A study based on more than 60 years of aerial photographs has found that most glaciers in the Antarctic have been retreating because of a warmer local climate.

However, the scientists who did the study published Friday in the journal Science say it is not clear if the temperature increases were part of a natural regional cycle, or the result of human-caused "greenhouse effect."

Researchers from the British Antarctic Survey and U.S. Geological Survey analyzed about 2,000 aerial photos and satellite images. They found that 87 percent of the glaciers have retreated, by an average of 600 meters in the past 50 years. The rate of retreat was fastest in the last five years. They also found 32 glaciers that seem to be advancing rather than retreating.

Some information for this story provided by AP and AFP.