Quelccaya Ice Cap
Encyclopedia
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 presently 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 Qori Kalis Glacier, has also retreated significantly since 1963.
and his research team have drilled ice cores from Quelccaya that date back almost 2,000 years and have used them to study changes in atmospheric conditions over this period. In these samples, the oxygen isotope ratio
, oxygen-18
to oxygen-16, has risen abruptly in the last 50 years, an indicator of regional warming. As the ice cap is retreating, it is exposing almost perfectly preserved, unfossilized plant specimens that have been dated to 5,200 years before present, indicating that it has been more than 50 centuries since the ice cap was smaller than it is today.
Ice cores taken from Upper Fremont Glacier
in the U.S. state
of Wyoming
show an oxygen isotope profile similar to that of the Quelccaya ice cores at the end of the Little Ice Age
, a period of cooler global temperatures between the years 1550 and 1850. The sudden alterations in the oxygen isotope ratio found in ice core samples from these two glaciers, which are at great distance from each other, provide evidence of a sudden global climate change in the mid-latitude regions of the planet at this time.
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
area in the tropics. Located in the Cordillera Oriental section of the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
mountains of Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, 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 presently 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 Qori Kalis Glacier, has also retreated significantly since 1963.
Ice core study
Lonnie ThompsonLonnie Thompson
Lonnie Thompson , is an American paleoclimatologist and Distinguished University Professor in the School of Earth Sciences at The Ohio State University. He has achieved global recognition for his drilling and analysis of ice cores from mountain glaciers and ice caps in the tropical and sub-tropical...
and his research team have drilled ice cores from Quelccaya that date back almost 2,000 years and have used them to study changes in atmospheric conditions over this period. In these samples, the oxygen isotope ratio
Oxygen isotope ratio cycle
Oxygen isotope ratio cycles are cyclical variations in the ratio of the abundance of oxygen with an atomic mass of 18 to the abundance of oxygen with an atomic mass of 16 present in some substances, such as polar ice or calcite in ocean core samples. The ratio is linked to water temperature of...
, oxygen-18
Oxygen-18
Oxygen-18 is a natural, stable isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography...
to oxygen-16, has risen abruptly in the last 50 years, an indicator of regional warming. As the ice cap is retreating, it is exposing almost perfectly preserved, unfossilized plant specimens that have been dated to 5,200 years before present, indicating that it has been more than 50 centuries since the ice cap was smaller than it is today.
Ice cores taken from Upper Fremont Glacier
Upper Fremont Glacier
Upper Fremont Glacier is located in the Fitzpatrick Wilderness of Shoshone National Forest in the U.S. state of Wyoming. This Wind River Range glacier is associated with the largest grouping of glaciers in the U.S. Rocky Mountains and lies on the north slope of Fremont Peak, the third tallest...
in the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
of Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
show an oxygen isotope profile similar to that of the Quelccaya ice cores at the end of the Little Ice Age
Little Ice Age
The Little Ice Age was a period of cooling that occurred after the Medieval Warm Period . While not a true ice age, the term was introduced into the scientific literature by François E. Matthes in 1939...
, a period of cooler global temperatures between the years 1550 and 1850. The sudden alterations in the oxygen isotope ratio found in ice core samples from these two glaciers, which are at great distance from each other, provide evidence of a sudden global climate change in the mid-latitude regions of the planet at this time.