New research suggests Peru's Quelccaya Ice Cap is shrinking because of temperature, and not snowfall as has been previously suggested.
This finding supports the idea that glaciers are shrinking as a result of a warming world. Scientists expect these results to help them gain insight into the climate's "natural variability," and will help them revise climate models that work to predict future environmental patterns, a Dartmouth College news release reported.
The researchers used field mapping and a beryllium-10 surface exposure dating method to look at ice cores from the glacier. The team looked at fluctuations in the surface cover of the Quelccaya Ice Cap. The study is the first to create a "record of past glacial extents has been compared directly with an annually dated ice core record from the same ice mass."
Ohio State University paleoclimatologist Lonnie Thompson has been observing the glacier since the 1960s.
The team believes during the last millennium a "Little Ice Age" took place but researchers are unsure of what caused it and how extensive it was.
The team determined the beryllium-10 ages of glacial sediments (moraines) that mark Quelccaya's position. They found the glacier moved to its "Holocene maximum position" earlier than 520 years ago, and has been (for the most part) retreating ever since.
The moraine record and ice core record comparison temperature increases have been the "driving factor" in this retreat.
"This is an important result since there has been debate about the causes of recent tropical glacial recession - for example, whether it is due to temperature, precipitation, humidity, solar irradiance or other factors," Dartmouth glacial geomorphologist Meridith Kelly, a co-author of the study, said in the news release. "This result agrees with Professor Thompson's earlier suggestions that these tropical glaciers are shrinking very rapidly today because of a warming climate."
The "ebbs and flows" of other glaciers in South America follow the same pattern.
"On a global scale, the results suggest that glaciers were larger than present and depositing moraines in both northern and southern hemispheres at about the same time, indicating that the climate mechanisms which caused the late Holocene cooling likely influenced a globally synchronous pattern of cooling," the news release reported.
