[00:11] Fire is a global agent of change that interacts with Earth's ecosystems and climate.

[00:17] In forests, periodic fires consume thick vegetation and clear the way for new growth. Seedlings thrive on the fertile soil fire leaves behind.

[00:27] Moisture and temperature largely control fire occurrence and intensity, while winds influence how fires spread.

[00:34] As Earth's climate warms, natural fire cycles are likely to be disrupted. Researchers predict global warming will lead to more intense fires that burn larger areas of land, altering the structure and function of forests.

[00:48] One way forests influence climate is by absorbing large amounts of atmospheric carbon dioxide that could otherwise warm the planet. But when trees burn, the carbon stored in them goes back to the atmosphere.

[01:01] In severe fire years, forest fires contribute as much as 40 percent of annual global greenhouse gas emissions. The frequency and severity of fires affects the balance determining whether a forest is a sink or source of greenhouse gases. Earth's temperature hangs in the balance.

[01:20] To learn more about Our Changing Planet, visit us on the web at www.umac.org/ocp.