This Is What Would Happen in a Nuclear Winter

Urban fires from the first nuclear strike would cause sooty smoke, or black carbon, arising from a city’s ruins. Though smaller in magnitude, when black carbon was injected into the atmosphere 66 million years ago – when an asteroid impact caused much of the Earth’s surface to burn – it resulted in a mass extinction event.

Wildfires ignited from a firestorm after a nuclear weapons exchange would contribute to a nuclear winter.

Smoke from fallout would block out sunlight for years, causing below-freezing temperatures.

Black carbon would absorb radiation and heat up from sunlight. As a result, the surrounding air would become buoyant, lifting soot into the stratosphere.

The buoyant aerosols would reach the higher levels of the stratosphere, encountering winds that would distribute the smoke over the Earth.