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In May 2016 a wildfire later called 'the Beast' began southwest of Fort McMurray, Alberta, the service hub for the Athabasca oil sands. Record heat, very low humidity, strong winds and an early, dry spring drove it to about 590,000 hectares, and it was not declared extinguished until 2017.
Modern homes are built and furnished largely with petroleum-derived materials such as plastics, vinyl, foam and asphalt shingles. Once ignited they burn hotter and faster than the forest around them. Most homes are lit not by a wall of flame but by wind-blown embers landing on vulnerable surfaces, so a city behaves like a continuous fuel bed rather than a firebreak.
Burning fossil fuels warms the atmosphere, and warmer air draws more moisture out of soils and vegetation. This drying effect lengthens fire seasons and leaves fuels primed. Large fires can then generate their own weather, including pyrocumulonimbus storm clouds with lightning and erratic winds, so humans are no longer dealing with familiar wildfire but with a fire regime they have manufactured.