Paleoecologist Cathy Whitlock researches sediment in Argentina, finding the tiny particles of pollen and ash hidden.
Cathy Whitlock is back with more layers of sediment thousands of years old to continue finding out how atmospheric changes can determine future climates in the Americas. Whitlock is a paleoecologist — part geographer, part geologist and part ecologist.
“We have to study the past to get a better idea of what’s going to happen in the future,” she said. “The climate changes projected for the next hundred years are of such a huge scale that we have to go back thousands of years to find anything comparable.”
The geography professor and department head returned in February from the second of three planned research trips to Argentina, where she and a team of scientists have unearthed deposits of sediment in lake beds and bogs.
She said the deposits, which contain particles of pollen and ash, are records of an area’s fire activity and vegetation since the Ice Age.
Whitlock said the team chose the leeward, or less windy, side of the Andes mountains in Patagonia because the climate is similar to parts of western America, with frequent rainfall in winter and relatively dry summers. Patagonia is a mountainous region occupying one-quarter of Argentina; it extends like a finger to the South Pole.
Like the North American West, destructive blazes have scorched Patagonia in the past 10 to 15 years, Whitlock said. Intense wildfires tend to burn when a period of heavy rainfall is followed by severe drought, she said.
This was the case in Yellowstone National Park in 1988 when 793,000 acres burned, according to fire history compiled by the National Park Service. But Whitlock said to find conditions comparable to those igniting wildfires in the West today, people must dig up ecological clues 6,000 to 10,000 years old.
Traditionally, most information about fire history comes from tree rings, Whitlock said. The scars caused by intense heat act as bookmarks in a forest’s fire history. But the record extends only as far back as the tree has lived, usually about 300 to 400 years.
“To get longer records of fire, we’ve been looking at charcoal particles in lake sediments,” she said. “During a fire, some of the charred needles and wood also get carried by the wind into lake bed sediments. When we find these charcoal-rich deposits, we know there was fire.”
When doing fieldwork, she also extracts and searches for pollen in sediment cores, usually samples 1 meter long and 5 centimeters thick. Plants release pollen after flowering each year, which provide handy clues to an area’s ecological history. Pollen and charcoal preserved under lake beds and bogs work best as samples. Whitlock knows where to look, but getting good samples is always a challenge.
Fellow University geography professor Pat McDowell said Whitlock is excited about the quality of the cores she brought back.
“That’s always the unknown,” McDowell said, “because you don’t know if you’ll find a lake with good sedimentation, and then you don’t know if you can get it out.”
Whitlock said the research team, funded by a grant from the National Science Foundation, is now examining the samples under microscopes. They plan to write papers and publicize the findings.
Mary Milo, who works in the University geography department, said Whitlock is visibly enthusiastic about her newest batch of samples and next phase of research, and enthusiasm that is not likely to diminish, either.
“I know it’s sort of like a dream opportunity for her to do this and get the funding.”
E-mail reporter Eric Martin
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