An observant bird flying over Duke Forest today would notice several white rings protruding from the tree tops-but perhaps not for much longer.Unbeknownst to the bird, the suspicious rings are towers that have been emitting carbon dioxide into the canopy for more than a decade in order to simulate the effects of global warming.The experiment seeks to produce data that will improve models that predict the effects of climate change and how forests might ward off the negative consequences, said Ram Oren, professor of ecology at the Nicholas School of the Environment and the principle investigator of the experiment at Duke University.But the U.S. Department of Energy, the sole sponsor of the multi-million dollar Free Air CO2 Enrichment Project, recently requested that scientists cut to the harvesting phase by chopping down the trees and digging holes to analyze the carbon dioxide levels.The researchers object to this plan because they need at least two more years, but ideally four or five, to collect optimal results, Nicholas School Dean Bill Chameides said. Investigators at two other sites-the Oak Ridge National Laboratory in Tennessee and the Harshaw Experimental Forest in Wisconsin-also have voiced their discontent with the government's decision."Now we are at the point where we are just starting to see the change in carbon content in the soil," Chameides said.Oren pointed to the Oak Ridge site as an example of why the current phase of the project should continue for a few more years. He said the trees there showed greater productivity from the increased carbon dioxide levels up until two years ago, when they returned to normal growth rates."In order for things like that to show up, we have to allow time for the long-term processes," Oren said.The Department of Energy's reasons for the decision include wanting to publish the findings promptly and reallocating the funding to more advanced FACE projects, said Michael Kuperberg, a Department of Energy program manager in the climate and environmental sciences division."I think it's reasonable to move on," Chameides said. "But not before we finish this one. There's been a tremendous investment. Let's see it through."
As a fellow scientist, Kuperberg said he understands the researchers' eagerness to continue the current projects."There is always one more question. We want one more season, one more experiment," he said. "The very nature of science means there is another question around the corner."Results taken from the current system will prove helpful for climate change models because there are no similar experiments being conducted, Oren said. But the information cannot predict future environmental consequences as accurately as more long-term projects.Kuperberg said the Department of Energy's recommendation came from an advisory board of seven experts who are not affiliated with the government or the active projects.He rejected the perception that the department is trying to terminate funding for FACE, explaining that the funding would go toward studying the next generation of FACE systems, which will incorporate other environmental factors in addition to carbon dioxide content. These more complex systems-which include precipitation and temperature fluctuation-would more accurately predict the effects of climate change.The current economic crisis has not influenced these funding decisions, Kuperberg added. The more complex FACE systems probably will not be studied in Duke Forest, but Duke researchers are strong candidates to head the new projects, he said.