Scientists and students, led by experts from the University of Colorado at Boulder and Rutgers University, will assess the environmental and humanitarian impact of a potential nuclear war using the most advanced scientific tools.
The study's lead authors, Professors Brian Ton and Alan Robock, have comprehensively studied the nuclear threat for decades. They were among the first to formulate the theory of "nuclear winter", according to which a nuclear war between two states can cool parts of the planet, causing mass famine even in countries not participating in the war.
In their work, published in 1983, Ton, Robock, and others drew on a 1982 study that said smoke from burning forests, cities, and oil reserves caused by nuclear explosions would block sunlight and cool the Earth. The work on "nuclear winter" was published in Science in 1983 and attracted worldwide attention.
“It surprises and saddens me that the potential catastrophic consequences of a nuclear war have ceased to be a topic of discussion that began in the 1980s,” Ton said. "One of the goals of this study is to educate people about how dangerous these weapons are by providing extensive scientific analysis of the problems."
For the first time, the new study will provide a detailed assessment of the impact of nuclear war on agriculture, the ocean food chain and people, including food availability and migratory activity. The team uses various scenarios to calculate how much smoke will be produced by city firestorms and their combustible materials.
“The most important factor is the amount of smoke from fires caused by nuclear explosions in cities and industrial areas and its spread into the upper atmosphere,” said Professor Robock. "For the first time, we will simulate fires and firestorms using detailed estimates of what will burn, based on new plausible scenarios for a nuclear war."
Although the global nuclear arsenal has been reduced by about 75% since the end of the Cold War in the 1980s, there are still about 15,000 nuclear weapons distributed among nine countries. The US and Russia have most of the weapons. Other members of the nuclear club are Britain, China, France, Israel, Pakistan, India and North Korea.
Scientists note that the threat of a nuclear incident has not diminished and it may arise due to misunderstandings, international panic, hacker attacks, terrorism, or actions by a leading nuclear power. North Korea, which has 10 to 20 nuclear weapons, continues to demonstrate its military power - most recently, the country launched an intercontinental ballistic missile, supposedly capable of reaching Alaska or Hawaii, and has been condemned by many countries, including the United States, Russia and China.
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The team uses supercomputers and sophisticated climate models developed by the National Center for Atmospheric Research (NCAR) in Boulder to calculate the amount of combustible material in major cities and the amount of smoke that can be generated from nuclear explosions. Researchers are also using agricultural and global food trade models to assess the impact of a potential nuclear war on crops and hunger.
“Calculations show that there is enough food on the planet to feed people for 60 days, while the food supply in an average city will last only 7 days,” Ton said. "The functioning of our society is largely based on our ability to transport food, fuel and other goods that will be severely affected by a nuclear war."
In 2016, Robock and Ton published a commentary in the New York Times under the headline Let's End the Peril of a Nuclear Winter. In it, they point to their 2007 study of the possible impact of a nuclear war between India and Pakistan, in which each country detonates 50 Hiroshima-sized bombs.
According to them, the smoke from the explosions will lead to a drop in temperature and, as a result, to a decrease in the production of wheat, rice, corn and soybeans globally by 10-40% within five years. Explosions can also seriously deplete the Earth's ozone layer, damaging human health and the environment.
The new project received a three-year, $ 3 million grant from the Open Philanthropy Project, a charitable organization that focuses on funding projects in four categories: US politics, global catastrophic risks, research, health and development.
As part of the Open Philanthropy work, CU Boulder Professor Yongping Hee and his students will assess the amount of flammable building materials in modern cities around the world. Professor Julia Lundqvist and her students will use sophisticated weather research and forecasting models to model how terrain and its topography might affect fire behavior after a nuclear explosion.
Robock is working with several graduate students, including Joshua Coupe, who will help with climate modeling. Another of his graduate students, Guanhu Jhong, will be working on agricultural modeling. Associate professor Gal Hohman and graduate student Hainan Zhang will focus on economic modeling.
NCAR scientists Charles Bardeen and Michael Mills use the latest atmospheric and aerosol climate models to better understand the climate system's response to soot from fires.
Based on current scientific knowledge, some of it may end up in the stratosphere (16–48 km above the earth's surface) and remain in the air for many years or even decades.
Working with Ton, Bardeen and Mills will track the emissions of gases and aerosols from urban fires, calculating their transport, removal and particle interactions with clouds, sunlight and climate.
In addition, Boulder University Assistant Professor Nicole Lovenduski and students will study how the ocean food chain might change in response to climate disruption and the increased UV radiation from nuclear explosions.
Their work will provide a clearer description of the global humanitarian impact, backed by current assessments of fires, climate change and the impact on food production, prices and constraints for a range of different possible nuclear war scenarios, the scientists said.