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