in smoke, depending on yield," the study states.

Climatic Consequences: A Nuclear Winter

Beyond the immediate devastation, a nuclear exchange would have severe climatic effects. The same study indicates that firestorms in targeted cities could inject up to 5 million tonnes of soot into the stratosphere, blocking sunlight and leading to a significant drop in global temperatures.

This phenomenon, often referred to as "nuclear winter," would disrupt monsoon patterns and reduce rainfall, particularly affecting the Indian subcontinent. The cooling and drying of the climate would have profound impacts on agriculture and water resources.

"The smoke will rise into the upper troposphere, be self-lofted into the stratosphere, and spread globally within weeks. Surface sunlight will decline by 20 to 35%, cooling the global surface by 2° to 5°C and reducing precipitation by 15 to 30%, with larger regional impacts. Recovery takes more than 10 years. Net primary productivity declines 15 to 30% on land and 5 to 15% in oceans, threatening mass starvation and additional worldwide collateral fatalities," it adds.

Global Food Security at Risk

The agricultural consequences of a nuclear conflict between India and Pakistan would be dire. A study published in Nature Food in 2022 projects that such a war could lead to a significant decrease in global food production, with maize and wheat yields dropping by up to 40% in key regions.

These reductions in crop yields would not be confined to the immediate vicinity of the conflict but would have global repercussions, potentially leading to widespread food shortages and famine. The study emphasises that the impacts on agriculture would be severe, affecting food security worldwide.​

Escalation Risks and Strategic Stability

The risk of escalation from a conventional conflict to a nuclear exchange is exacerbated by the lack of robust communication channels and confidence-building measures between India and Pakistan.

Historical analyses, including declassified US intelligence reports, have highlighted the potential for miscalculation or irrational responses to trigger a nuclear war, according to an article published by the National Security Archive on its website on 22 April 2025.

The suspension of the Indus Waters Treaty adds another layer of complexity, as water security becomes intertwined with national security concerns. Pakistan's reliance on the Indus river system for agriculture and hydropower makes any disruption a critical issue, potentially escalating tensions further