Wildfire Cloud Offers Insight on Climate Effects of Nuclear War

(CN) – Scientists studying a massive cloud that circled the Northern Hemisphere during the 2017 fire season in British Columbia, Canada, say it gives them better knowledge of nuclear war impacts on climate.

Satellite view of the wildfires in British Columbia, Canada, taken Aug. 2, 2017. (NASA)

In August 2017, extreme wildfires in western Canada pumped a continuous plume of smoke into the atmosphere that it was visible by satellite for two months. The pyrocumulonimbus cloud became the largest of its kind ever observed and scientists dubbed it the mother of all “pyroCbs.”

Sunlight heated smoke reaching the lower stratosphere, sending it aloft from 7 to 14 miles up over the two-month period. Soot absorbed the solar radiation, heating the air and fueling the smoke’s rapid rise. Because the stratosphere lacks rain to help clear it out, the smoke lingered for more than eight months.

“This process of injecting soot into the stratosphere and seeing it extend its lifetime by self-lofting was previously modeled as a consequence of nuclear winter in the case of an all-out war between the United States and Russia, in which smoke from burning cities would change the global climate,” according to co-author Alan Robock, a professor in the Department of Environmental Sciences at Rutgers University-New Brunswick.

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

Scientists used a National Center for Atmospheric Research climate model to study the lofting and movement of the enormous smoke cloud. The modeling considered smoke characteristics such as the ratio of soot to other ingredients and the rate at which ozone in the upper atmosphere broke down the smoke.

By comparison, the Canadian smoke cloud contained about 0.3 million tons of soot, while a nuclear war between India and Pakistan could produce as much as 15 million tons. A war between the United States and Russia could generate 150 million tons, according to scientists.

The rise, spread and photochemical reactions in the ozone layer provide new insights into the potential global climate impacts from nuclear war, according to Robock. He also pointed out the study of the wildfire plume helps validate his and fellow colleagues’ previous theories as well as the climate model they use for ongoing research.

The study authors will use the wildfire modeling information from this study as part of a Rutgers nuclear conflict climate modeling project. This project will refine nuclear war scenarios to determine the potential impact on the climate and food production on land and in the ocean, along with the potential for global famine, according to Robock.

The study was published Thursday in the journal Science.

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