Scientists predict nuclear war climate disaster using ‘mega-cloud’ model

9 Aug 2019

Image: © Petrovich12/

Extreme wildfires in Canada in 2017 were so intense that they could tell us what ramifications the planet would experience as a result of nuclear war.

Geopolitical tensions have once again raised the topic of a potential nuclear war, leading researchers to find ways to better predict what could happen in such a disastrous situation. In a paper published to Science, researchers from Rutgers University used a recent environmental disaster as a way to create a climate model for the impacts of nuclear war.

The extreme wildfires that occurred in British Columbia, Canada, in 2017 pumped so much smoke in the upper atmosphere that the resulting cloud circled most of the planet’s northern hemisphere.

The pyrocumulonimbus (pyroCb) cloud was the largest of its kind ever observed and was quickly dubbed the ‘the mother of all pyroCbs’. When this cloud reached the lower atmosphere the sunlight heated it, rising from 11km in altitude to more than 22km.

The cloud’s key ingredient was soot that absorbed solar radiation, heating the air and fuelling the smoke’s rapid rise. With no rain to wash it out in the stratosphere, the cloud continued on for another eight months.

Satellite image in orbit of the 2017 mega cloud.

A mosaic composed from several satellite overpasses of the 2017 mega cloud because the affected area was so large. Image: NASA Earth Observatory

‘Climate change unprecedented in recorded human history’

“This process of injecting soot into the stratosphere and seeing it extend its lifetime by self-lofting was previously modelled as a consequence of nuclear winter in the case of an all-out war between the US and Russia, in which smoke from burning cities would change the global climate,” said the paper’s co-author Alan Robock.

“Even a relatively small nuclear war between India and Pakistan could cause climate change unprecedented in recorded human history and global food crises.”

Using a state-of-the art climate model from the National Center for Atmospheric Research, the researchers modelled the lofting and movement of the colossal cloud, including the ratio of soot to other ingredients and the rate at which ozone in the upper atmosphere broke down the smoke.

This showed that the smoke cloud contained about 0.3m tons of soot. By comparison, a nuclear war between India and Pakistan would produce 15m tons, while a war between the US and Russia would be 10 times that again.

The researchers said this study and the observed rapid rise of the smoke plume, its spread and photochemical reactions in the ozone layer provide new insights into the potential global climate impacts from nuclear war.

They now want to use this data to create more accurate, refined nuclear war scenarios to determine the impact on climate and food production on land and the ocean, along with the potential for global famine.

Colm Gorey was a senior journalist with Silicon Republic