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Researchers track greenhouse gases in forests

By Sharon Omahen
University of Georgia

Monique Leclerc and Anandakumar Karipot don't just discuss global warming. They help measure the gases responsible for it. Specifically, they're building the tools to measure the flow of greenhouse gases.

This month, they're starting a three-year study in Southeastern forest canopies with a $603,000 grant from the U.S. Department of Energy.

Leclerc is a professor and Karipot an assistant research scientist with the University of Georgia College of Agricultural and Environmental Sciences. Both work in the UGA Laboratory for Environmental Physics on the CAES campus in Griffin, Ga.

Climate change and greenhouse gases

"Our lab has done a lot of research into improving methods of evaluating the amount of carbon sequestered in plant canopies," Leclerc said. "The (U.S.) Department of Energy is very interested in this type of research because climate change is such a big concern."

Greenhouse gases absorb and hold some of the heat radiating from the earth which causes the air temperature to rise. In a nutshell, that's the "greenhouse effect" involved in global warming.

Plants take in carbon dioxide, a key greenhouse gas. They use the carbon in the CO2 molecules as building blocks in their growth. Over countless years, vast amounts of plants residues form coal, oil and other fossil fuels. Burning these fuels releases CO2 back into the air.

But how much carbon does the burning release into the air? And how much do plants take out, and how fast do they do it?

How many more trees will help?

Pinpointing answers to these questions will help scientists know how many trees, crops and other plants are needed to take out the carbon all that fuel-burning is putting into the air.

Leclerc said scientists are studying many aspects of climate change worldwide. But they still don't know enough for their measurement tools to be truly accurate.

"As a nation, we need to know how much carbon is taken up by different ecosystems," she said, "and then pull this information together at a continental level."

With the DOE grant funds, Leclerc and Karipot will work with researchers at the University of California at Berkeley, University of New Hampshire, University of Florida and Brookhaven National Laboratory.

"We will release six different tracers inside the canopy and then trace their movement," she said. "Tracers are substances that can easily be traced using very sophisticated tracking devices."

Leclerc and her colleagues will be using perfluorocarbons, manmade gases, as tracers. They will release them at different levels in forest canopies and then monitor how fast they move and where.

"The concept is exactly the same in corn, sorghum or cotton field canopies," she said. "It would just be more difficult to track in these plant canopies because the instruments would have to be very, very small."

Russ Dietz, an atmospheric tracer scientist from the Brookhaven Lab in New York is one member of the team. "He is truly the best in the world in his field," Leclerc said.

Improving the current tracking model

The team's main goal is to test and improve a model for tracking gases like carbon dioxide within and above plant canopies.

"The long-term view is to mitigate climate change," Leclerc said. "We have to have a better knowledge of where gases come from in order to measure things like carbon fluxes."

Leclerc and Karipot have been studying the exchange of gases between vegetation and the atmosphere for years.

"When I was working on my master's degree in Canada, the CO2 level over the corn field was 325 parts per million," Leclerc said. "(It) would now be 355 ppm over that same field."

Americans could help reduce carbon in the air by driving smaller cars. "But no one wants to give up their SUV," she said. "Climate change is here to stay, and it's a real problem. As a scientist, I'm truly concerned."

(Dan Rahn is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)

(Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)

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