A World of Smoke

THE OVERLOOK

By Tom Clavin

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The Northeast and Midwest have had their share this summer of smoke generated by wildfires in Canada. I agree completely that there are more – and more intense – wildfires around the world because of climate change, probably exacerbated by cutbacks in forest management. However, it was 76 years ago, well before the term climate change was coined, that North America had the granddaddy of wildfires.

The hugely destructive event burned in northern British Columbia and Alberta in the summer and early fall of 1950. With a final size of between 3,500,000 and 4,200,000 acres, it remains the single largest recorded fire in North American history. A big reason for setting the record is the authorities allowed the fire to burn freely because of the lack of settlements in the region.

The Chinchaga Fire produced large amounts of smoke, creating the so-called “Great Smoke Pall” that was observed across eastern North America and even Europe. As the existence of the massive fire was not well-publicized and the smoke was mostly in the upper atmosphere, there was much speculation about the atmospheric haze and its origin. The Chinchaga firestorm’s historic smoke pall caused observations of blue suns and moons in the United States and Europe. It was the biggest firestorm documented in North America and created the world’s largest smoke layer in the atmosphere.

Sources vary as to the origin of the fire but agree that it was caused by human activity. One version faults an Imperial Oil surveying crew with starting a small blaze to protect their horses from biting insects. Another posits that “slash burning” from agricultural clearing could have been the initial spark.

The blaze started on June 1, 1950, near the Chinchaga River and continued to burn throughout the summer and early fall until the end of October. The ignition point was north of Fort St. John, British Columbia, and the fire burned north-eastwards nearly to the Keg River in Alberta.

The path and extent of the burn was influenced by weather patterns. It burned in a fan-shaped pattern along a roughly SW/NE axis, starting in the Rose Prairie area. The fire alternated between “runs” of rapid spread and high intensity, interspersed with periods of low activity. A series of high-pressure systems over the summer allowed a buildup of heat and dry air, reducing the moisture levels in the forest fuels. The breakdowns of these systems produced the high southwesterly winds that drove the “runs.” There were five “runs” in total, with the final expansion in September causing the most destruction and amounting to one-third of the total burned area.

The Chinchaga Fire finally was put out by cooler weather and rain in late October.

Most of the burned area was on the Alberta side of the inter-provincial border, with only 220,000 acres burned on the British Columbia side. Size estimates vary due to its remoteness from population centers and the imprecise measurement techniques of the time. Estimates at the time ranged from 2,500,000 to 3,500,000 acres. In 2008 and 2009, researchers conducted airborne surveys of several boreal forest fires, including the Chinchaga. They arrived at a final estimate that was considerably larger than previous estimates, placing the total burned area at 4,200,000 acres. While most likely not the largest fire ever in North America, the burnt area it produced is the largest ever known.

No known deaths occurred as a result of the fire. In terms of damage, the dollar value of the Chinchaga Fire is difficult to estimate. Although sparsely inhabited, the area was a productive trapping area for First Nations and Metis. The timber of the Chinchaga River watershed had not been surveyed and was undervalued by the Alberta provincial government, which placed the fire’s cost at a paltry $1 million.

The Chinchaga fire produced large amounts of smoke, creating the “Great Smoke Pall” observed across eastern North America and Europe. The giant smoke release from the conflagration in late September 1950 was first recorded at Ennadai Lake, in what is now Nunavut. The smoke was on a northeastern path but hit an atmospheric trough and headed southward towards Ontario and the American eastern seaboard.

The province of Ontario experienced heavy smoke conditions that caused pitch darkness. The towns of Sarnia and Guelph experienced three-hour midday periods of darkness, streetlights in Toronto turned on by themselves, and drivers resorted to using their automobile headlights during daytime hours. In Toronto, power consumption increased by 200,000 kWh during the smoke event, causing power failures that in turn set off bank alarms, prompting police responses across the city. Aircraft were grounded, and an aerial search for a downed U.S. Air Force bomber was delayed by the smoke. Animals also felt the effects, including cows requiring milking at different times and birds were seen bedding down midday.

Most of the smoke in eastern North America was borne aloft by climatic conditions to high altitudes. As many observers could not smell it and the news of the massive Chinchaga Fire was sparse, affected people drew other conclusions about its source. Explanations included nuclear Armageddon, secret U.S. military experiments, supernatural forces, and an alien invasion.

The heavy haze moved on to the Atlantic seaboard of the United States. New York, Pennsylvania, Ohio, Washington D.C., Virginia, and Florida all reported effects from the fire, especially on September 24, which was dubbed “Black Sunday.”

American meteorologist Harry Wexler followed the smoke plume closely, collecting data from a wide area of the U.S. He noted that the plume split in two during the event, with one southern plume getting caught in a stagnant anticyclonic pattern that extended the hazy period. Wexler observed lower temperatures as result of sunlight absorption by the smoke, such as a 6-degree drop in the Washington, D.C., area.

The northern smoke plume traveled over the Atlantic by way of Newfoundland and Greenland. On September 27, the plume was observed over Scotland, with reports over England following soon after. France, the Netherlands, Portugal, and Denmark also observed the plume. Reports by pilots put the haze over Europe at 7.5 miles or more in altitude, higher than observed in North America.

In early October, a smoke observation was made on the Aleutian Islands, suggesting that the Chinchaga haze had possibly circled the entire globe.

Tom Clavin is the bestselling author/co-author of 25 books, including The First to Go West (with Bob Drury) and Vengeance, both published by St. Martin’s Press. To purchase a copy, please go to your local bookstore or to Bookshop.org, Amazon.com, BN.com, or tomclavin.com.