CORVALLIS, Ore. - An interdisciplinary team of researchers will explore the Earth's climatic history over the past 50,000 years by looking for signals in the geologic record that indicated the onset of rapid climate change.

Oregon State University is leading the project, which is funded by a five-year, $3.1 million grant from the National Science Foundation's Paleoclimate Program. Researchers from the University of Oregon, the University of Minnesota and the U.S. Geological Survey will join OSU scientists on the project.

The researchers will examine ocean records, ice core samples, terrestrial cave formations and global climate models looking at all aspects of climate variability, said Nicklas Pisias, a professor in OSU's College of Oceanic and Atmospheric Sciences and lead principal investigator on the study.

"A key question is whether we can detect critical points in time that signal changes in the system," Pisias said. "To do that, we need a better understanding of high-frequency climate variability - say, on the El Nino time scale - and what impact those short-term variations may have had on long-term climate, as well as better understanding of the Earth's sensitivity and response to changes in the system."

The scientists will document the range of natural variability in the Earth's systems and the rates of change within those systems. Their task is complex, Pisias says, requiring the gathering and comparing of data from multiple terrestrial and marine geologic sources using improved and novel techniques. Key periods of variability and change identified in the geologic record will be investigated by integrating that data with global and regional climate models to study the mechanisms and feedbacks that may have contributed to past climate change.

These climate models will be run on the supercomputers in the Environmental Computing Center in OSU's College of Oceanic and Atmospheric Sciences - one of the most comprehensive marine science computing systems in the world.

"Research in paleoclimatology offers the only way to document evidence of real climate impacts and is critical for understanding strategies for adaptation to changing climate," said David Verardo, director of the National Science Foundation's Paleoclimate Program. "Oregon offers unique scientific and computational talent to address this important climate question."

One innovative project, Pisias says, involves using methods developed by economists and financial analysts for predicting economic trends and adapting them to analyze past climate data sets.

These kinds of clues will be compared to other climatic markers, such as those found in mineral deposits in caves. The researchers hope that chemical analyses of these cave formations in California, Oregon, Alaska and Vancouver Island will provide other keys to regional climate history.

Other key studies will focus on sea surface temperatures, greenhouse gases, climate models and ocean circulation. Pisias said the researchers will explore whether interannual-to-centennial climate variability alters as "thresholds" to climate change approach; and whether the variability itself can actually trigger abrupt shifts in the climate.

One example, he added, is that of the North Atlantic thermohaline circulation, a mechanism that brings waters from the tropics northward, thereby moderating the climate of Europe. Scientists have shown that this ocean circulation system has been disrupted or even stopped several times in the past - and that it is sensitive to increases in temperature or fresh water that may result from global warming.

"Geologic data indicate that if it is turned off abruptly," Pisias said, "in a matter of just decades, the climate of Europe would become much cooler than present."

The research team includes OSU oceanographers Pisias and Alan Mix, the director of OSU's Stable Isotope Laboratory, who will analyze ocean records; Ed Brook, an OSU professor of geosciences, who will look at ice cores; Peter Clark, OSU geosciences, and Patrick Bartlein, UO geography, who will focus on continental records; and Steve Hostetler, USGS, and Andreas Schmittner, an OSU oceanographer, who will work on climate and ocean models. Larry Edwards, from the University of Minnesota, will work on uranium dating of cave deposits.

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Nick Pisias,