Pearls and Irritations

An important new study published in Nature Food on 15 August by Lili Xia and Alan Robock of Rutgers University together with colleagues around the globe shows just how dangerous even a “limited” nuclear war in one part of the world would be.

Even a nuclear war in which less than 3% of the world’s 12,705 nuclear weapons were exploded would decimate crop production and result in widespread starvation. For the first time, the study provides detailed estimates of impacts from various feasible scenarios for nuclear war on major food sources in every country.

The study used a 2010 population dataset for a global population that was then 6.703 billion. Today, world population is close to 8 billion. So bear in mind that all the study’s estimates of numbers of people affected are lower than if nuclear war happened today with 19% more people on our planet.

The findings are stark and confronting. Except for some imminent cataclysmic cosmic event which we have no power to stop bearing down on us, its hard to think of any scientific evidence of greater moment for the future of humankind and the biosphere.

“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 researchers explain. The cooling even for a “limited” nuclear war in one region would abruptly plummet global temperatures to those last seen during the coldest period of the last ice age 20,000 years ago. The resultant cooling, drying and darkening persist for over a decade.

The UN Food and Agriculture Organisation (FAO) estimates that in 2021, up to 828 million people were undernourished, 150 million more than 2 years earlier before the COVID-19 pandemic. FAO also assess that 2.3 billion people were moderately or severely food insecure in 2021, 350 million more than pre-COVID. Global grain reserves usually hold 3 – 4 months worth of consumption. We are not well positioned to endure large declines in food production over multiple years.

Xia and colleagues examine the effects of the climate disruption on major crops, and take into account all or some livestock being killed for food, crops that normally feed livestock being eaten by people instead, differing degrees of reduction in current levels of household food waste (20% globally), whether trade in food continues or more likely based on historic experience stops, and how equitably food is distributed (with the current high level of inequity expected to worsen).

There are many factors the researchers don’t take into account that would make the situation worse. They don’t include deaths from the immediate blast, burns and radiation. They do not model the effect of the dramatic increase in ultraviolet radiation that would follow the ozone depletion in a smoky upper atmosphere heated by the smoke. This UV increase would be toxic to plant and animal growth and development both on land and in the water.

They do not model the profound effects likely on availability of fuel, fertiliser, seed, pesticides, farm machinery supply and parts, food storage and transport infrastructure from the profound worldwide social, economic and trade disruption that would follow a nuclear war.

They do not model the land needing to be taken out of production and produce needing to be discarded because of radioactive fallout and chemical contamination from damaged, burning and leaking chemical and industrial facilities and storage sites.

They also don’t model what adaptations to farm management, cultivar selection and alternative food sources might be able to be made quickly.

Overall, the estimates Xia and colleagues provide are very likely to be a conservative baseline.

Their conclusion:

“The reduced light, global cooling, and likely trade restrictions after nuclear wars would be a global catastrophe for food security. The negative impact of climate perturbations on the total crop production can generally not be offset by livestock and aquatic food. More than 2 billion people could die from a nuclear war between India and Pakistan, and more than 5 billion could die for a war between the U.S. and Russia. The results here provide further support to the 1985 statement by U.S. President Ronald Reagan and Soviet General Secretary Mikhail Gorbachev, and restated by Presidents Biden and Putin in 2021, that “a nuclear war cannot be won and must never be fought.”

Diving into the science of years without summer

Building on past research, Xia, Robock and colleagues calculated how much Sun-blocking soot would enter the atmosphere from firestorms ignited by the detonation of nuclear weapons of various likely sizes on cities. The researchers calculated soot dispersal from six scenarios – five smaller India-Pakistan wars and a large US-Russia war – based on the size of each country’s nuclear arsenal and how a nuclear war would be most likely to unfold (Table).

Its important to say that there’s nothing specific to a nuclear war between India and Pakistan in disrupting the global climate and food production. Sooty smoke from burning cities and industrial facilities ignited by nuclear weapons anywhere in the world would have similar effects as the soot rises and spreads in the same sky.

These data were entered into the Community Earth System Model, a climate forecasting tool supported by the US National Center for Atmospheric Research (NCAR). The NCAR Community Land Model made it possible to estimate productivity of major crops (maize, rice, spring wheat and soybean) on a country-by-country basis under the perturbed climate. The researchers also examined projected changes to livestock pasture and global marine fisheries.

Under even the smallest nuclear scenario, a localised war between India and Pakistan, global average caloric production decreased 7 percent within 5 years. In the largest war scenario studied – a full-scale US-Russia nuclear conflict – global average caloric production decreased by about 90 percent 3 to 4 years after the war.

These changes would induce a catastrophic disruption of global food markets. Even a 7 percent global decline in crop yield would exceed the largest anomaly ever recorded since the beginning of FAO observational records in 1961. Under the largest war scenario, more than 75 percent of people on the planet would be starving within two years.

The researchers evaluated whether humans eating crops normally fed to livestock or reducing food waste could offset caloric losses in a war’s immediate aftermath, but the savings were minimal.

A nuclear war of any size would obliterate global food systems, killing billions of people in the process.

The effect of where you live

This study for the first time provides detailed estimates of declines in crop production and deaths from starvation for every country. Crop declines are not evenly distributed – already cool to cold countries at high latitudes would be worst affected. Many of these – such as Russia, China, Ukraine and the US are the world’s largest food exporters, also making highly import-dependent countries in Africa, the Middle East and Asia vulnerable to severe declines in available food.

For the ‘middle’ India-Pakistan scenario of 250 nuclear explosions of 50 kt each, generating 27 million tons of soot (Table), the declines in major food crops in selected countries in year 2 after nuclear war are as follows: Canada 96%, China 64%, North Korea 91%, Russia 84%, Ukraine 26%, US 67%. The declines after Russia-US nuclear war for each of these countries are over 99%. Australian agriculture fares relatively well in all scenarios (with 7% decline for the 27 million ton scenario and 24% for the Russia-US war). However as the authors note: ” Australia and New Zealand would likely see an influx of refugees from Asia and other countries experiencing food insecurity.”

Right now in New York

As co-author Professor Alan Robock concludes: “The data tell us one thing: We must prevent a nuclear war from ever happening.”

The government representatives from almost all nations meeting right now in New York for the Review Conference of the nuclear Non-Proliferation Treaty, including Australia, should draw the clear implications of this evidence and act on them with urgency. Nuclear-armed nations which legally committed to eliminate their nuclear arsenals 52 years ago are again demanding that other nations renew and strengthen their pledge not to acquire nuclear weapons, while they will not even commit not to use their nuclear weapons first or to blow up the world with the weapons they not only steadfastly refuse to eliminate, but are making more destructive, accurate, flexible and “usable”. We are in the existential race of our lives to end these global suicide bombs before they end us.

Table: Scenarios for nuclear war between India-Pakistan and Russia-US and numbers of people worldwide without food 2 years later. Adapted from Xia L et al, Nature Food, August 2022.

The nuclear weapon which destroyed and burnt Hiroshima was equivalent to 15,000 tons of high explosive (15 kilotons – kt). The average size of nuclear weapons in the global arsenal is 160 kt. The largest nuclear weapons currently deployed are up to 5000 kt in size. India currently holds 160 nuclear weapons and Pakistan 165 – both arsenals are growing. Russia has 4477 nuclear weapons and the US 3708 in their military stockpiles.

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