Peruvian glacial retreats linked to European events of Little Ice Age about 150 to 350 years ago

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Washington, September 25 (ANI): A new study that reports precise ages for glacial moraines in southern Peru links climate swings in the tropics to those of Europe and North America during the Little Ice Age approximately 150 to 350 years ago.

According to lead author Joe Licciardi, associate professor of Earth sciences at the University of New Hampshire, "The study brings us one step closer to understanding global-scale patterns of glacier activity and climate during the Little Ice Age.

"The more we know about our recent climate past, the better we can understand our modern and future climate," he said.

The study was borne of a convergence of a methodological breakthrough in geochronological techniques and Licciardi's chance encounter with well-preserved glacial moraines in Peru.

On vacation in 2003, Licciardi was hiking near the well-known Inca Trail when he noticed massive, well-preserved glacial moraines - ridges of dirt and rocks left behind when glaciers recede - along the way, about 25 kilometers from the ruins of Machu Picchu.

"They very clearly mark the outlines of formerly expanded valley glaciers at various distinct times in the recent past," he said.

But Licciardi, who had no geologic tools with him at the time, did not take any samples.

He returned in 2006 to the slopes of Nevado Salcantay, a 20,000-foot-plus peak that is the highest in the Cordillera Vilcabamba range.

Over the next two years, he and his graduate student Jean Taggart, also a coauthor, collected more rock samples from the moraines.

The researchers analyzed the samples using a surface exposure dating technique - measuring the tiny amounts of the chemical isotope beryllium-10 that is formed as cosmic rays bombard exposed surfaces - to place very precise dates on these relatively young glacial fluctuations.

A key finding of the study is that while glaciers in southern Peru moved at similar times as glaciers in Europe, the Peruvian record differs from the timing of glacier fluctuations in New Zealand's Southern Alps during the last millennium.

"This finding helps identify interhemispheric linkages between glacial signals around the world. It increases our understanding of what climate was like during the Little Ice Age, which will in turn help us understand climate drivers," said Taggart.

"If the current dramatic warming projections are correct, we have to face the possibility that the glaciers may soon disappear," added Schaefer.

"Our new results point to likely climate processes that can explain why these glaciers expanded and retreated when they did," said Licciardi. (ANI)

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