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.

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