You’ve likely heard of nuclear winter, a hypothesis explored by decades of scientific research. It’s the idea that – following the firestorms produced in an all-out nuclear war – the soot lifted into Earth’s stratosphere would cause serious cooling, and subsequent crop failures and famines. Now a new study has looked at how even a relatively contained nuclear conflict – for example, a hypothetical war between India and Pakistan – might shift the chemistry of Earth’s oceans. The reasoning is reminiscent of that behind nuclear winter: soot lifted into the atmosphere would cause cooling. In the new study, the researchers concluded that even a contained conflict would “take a toll” on the oceans and potentially disrupt the human food web.
The impacts are huge.
The journal Geophysical Research Letters published the new study in late January 2020.
These researchers used global climate models to conduct their simulations. They looked at four possible nuclear conflicts, including three in India/Pakistan of differing magnitudes (5 teragrams, 27 teragrams, and 47 teragrams of soot produced, respectively; a teragram is equal to one trillion grams or 1,000 kilotons), and one all-out U.S./Russia case with 150 teragrams of soot produced. Writing at LaboratoryEquipment.com, Michelle Taylor penned a succinct explanation of what would happen in even the “tamest” of the India-Pakistan simulations. She wrote:
… the researchers found that the conflict would likely generate huge amounts of black carbon high in Earth’s atmosphere, causing the globe to cool. Interestingly, the researchers found that the fallout from a nuclear detonation would come in two stages: the first within one year, and the second between three and five years post-bombing.
Soon after denotation and no longer than one year later, global climate models showed the acidity of the world’s oceans would likely dip. Years later, the world’s salt water would begin to suck up more carbon dioxide from the air. Supplies of carbonate in the oceans would shrink, removing the key ingredient that corals use to maintain their reefs and oysters use to sustain their shells.
Lovenduski told Taylor that – beyond taking a toll on crustaceans – a major disruption of the oceanic food web would undoubtedly severely impact the human food chain. Taylor wrote:
That’s because there are more than 3 billion people in the world today who depend on ocean fisheries for protein and/or income.
This result is one that no one expected. In fact, few people have previously considered the impact of a nuclear conflict on the ocean.
A lot of things would change in the oceans once you dim the lights [via soot in the atmosphere]. The way the water moves in the ocean, for example, is sensitive to how much heat it gets from the atmosphere …
It makes me question whether organisms could adapt to such a change. We’re already questioning whether they can adapt to the relatively slower process of man-made ocean acidification, and this would happen much more abruptly.
Lovenduski said it’s too soon to say for sure what the fate of shelled creatures in the oceans would be if nuclear war broke out. She said she hopes that her group’s findings will bring more attention to the wide-ranging devastation that would follow even a limited nuclear exchange. There’s no such thing, she said, as a minor nuclear war, adding:
I hope this study helps us to gain perspective on the fact that even a small-scale nuclear war could have global ramifications.
Bottom line: Scientists used global climate models to study various scenarios involving limited nuclear conflicts. The researchers called the impacts “huge.”
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.