Positive Feedback Mechanisms
Positive feedback mechanisms affect the Earth's climate by enhancing the planet's environmental changes. Below are examples of positive feedback mechanisms that control temperatures on Earth.

  • A drop in Earth's temperature can cause sea ice to expand. The greater surface area of the ice results in more of the Sun's energy being reflected back into space, thus further cooling Earth's atmosphere
  • An increase in Earth's temperature can cause the amount of water vapor in the atmosphere to increase, resulting in increased cloudiness. Increased cloudiness leads to more of the Sun's energy being trapped in Earth's atmosphere, heating it further and causing ice sheets and glaciers to melt. As the ice melts, its surface area decreases, and less of the Sun's energy is reflected. Ultimately the sun's energy is absorbed by Earth, and Earth's temperature is further increased.

Image of Muir Glacier at Glacier Bay, Alaska in 1971.

Photo: Muir Glacier at Glacier Bay, Alaska in 1971. Photo courtesy of NASA's Goddard Space Flight Center.

HTML code by Chris Kreger
Maintained by ETE Team
Last updated April 28, 2005

Some images © 2004 www.clipart.com

Privacy Statement and Copyright © 1997-2004 by Wheeling Jesuit University/NASA-supported Classroom of the Future. All rights reserved.

Center for Educational Technologies, Circuit Board/Apple graphic logo, and COTF Classroom of the Future logo are registered trademarks of Wheeling Jesuit University.