Chinchaga fire

Chinchaga River

The region has a mix of black spruce, lodgepole pine and deciduous forests, giving way to muskeg in lower areas. Few people lived in the area in 1950.[5]

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.[6] Another posits that slash burning from agricultural clearing could have been the initial spark.[5]

The blaze started on 1 June 1950 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 Keg River, Alberta.[5]

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.[7] 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 northeasterly winds that drove the "runs".[5]

There were five "runs" in total, with the final expansion in September 1950 causing the most destruction and amounting to one-third of the total burned area.[5]

It finally was put out by cooler weather and rain in late October, as it approached Keg River in the Whispering River area (hence one of its names "Whisp Fire").

Most of the burned area was on the Alberta side of the inter-provincial border, with only 90,000 hectares (220,000 acres) burned on the British Columbia side.[8] Size estimates vary due to its remoteness from population centres and the imprecise measurement techniques of the time period. Estimates at the time ranged from 1,000,000 to 1,400,000 hectares (2,500,000 to 3,500,000 acres).[5] In 2008 and 2009, researchers with Natural Resources Canada and the University of Victoria conducted airborne surveys of several boreal forest fires, including the Chinchaga. Using polarimetric analysis, they arrived at a final estimate of that was considerably larger than previous estimates, placing the total burned area at 1,700,000 hectares (4,200,000 acres).[9] While most likely not the largest fire ever in North America, maybe not even in the North American boreal forest, the burnt area it produced is the largest ever known.[5]

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 Métis. 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 one million dollars. Cordy Tymstra, an Alberta forestry department fire historian, said it is a "value that reflects how little officials appreciated the wealth of the land."[6]

Fromm et al. (2005) argued that the Chinchaga firestorm[3] may have been an iteration of an explosive troposphere-to-stratosphere transport (TST), "a dynamic combination of extreme boreal forest fire and convection [...]"[2]

The Chinchaga fire produced large amounts of smoke, creating the "1950 Great Smoke Pall", observed across eastern North America and Europe.[13] The giant smoke release from the conflagration in late September 1950 was first recorded at Ennadai Lake, in what is now Nunavut, on 24 September.[13] The smoke was on a northeastern path, but hit an atmospheric trough and headed southward towards Ontario and the American eastern seaboard.[13]

The province of Ontario experienced heavy smoke conditions that caused pitch darkness.[14] The towns of Sarnia and Guelph experienced three-hour midday periods of darkness, and city of Toronto streetlights turned on by themselves, and drivers resorted to automobile headlights during daytime hours. In Toronto, power consumption increased by 200,000 kWh during the smoke event. This caused power failures which in turn set off bank alarms – responding police cars, sirens pealing, added to the tension of the day.[15] Aircraft were grounded, and an aerial search for a downed United States military plane was delayed by the smoke. Animals also felt the effects; cows required milking at different times, and birds were seen bedding down midday.[13] Beneficially, the smoke blanket held off a killing frost that was expected in southern Ontario, saving the orchards.[15]

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, local fires, secret U.S. military experiments,[16] U.S. atomic blast,[15] supernatural forces, a solar eclipse and alien invasion.[11][13]

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, so called "Black Sunday".[17] As in Ontario, streetlights turned on during the daytime, and animals showed abnormal behaviour.[13]

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; he estimated a 4 °C (6 °F) drop in the Washington, D.C., area.[13]

The northern smoke plume traveled over the Atlantic by way of Newfoundland and Greenland. On 27 September 1950, the plume was observed over Scotland, with reports over England following soon after. France, the Netherlands, Portugal and Denmark also observed the plume.[5][6] Reports by pilots put the haze over Europe at 12 km (7.5 mi) 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.[13]

• List of fires in Canada
• List of wildfires

• Fromm, Michael; Bevilacqua, Richard; Servranckx, René; Rosen, James; Thayer, Jeffrey P.; Jay, Herman; Larko, David (27 April 2005), "Pyro-cumulonimbus injection of smoke to the stratosphere: Observations and impact of a super blowup in northwestern Canada on 3–4 August 1998", Journal of Geophysical Research: Atmospheres, 110 (D8): D08205, Bibcode:2005JGRD..110.8205F, doi:10.1029/2004JD005350
• Murphy, P.; Tymstra, C. (1986), The 1950 Chinchaga River fire in the Peace River region of British Columbia/Alberta: Preliminary results of simulating forward spread distances, Edmonton, Alberta: Canadian Forestry Services.
• Tymstra, Cordy (1 November 2014), The Chinchaga Firestorm: When the Moon and Sun Turned Blue, Edmonton, Alberta: University of Alberta Press, p. 248, ISBN 978-1772120035