The threat of nuclear war no longer dominates headlines and nightmares, but that doesn’t mean the danger has receded. In fact, a new study indicates we’re probably failing to recognize how devastating it would be by focusing on only the initial damage, rather than subsequent effects on the food supply. The most frightening conclusion of the research is that even a limited exchange involving small arsenals could kill billions in non-combatant countries.
The nuclear arsenals built by the USA and the Soviet Union were so enormous both sides recognized that using them would induce “mutually assured destruction” (MAD). As the argument goes, even if one side got in first and prevented most of the other nation’s weapons from being activated, there would still be enough to cause the collapse of the initiator’s civilization.
Studies of Venus and Mars added to our knowledge of how fragile the Earth’s habitability might be, leading to the concept of “nuclear winter”, where a major exchange could plunge the world into a darkness similar to the one after the dino-killing asteroid struck.
In the 90s, however, stocks of nuclear weapons on both sides were negotiated down to the point people may have assumed a nuclear exchange would no longer be civilization-ending. Not so, according to a paper in Nature Food.
Researchers have updated the nuclear winter calculations to take account of the smaller nuclear arsenals, and the enormous advances in atmospheric modeling over the last 40 years.
They conclude that soot driven into the upper atmosphere from fires initiated by nuclear weapons would cut production of major food crops so badly deaths from starvation would far exceed those from the bomb’s direct effects. Nor should anyone think they could survive by eating a fishy diet until things got better – marine productivity would fall drastically as well.
The team modeled one scenario where conflict escalates between the US and Russia – still the holders of the most nuclear weapons despite each dismantling the bulk of their warheads. By injecting more than 150 million tonnes of soot into the atmosphere, such an event would leave every nation on Earth unable to feed its population with possible exceptions for Australia, New Zealand, and parts of South America.
The authors also considered scenarios for a war between India and Pakistan going nuclear, taking into account their more limited weapons capacity. Were the war to involve 100 nuclear weapons with an average yield of 15 kilotonnes each, the authors estimate a direct death toll of 27 million – horrendous, but around half that of World War II. However, the 5 megatonnes of soot from the fires would cut global calorie production by 7 percent and cause an estimated 255 million people to die from lack of food within the following two years. Most of the deaths would be outside the combatant nations. A larger, but still “limited” exchange could produce a death toll above two billion.
In the case of nations with larger arsenals using only a few of their weapons for battlefield purposes, as some Russian leaders implied they might do, the consequences might be similar. The whole world has an interest in ensuring peace between nuclear-armed states, although the team’s work confirms Russia’s agriculture is particularly vulnerable to small sunlight reductions.
More efficient use of food stocks – reducing waste and directly consuming cereals currently fed to cattle – might provide substantial relief in the more limited war scenarios. On the other hand, the authors note they have left possible damage to the ozone layer which could make everything even worse, to future studies.
Modeling like this always requires some assumptions – for example, in this case, that nations would respond by keeping their food production at home, rather than letting local populations go hungry to prevent wide starvation. The authors don’t, however, allow for the plausible scenario that the initial famine would spark a new set of wars over the limited remaining food stocks
“The data tell us one thing: We must prevent a nuclear war from ever happening,” Professor Alan Robock of Rutgers University said in a statement. “Banning nuclear weapons is the only long-term solution.”