Wildfires 101 | National Geographic

Summary

Wildfires are large, uncontrolled fires that spread through natural landscapes, including forests, brush, and peatlands. In the United States, they burn an average of up to five million acres each year. Fires can start naturally, but the subtitles say that about 90% are caused by human activity.

A wildfire needs all three elements of the fire triangle:

• Heat: Sunlight, lightning, or a smoldering match.
• Fuel: Flammable material such as dry grass, leaves, trees, or living vegetation. Some evergreens contain flammable oils.
• Oxygen: Flames need oxygen to keep burning. Wind can supply more oxygen and help spread flames.

Hot, dry conditions—including those associated with warmer climates and El Niño—can make fires more likely. In the Western United States, high temperatures, drought, frequent lightning, and thunderstorms contribute to wildfire risk. Human causes include unattended campfires, improperly handled cigarettes, and arson.

Wildfires can be destructive and deadly, but they can also benefit forests by removing harmful insects and diseased plants. They can thin dense canopies, allowing sunlight to reach seedlings. Understanding the conditions that lead to fires can help people prevent and manage them, reducing harm while allowing beneficial effects.

Researchers and Sources

• Researchers: None named in the subtitles.
• Source: National Geographic. The video metadata credits some footage to NASA.