These are unsettling times we’re living in. Following a terrorist attack in Kashmir this April that resulted in the deaths of at least 26 individuals, predominantly Indian tourists, India pointed fingers at Pakistan, threatening to sever their water supply and escalated tensions further by launching airstrikes in May. In response, Pakistan warned of a “measured yet robust response,” raising fears of a broader conflict that could jeopardize global safety.

Both India and Pakistan possess roughly 170 nuclear weapons each. Should a nuclear confrontation ensue, the resultant fires in urban and industrial locales would produce vast amounts of smoke that would ascend into the stratosphere, a layer of the atmosphere above the rain-cleansing troposphere we inhabit. Our studies suggest that this smoke would obscure the sun, drastically reducing temperatures and moisture at the surface and severely impacting global agriculture for over five years, potentially leading to worldwide famine.

Unfortunately, humanity continues to face the grim prospect of nuclear conflict. However, there is an alternative path that begins with the U.S. By deactivating our land-based nuclear missiles from their high-alert status and engaging in arms reduction talks with Russia, we could pave the way for global nuclear disarmament. The U.S. could lead by example, influencing nations like Iran and others keen on developing nuclear capabilities to reconsider, by signing the Treaty on the Prohibition of Nuclear Weapons.

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The possible consequences of inaction are dire. Robock highlighted in a piece for Scientific American 15 years ago the potential for a South Asian conflict to trigger global climatic changes and jeopardize the world’s food security, though the exact magnitude of the threat was unclear at the time. Recent calculations have allowed us to predict how different nations’ agriculture might fare post-nuclear war, assuming depletion of food stores, cessation of trade, and unchanged agricultural practices. In such a scenario, a nuclear war between India and Pakistan could result in the deaths of one to two billion people from starvation within two years.

The U.S. and Russia control over 8,000 nuclear weapons combined. A nuclear clash between these superpowers could claim over six billion lives worldwide due to subsequent famine, in addition to those lost directly to blasts, radiation, and fires—as seen in Hiroshima and Nagasaki. The aftermath would be catastrophic, with 10 to 20 times more people dying from lack of food.

Many believe that nuclear war will not occur again, given the 80-year lapse since the last one. They also hold that nuclear deterrence is crucial for our safety. However, recent threats by Russia, North Korea, and even the U.S. president have stoked widespread concerns. The New START treaty, the sole remaining arms control agreement between the U.S. and Russia, is set to expire soon, while China is quickly expanding its nuclear arsenal.

President Trump recently proposed a budget that boosts the Defense Department’s funding by 13 percent, a move in the wrong direction. A significant portion of this budget is allocated for “modernizing” our nuclear arsenal, which includes land-based missiles, submarine missiles, and aircraft-droppable nuclear bombs. These weapons, which threaten near-total annihilation, should be dismantled, not updated.

The concept of deterrence is flawed. It presupposes that no party will attack because they believe we would retaliate suicidally, engulfing the world in smoke and leading to widespread starvation. This isn’t mutual assured destruction—it’s self-assured destruction.

The forthcoming Independent Study on Potential Environmental Effects of Nuclear War from the U.S. National Academies of Science, Engineering, and Medicine, the first report of its kind since 1985, is expected to underscore these risks.

The global community is acutely aware of these dangers. Following three international conferences on the humanitarian impact of nuclear weapons, the United Nations adopted the Treaty on the Prohibition of Nuclear Weapons in 2017, which came into effect in January 2021. It has been signed by 94 countries and ratified by 73, but the nine nuclear-armed nations, including the U.S., have not joined, disregarding global consensus.

The International Campaign to Abolish Nuclear Weapons (ICAN), instrumental in the treaty’s adoption, received the 2017 Nobel Peace Prize for highlighting the severe humanitarian consequences of nuclear weapons and for pioneering a treaty-based prohibition.

For deterrence to be effective, nuclear weapons must not be used accidentally by terrorists, through computer errors, hackers, or unstable leaders. History has shown we’ve come perilously close on several occasions. As Beatrice Fihn, executive director of ICAN, stated in her Nobel lecture, the choice is clear: end nuclear weapons, or they will end us.

When asked about retaining nuclear weapons for deterrence, Carl Sagan, a pioneer in nuclear-winter research, preferred a world safe from climatic catastrophes, a stance he considered basic planetary hygiene and true patriotism. We concur.

This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.