Fact Check: Would Nuclear War 'Solve' Climate Change?

International nuclear tensions have become a talking point over the past couple of weeks as Vladimir Putin's war in Ukraine shows no signs of stopping.

Amid the discourse there has been mention of the global cooling effect that a small nuclear war might have.

But does the science support this controversial narrative?

Nuclear explosion
A stock illustration depicts an enormous mushroom cloud from a nuclear explosion seen from space. Scientists say even a relatively small nuclear war could have far-reaching climate effects. celafon/Getty

The Claim

On October 6, popular science and engineering Twitter account World of Engineering, which has around 2.4 million followers, tweeted that a small nuclear war would have the following effect: "Smoke from the incinerated cities rises high into the atmosphere, wrapping the planet in a blanket of soot that blocks the Sun's rays.

"Lower global temperatures 2.25 degrees Fahrenheit (1.26 degrees Celsius) for 2 to 3 years following war. In more tropical areas temperatures could fall from 5.4 to 7.2 degrees F (3 to 4 degrees C)." The thread gained over 1,000 likes.

Shortly afterwards, a video of Donald Trump Jr., son of former U.S. president Donald Trump, was posted to Twitter by former federal prosecutor Ron Filipkowski. In it, Trump Jr. is talking to camera on the topic of nuclear war and claims he read a news article last week about how "a small nuclear war … could be good for global warming or the climate crisis".

Trump Jr. did not offer specific references to the article or study that he alleges made such a claim.

Newsweek has reached out to Donald Trump Jr. and the World of Engineering account for comments.

The Facts

To unpick some of these narratives, it is worth noting first of all that the terms "global warming" and "climate change" are not interchangeable, and the former has been phased out by scientific consensus in favor of the latter, which is deemed to be more accurate and comprehensive descriptor of the seismic shifts occurring in the planet's weather and temperature patterns.

Newsweek Fact Check looked at the scientific consensus on the subject, assessing whether there is any research that would support the underlying claim.

There is ample evidence to suggest that a nuclear war would have a temporary global cooling effect (at least on land), but this is not the same as solving either global warming or the climate crisis more widely.

A study published in the journal Nature Food in August this year by researchers from multiple institutions around the world suggested that a nuclear war would eject large amounts of soot into the upper atmosphere, which would spread globally and "rapidly cool the planet."

The severity of this effect would depend on the size of the nuclear war. The study uses a hypothetical example of a nuclear war between India and Pakistan, positing that such a development could eject 5 to 47 Tg of soot into the stratosphere, while a larger hypothetical nuclear war between the U.S., its allies, and Russia could produce more than 150 Tg of soot.

Alan Robock is a distinguished professor of climate science in the Department of Environmental Sciences at Rutgers University and one of the co-authors of the study. He told Newsweek the estimate of 2.25 degrees F for 2 to 3 years put forward by World of Engineering was "wrong" and that the climate effects "depend completely on how much smoke there would be."

Regarding how long these effects would last, he added: "The length of time for the effects does not depend on the amount of smoke. For all the scenarios, there will be a five-year period of maximum effects."

Robock said the reason that a nuclear war would reduce temperatures is because the soot would rise high enough into the atmosphere that there would be no rain to wash it out. The soot would then absorb sunlight making the Earth's surface dark and cold.

Since these effects would be temporary, it is not correct to say that this would solve global warming.

Notably, whether accurate or not, the thread by World of Engineering does not suggest that the predicted drop in global temperatures would be in any way beneficial to humanity, and instead warns of dire consequences of such an event.

Indeed, when looked at in the wider context of climate change, a nuclear war would actually make things much worse by causing a whole new climate crisis.

"One factor we have not studied in depth yet is the impacts of enhanced ultraviolet (UV) light on crops, humans, and ecosystems," Robock said. "Ozone in the stratosphere would be destroyed by the heating, and that would allow more ultraviolet (UV) radiation to reach the surface. For the large stratospheric smoke loading, the smoke would absorb the excess UV for several years before its effects would be felt at the surface, but for the lowest amount of smoke, the effects would be felt immediately.

"Of course, the changed temperature, precipitation and sunlight would also affect ecosystems, and that deserves more study. It would not be good, but nobody has quantified the effects yet."

The August study by Robock and colleagues stated that the climate disruption from a nuclear war, including rapid cooling, would impact global food production systems on land and in the oceans and be "a global catastrophe for food security."

For example, severe crop declines in major exporting countries like the U.S. and Russia would trigger export restrictions and affect import-dependent countries.

These climate effects could contribute to more than 2 billion deaths globally in the case of a war between India and Pakistan and more than 5 billion deaths globally in the case of a war between the U.S. and Russia, the study states.

Other studies also point to potential indirect impacts of this type of conflict, such as immense damage to the oceans, which are likely to lead to further negative—and less predictable—consequences for the planet.

The Ruling

False

False.

While it is true that even a small nuclear war could have a global cooling effect, it is not correct to say that this would solve the climate crisis.

This is partly because the cooling effects would be temporary, and partly because a nuclear winter would be a climate crisis in and of itself, causing global food shortages and potentially billions of deaths.

FACT CHECK BY NEWSWEEK