“For a nuclear war, the global cooling would depend on the yields of the weapons, the number of weapons and the targets, among other atmospheric and geographic factors. In a nuclear war, bombs targeted on cities and industrial areas would start firestorms, injecting large amounts of soot into the upper atmosphere, which would spread globally and rapidly cool the planet.”

The reduced light and global cooling would affect agricultural produce that depends on the soil, weather, sunlight, and rain. If a nuclear war happens, these systems within the ecosystem would be disrupted, resulting in crop declines.

There’s also a factor in the wind patterns. Since nuclear explosion results in lethal chemical weapons being introduced into the air, the wind patterns from one nuclear explosion could spread smoke and fire. Food exporters in the US and China would also be affected. And since the smoke would spread in the skies, the sunlight would be affected, and various crop systems would immediately collapse. About a 90 percent drop would also happen in fishing and animal yields worldwide in just four years.

“A war between the United States, its allies, and Russia—who possess more than 90% of the global nuclear arsenal—could produce more than 150 Tg of soot and a nuclear winter. While amounts of soot injection into the stratosphere from the use of fewer nuclear weapons would have smaller global impacts, once a nuclear war starts, it may be very difficult to limit escalation.”

The research also noted that even a smaller-scale nuclear war between India and Pakistan, for example, would disrupt global food production, cut it down to 7 percent within five years, and kill 2.5 billion people. Now, with the US-Russo war, for example, the food insecurity crisis would end up killing 5 billion people on Earth.

Aside from the almost-extinction projection in the research, William Chen, a food science professor at Singapore’s Nanyang Technological University and the director of a government-affiliated food safety program, also noted the psychological impact of the damage as well. Chen added that countries should start diversifying food sources.

Ultimately, the research shows us a possible worst-case scenario.

“The data tell us one thing: We must prevent a nuclear war from ever happening,” climate scientist Alan Robock, co-author of the study, said in a statement.

The scientists don’t offer much guidance on how to prevent a nuclear war from happening, but presumably, the information on the fallout and consequences of such a war are available to both sides in such a conflict. They would understand that there are no real winners in an all-out nuclear war, and that fact in and of itself may be the best deterrent.