For the second time in two weeks, climate research by Syracuse University scientist Geoffrey Seltzer, associate professor of earth sciences in The College of Arts and Sciences, has been published in a major journal. Seltzer and a team of researchers from Duke University, East Carolina University, the University of Nebraska and SUNY Binghamton published a second article about their ongoing climate research in the Bolivian Altiplano in the Feb. 8 issue of Nature.
The Nature study, "Tropical Climate Changes at Millennial and Orbital Timescales on the Bolivian Altiplano," is related to a study published Jan. 26 in Science magazine in that it confirmed the research team's original findings that changes in climate in the Northern Hemisphere may impact climate conditions south of the equator. The Science study resulted from an analysis of sediment cores taken from Lake Titicaca, which straddles the border of Bolivia and Peru high in the Andes Mountains. The Nature study is the result of an analysis of sediment core samples the scientists obtained from the world's largest salt flat, the Salar de Uyuni, located south of Lake Titicaca on the Bolivian Altiplano at an elevation of 12,000 feet above sea level.
Both studies have produced a unique record of climate change in tropical South America that shows when global climate conditions cooled and glaciers advanced, wetter climate conditions prevailed in the Andes. When temperatures warmed up and glaciers receded, conditions in Amazonia were probably drier, Seltzer says. Evidence from the latest two studies disputes previously held beliefs that during the last glacial maximum (LGM), the climate in tropical South America was characterized by arid conditions.
The core samples from the Salar de Uyuni contained alternating layers of mud and salt that span a period of about 50,000 years. An analysis of the layers found that the salt flat was formerly occupied by a series of large and deep lakes, the latest being about 15,000 years ago, or about the same time as when the North American continent was buried under glacial ice. The lake disappeared about 10,000 years ago. "The last glacial maximum was a global phenomena, which means the entire earth cooled substantially," Seltzer says.
When lakes appeared on the Salar de Uyuni, Lake Titicaca was at its deepest and overflowed continually to the south, Seltzer says. When the level of Lake Titicaca dropped, the lakes on the Salar de Uyuni ultimately dried up.
The salt flat cores provide "a perfect correlation," says Paul Baker, the Duke University geology professor who was principal author of both journal reports.
Support for the work came from the National Science Foundation, which is also funding continuing studies on Lake Titicaca. The researchers will return to Lake Titicaca to continue drilling for deeper sediment samples on April 15. The scientists hope that the deeper samples will provide a longer record of climate change. The previous samples go back about 25,000 years.
Seltzer, Baker and Sherilyn Fritz of the University of Nebraska are the lead researchers on a team that is conducting the studies. The Salar de Uyuni team also includes Catherine Rigsby of East Carolina University and Tim Lowenstein of SUNY Binghamton.
Contact:
Judy Holmes, Syracuse University
Phone: (315) 443-3784
E-mail: jlholmes@syr.edu
Monte
Basgall, Duke University
Phone: (919) 681-8057
Email: monte.basgall@duke.edu
Tom
Simons, University of Nebraska
Phone: (402) 472-7211
