The Quelccaya Ice Cap is the largest glaciated area in the tropics. Located in the Cordillera Oriental section of the Andes mountains of Peru, the ice cap is at an average altitude of 5,470 meters (18,600 ft) and spans an area of 44 square kilometers (17 mi2). As with the majority of the Earth's glaciers, the Quelccaya Ice cap has retreated significantly since it was first studied. Since 1978 the icecap has lost approximately 20% of its area, and the rate of retreat is increasing.
Comparing pictures taken in 1963 and 1978, an annual retreat rate of 4.7 meters (15.4 ft) was estimated. In the first few years of the 21st century, the annual retreat was measured to be as much as 205 meters (672 ft), more than 40 times as fast. The major outlet glacier from the Quelccaya Ice Cap, the Quri Kalis Glacier, has also retreated significantly since 1963.