1. Massive Immediate Human Casualties
Tens to hundreds of millions could die within hours or days from direct blasts, radiation, and firestorms.
Densely populated cities like Mumbai, Karachi, Delhi, and Lahore could be entirely destroyed.
2. Regional Collapse
Medical systems would be overwhelmed or destroyed.
Infrastructure such as water, electricity, and transportation would collapse.
Mass migration and refugee crises would destabilize neighboring countries (e.g., Afghanistan, China, Iran).
3. Global Climate Effects – "Nuclear Winter"
Studies (e.g., by Alan Robock and others) estimate that even a "limited" regional nuclear war could inject 5–7 million tons of soot into the atmosphere.
This could lead to:
Global temperature drops of 1–2°C for a decade.
Major disruptions to agriculture worldwide—shortened growing seasons, lower yields.
Famine affecting up to 2 billion people, especially in food-insecure regions like Africa and parts of Asia.
4. Global Economic Collapse
Trade routes in South Asia would shut down.
Global markets would panic, leading to crashes in stock markets, commodity prices (e.g., oil, rice), and currencies.
Insurance, banking, and logistics sectors would be massively affected.
5. Political and Military Escalation
Other nuclear powers might be drawn in diplomatically or even militarily.
China, Russia, and the U.S. could be forced into high-alert situations.
Global nuclear tensions would spike—likely leading to proliferation as other countries seek deterrents.
6. Environmental Fallout
Radioactive contamination of rivers (Indus, Ganges), farmland, and air would persist for decades.
Monsoons could carry fallout to other parts of Asia.
7. Long-term Health Effects Globally
Increases in global cancer rates due to radiation exposure.
Psychological trauma worldwide—especially among diaspora communities.