Russia’s invasion of Ukraine brought the threat of nuclear war to the fore. But how would modern nuclear explosions affect the modern world? A new study released today sheds light on the global consequences of nuclear war.
The study’s lead author, LSU Department of Oceanography and Coastal Sciences Associate Professor Cheryl Harrison, and co-authors conducted several computer simulations to examine the effects of regional and larger nuclear war on Earth’s systems, given current nuclear war capabilities. According to the Stockholm International Peace Research Institute, nine countries currently control more than 13,000 nuclear weapons in the world.
In all of the researchers’ simulated scenarios, nuclear storms would have spewed soot and smoke into the upper atmosphere that would have blocked the Sun, leading to crop failures worldwide. In the first month after a nuclear detonation, the average global temperature will drop about 13 degrees Fahrenheit, much more than during the last ice age.
“It doesn’t matter who is bombing whom. It could be India and Pakistan, or NATO and Russia. Once smoke gets into the upper atmosphere, it spreads around the world and affects everyone,” said Harrison, who has a joint appointment at LSU’s Center for Computing and Technology.
Ocean temperatures will drop quickly and will not return to pre-war levels even after the smoke clears. As the planet gets colder, sea ice is expanding more than 6 million square miles and 6 feet deep in some basins blocking major ports, including the Beijing port of Tianjin, Copenhagen and St. Petersburg. Sea ice will spread to normally ice-free coastal regions, blocking shipping across the northern hemisphere, making it difficult to deliver food and supplies to some cities like Shanghai, where ships are not prepared to encounter sea ice.
A sudden drop in light and ocean temperatures, especially from the Arctic to the North Atlantic and North Pacific, will kill the seaweeds that form the backbone of the marine food web, essentially creating ocean starvation. This would shut down most of the fishing and aquaculture.
The researchers modeled what would happen to Earth’s systems if the United States and Russia used 4,400 100-kiloton nuclear weapons to bombard cities and industrial areas, resulting in fires releasing 150 teragrams, or more than 330 billion pounds, of smoke and absorption of sunlight. black carbon in the upper atmosphere. They also modeled what would happen if India and Pakistan detonated about 500 100-kiloton nuclear weapons, sending 5 to 47 teragrams, or 11 billion to 103 billion pounds, of smoke and soot into the upper atmosphere.
“Nuclear war leads to terrible consequences for everyone. World leaders previously used our research as a push to end the nuclear arms race in the 1980s, and five years ago to pass the United Nations Treaty on the Prohibition of Nuclear Weapons. We hope this new research will encourage more countries to ratify the ban treaty,” said co-author Alan Roebuck, professor emeritus in the Department of Environmental Sciences at Rutgers University.
This research shows the global interconnectedness of Earth’s systems, especially in the face of upheavals caused by volcanic eruptions, massive wildfires, or war.
“The current war in Ukraine with Russia and how it has affected gas prices really shows us how resilient our global economy and our supply chains are to what might appear to be regional conflict and upheaval,” Harrison said.
Volcanic eruptions also create clouds of particles in the upper atmosphere. Throughout history, these eruptions have had equally negative effects on the planet and civilization.
“We may avoid nuclear war, but volcanic eruptions will surely happen again. There’s nothing we can do about it, so when we talk about resilience and how we build our society, it’s important to consider what we need to do to prepare for the inevitable climate shocks,” Harrison said. “However, we can and must do everything possible to avoid nuclear war. The consequences are all too likely to be globally catastrophic.”
Oceans take longer to recover than land. In the largest US-Russia scenario, ocean recovery is likely to take decades at the surface and hundreds of years at depth, while Arctic sea ice changes are likely to last thousands of years and effectively become a “nuclear Little Ice Age.” The authors write that marine ecosystems will be severely disrupted both by the initial shock and in the new ocean state, leading to long-term global impacts on ecosystem services such as fisheries.