WASHINGTON (Kyodo) -- A nuclear war between the United States and Russia could put over 5 billion people in danger of starving to death due to climate disruptions caused by the use of the devastating weapons, a study published in British science journal Nature Food showed Monday.
The study highlighted the impact of massive amounts of soot that would likely be thrown into the atmosphere as a result of firestorms triggered by the dropping of nuclear bombs on cities and industrial areas. It indicated that such particles would spread through the atmosphere and result in a rapid cooling of the planet.
Soot injections totaling more than 5 million tons would lead to "mass food shortages, and livestock and aquatic food production would be unable to compensate for reduced crop output, in almost all countries," said the team that carried out the study, including Lili Xia of Rutgers university in the United States.
"In conclusion, the reduced light, global cooling and likely trade restrictions after nuclear wars would be a global catastrophe for food security," it said, noting that the research underlines "the importance of global cooperation in preventing nuclear war."
The study examined the varying impacts of six war scenarios estimated to generate up to 150 million tons of soot. A potential nuclear war between the United States and its allies against Russia was taken to be the worst case, as the countries that would be involved collectively possess more than 90 percent of the global nuclear arsenal.
Assuming some 4,400 nuclear weapons would be used in the U.S.-Russia scenario, the team said air temperatures could drop more than 14 degrees Celsius in the first few years after the war, with the cooling lasting for more than a decade.
A war between India and Pakistan, meanwhile, could produce between 5 million and 47 million tons of soot, leaving up to an estimated 2.5 billion people without food at the end of the following year.
Each scenario assumed a nuclear war lasting one week.
The global average calorie production from crops would decrease by up to 50 percent in the scenario involving 47 million tons of soot. In the case of 150 million tons, the figure could drop by around 90 percent three to four years after the nuclear war.
"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 team warned.
The study also showed that, in all six of the scenarios, the estimated number of people likely to die due to famine exceeded the potential direct fatalities of a nuclear war.
Russia's war in Ukraine, which began in February, has created fears that nuclear weapons may be used, with tensions remaining high between Moscow and the United States as it aids Kyi's self-defense efforts.
Nuclear weapons have been used twice in warfare -- the U.S. bombings of the Japanese cities of Hiroshima and Nagasaki in 1945. The number of people who had died from the bombings by the end of 1945 is estimated at 140,000 in Hiroshima and 74,000 in Nagasaki, according to the cities.