Studying Nuclear Winter

"The observed rapid plume rise, latitudinal spread, and photo-chemical reactions provide new insights into potential global climate impacts from nuclear war."
"The 2017 fires [British Columbia wildfires] studied here represent the first observational evidence that such a rise [self-lofting] actually occurs."
"Most nuclear winter studies have assumed that the organics in smoke can be ignored because of their rapid loss from photo-chemical reactions."
"This study calls that assumption into question given the observed persistence of the smoke in the 2017 fire plume."
Report: Rutgers University

"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 United States and Russia, in which smoke from burning cities would change the global climate."
"Even a relatively small nuclear war between India and Pakistan could cause climate change unprecedented in recorded human history and global food crises."
"The temperatures wouldn’t get below freezing in the summer like they would with a war between the United States and Russia. But it would still have devastating effects on agriculture around the world, far removed from where the bombs were dropped."
Alan Robock, distinguished professor, environmental sciences, Rutgers University/New Brunswick

A wildfire is seen from a Canadian Forces Chinook helicopter as Prime Minister Justin Trudeau views areas affected by wildfire near Williams Lake, B.C., on Monday July 31, 2017. THE CANADIAN PRESS/Darryl Dyck

There were previous events which scientists studied to arrive at a picture of how devastated the globe would be in the wake of a catastrophic event like a nuclear strike. The two U.S. strikes against Japan in 1945, when Hiroshima and Nagasaki were laid waste by atomic bombs, the most dramatic and dreadful example as one such event of unimaginable proportions; natural events like the 1991 eruption of Mount Pinatubo in the Philippines another; and the 1883 Krakatoa Indonesian eruption yet another.

It is Canada, however, with its large tracts of boreal forest and the annual wildfires that consume so much of the geography seasonally -- particularly in the ferocity of the wildfires of the last decade -- that researchers at Rutgers University studied, publishing their findings in the journal Science. The summer of 2017 and its runaway wildfires however, offered the study new insights into the potential eventuating out of nuclear war on the planet's climate.

When smoke and soot are forced upward beyond the rainy troposphere into the dry atmosphere above, the effect lingers, then boosts itself to rise further as sunlight is absorbed. That smoke and the soot accompanying it remains detectable in the upper atmosphere for months. The Pacific Northwest wildfires that began on August 12, 2017 threw up a billowing, cauliflower-shaped behemoth called a pyrocumulonimbus cloud, blotting out the sun, causing havoc with the weather system locally.

The cloud produced by the 2017 wildfires in northern British Columbia produced the largest cloud of this type ever before observed, leading the province to declare a state of emergency where thousands of people were evacuated, hundreds of fires burned out of control, and the largest land area -- about 12,000 square kilometres -- burned in a season. An immense area reduced to a dark, ruined landscape. And then, 2018 saw a repeat of the wildfires with an even larger area burned bleak and desolate.

An enormous cloud of smoke from intense wildfires drifted over northern Canada on August 15, 2017. The image is a mosaic composed from several satellite overpasses because the affected area was so large. NASA Earth Observatory

As the cloud rose from 12 kilometres in August it doubled in height two months later at which point it began to gradually fall at a rate of about one kilometre a month as it spread throughout the Northern Hemisphere stratosphere, remaining detectable even by the following April. According to expectations of nuclear winter models, once smoke reaches the upper troposphere -- the lowest atmospheric level containing water -- it becomes heated by the sun enabling it to 'self-loft' into the stratosphere where no rain is present to wash it out.

An enormous cloud of smoke from intense wildfires drifted over northern Canada on August 15, 2017. The image is a mosaic composed from several satellite overpasses because the affected area was so large.