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UA geoscientists conduct research in South American desert

By Jeff Jensen
Arizona Daily Wildcat,
January 12, 2000
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Modern models of predicting climate changes are being challenged by the work of two UA scientists.

Geoscientists Julio Betancourt and Jay Quade are conducting research in the dry South American Atacama Desert in order to more accurately predict the climatic changes of the region over the past 40,000 years.

"People have been trying to explain the coming and going of ice ages for a long time," Betancourt said. He added that this work may move scientists closer to explaining climate changes.

In a time when this desert area in northern Chile received higher amounts of precipitation, many plants and animals inhabited the region.

Among these animals were several species of rodents. These rodents produced midden - hardened urine deposits that can survive for nearly 40,000 years.

By examining this midden, Betancourt has been able to determine the types of plants that were in existence during the period in which the rodents lived.

These plants, in turn, tell a great deal about the climate. From there, the midden is radiocarbon dated in order to place the climate on a timeline.

Quade has also conducted research in this area in order to determine the height of water tables during this period.

Quade's work, combined with Betancourt's research, demonstrates that this area may not have been as dry as earlier research has stated. Their evidence, which puts high water tables between 14,000 and 9,100 years ago and 7,000 to 2,000 years ago - times that other scientists believe were dry - will hold up against earlier information gathered from lake deposits.

"When it becomes critical is when there are times in the past when changes occurred very abruptly," Betancourt said.

Future research will attempt to determine the conditions that were present during these abrupt climatic changes and whether they could occur in the present day.

This work, funded by the InterAmerican Institute, the National Geographic and the National Science Foundation, is also challenging beliefs about the importance of the tropics in determining large scale climatic changes.

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