This interactive activity adapted from NASA and the U.S. Geological Survey illustrates the concept of albedo—the measure of how much solar radiation is reflected from Earth’s surface. The balance between the amount of solar radiation reflected and absorbed by Earth’s surface plays an important role in regulating global temperature. Learn about how Earth materials, such as snow, ice, and water, differ in their ability to reflect and absorb the Sun’s energy and how melting polar ice creates a positive feedback loop that accelerates global warming. Investigate how the presence of pollution, such as soot, lowers the albedo of ice and further increases melting. In addition, observe the decline in Arctic sea ice cover from 1979–2007 and the effect of melting ice on sea levels.