Astronomers use the term albedo to define the amount of light that an object in the solar system reflects. If a planet was perfectly shiny, it would reflect 100% of the light that hit it. If a planet was perfectly dark, it would reflect 0% of the light that struck it.
Figure 1. Earth's average albedo for March 2005, measured by the Clouds and Earth's Radiant Energy Systems (CERES) instrument aboard NASA's Terra satellite.
In the albedo image above, white shows areas where Earth reflected the highest percentage of shortwave solar radiation. Dark blue shows areas where Earth reflected the lowest percentage of shortwave solar radiation. Notice how the highest albedo values are in regions where Earth is mostly covered by snow and ice, or clouds, or both. The lowest albedo values occur in forest-covered landscapes or open ocean.
If Earth was covered in ice like a giant snowball, its albedo would be about 0.84, meaning it would reflect most (84 percent) of the sunlight that hit it. On the other hand, if Earth was completely covered by a dark green forest canopy, its albedo would be about 0.14, meaning most of the sunlight would get absorbed and our world would be far warmer than it is today.
Satellite measurements made since the late 1970s estimate Earth’s average albedo to be about 0.30.
Source: http://earthobservatory.nasa.gov/IOTD/view.php?id=5484
Another estimate of the Earth's albedo results in the figure 0.367.
Source: http://www.universetoday.com/25819/albedo-of-the-earth/
Any significant changes in the brightness of the land surface or in the extent of clouds and aerosols in the atmosphere affect how much sunlight Earth reflects, which, in turn, affects the climate system. A drop of as little as 0.01 in Earth’s albedo would have a major warming influence on climate—roughly equal to the effect of doubling the amount of carbon dioxide in the atmosphere, which would cause Earth to retain an additional 3.4 watts of energy for every square meter of surface area.
Figure 1. Earth's average albedo for March 2005, measured by the Clouds and Earth's Radiant Energy Systems (CERES) instrument aboard NASA's Terra satellite.
In the albedo image above, white shows areas where Earth reflected the highest percentage of shortwave solar radiation. Dark blue shows areas where Earth reflected the lowest percentage of shortwave solar radiation. Notice how the highest albedo values are in regions where Earth is mostly covered by snow and ice, or clouds, or both. The lowest albedo values occur in forest-covered landscapes or open ocean.
If Earth was covered in ice like a giant snowball, its albedo would be about 0.84, meaning it would reflect most (84 percent) of the sunlight that hit it. On the other hand, if Earth was completely covered by a dark green forest canopy, its albedo would be about 0.14, meaning most of the sunlight would get absorbed and our world would be far warmer than it is today.
Satellite measurements made since the late 1970s estimate Earth’s average albedo to be about 0.30.
Source: http://earthobservatory.nasa.gov/IOTD/view.php?id=5484
Another estimate of the Earth's albedo results in the figure 0.367.
Source: http://www.universetoday.com/25819/albedo-of-the-earth/
Any significant changes in the brightness of the land surface or in the extent of clouds and aerosols in the atmosphere affect how much sunlight Earth reflects, which, in turn, affects the climate system. A drop of as little as 0.01 in Earth’s albedo would have a major warming influence on climate—roughly equal to the effect of doubling the amount of carbon dioxide in the atmosphere, which would cause Earth to retain an additional 3.4 watts of energy for every square meter of surface area.
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