Dude, some of us have lives to live!
https://science.howstuffworks.com/environmental/energy/energy-hurricane-volcano-earthquake2.htm
"In all, Mount St. Helens released 24 megatons of thermal energy, 7 of which was a direct result of the blast. This is equivalent to 1,600 times the size of the atomic bomb dropped on Hiroshima"
This is far more than all the nuclear weapons that Pakistan and India have.
Yes, all-out nuclear war between India and Pakistan would devastate the region in that hundreds of millions in people in Pakistan, India, BD etc would die from blast, radiation etc. It will also likely have a small scale cooling around the world that will reduce crop yields. This may increase the risk of famines in regions such as sub-Saharan Africa that do not have large stockpiles of essentials crops stockpiled.
Do not listen to the doom and gloom people who just want to get their name in the spotlight.
An all-out nuclear war between US and Russia/China would of course have the potential to make the human species extinct.