 Have we forgotten the horrors of nuclear war? On April 22, Indian Prime Minister Narendra Modi said in a campaign speech in Rajasthan that India's nuclear arsenal was not being saved up for Diwali, implying his readiness to use them. US President Donald Trump has also casually talked about nuclear weapons on several occasions. In an interview with MSNBC, while on the campaign trail in 2016, he wondered why nuclear weapons are being made if they're not going to be used. As two important world leaders seem so cavalier about using nuclear weapons, it is important to remember the kind of damage these weapons can cause. In 1945, towards the end of World War II, two relatively small nuclear bombs were dropped by the US on Japan, causing widespread devastation. In Hiroshima, a 15-kiloton bomb killed around 140,000 people on August 6. And in Nagashaki, a 20-kiloton bomb dropped on August 9, killed around 80,000 people. The impact of the radiation continued to take lives for the next few months and left future generations afflicted with genetic disorders. The bombs also almost completely wiped out both the cities. In case a nuclear exchange did take place between India and Pakistan today, the casualties would be much greater than what we have seen in the past. If the largest known nuclear weapon tested by Pakistan, a 45-kiloton bomb was dropped on Mumbai, over 4 lakh people would be killed and over 6.5 lakh people would be injured. And if India's largest known bomb of 60-kilotons was dropped on Karachi, the death toll would be similar with 10 lakh likely to be injured. But the impact is not limited to the loss of lives. A nuclear war between two countries could spark a nuclear winter which would end the human civilization as we know it. Carl Sagan warned us about the effects of nuclear winter in a 1983 article. He pointed out that even small nuclear wars can have devastating climatic effects. A nuclear war will result in thousands of fires. The smoke from these fires alone would be enough to generate a long, cold and dark nuclear winter. The fallout from the radiation would result in huge holes in the ozone layer and the dust and soot from the fires would cover the sky and block out the sun. Temperatures would fall by several degrees. These conditions would persist across the planet for several months or even years. This nuclear winter will be enough to kill all farm animals and stop fruit production. What will be left of the human race after this is difficult to say. And the nuclear arsenal in the world today is capable of achieving this several times over. But all these existential dangers seem to be lost on the two leaders who regard nuclear bombs as mere campaign props to bolster their strongman image.