The overall darkening of Mars' surface in recent decades has significantly raised the Red Planet's temperature, a possible cause for the substantial shrinkage of the planet's southern ice cap, observed in the past few years.
The brightness of an object is characterized by its albedo, the percentage of light that's reflected from its surface. Because dark objects in general absorb more solar radiation and get hotter than light ones do, albedo changes on Earth in arctic regions may be playing a part in climate change (SN: 11/12/05, p. 312: Available to subscribers at Runaway Heat?).
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