Northeastern researcher finds missing atmospheric carbon dioxide

Northeastern environmental scientist finding could improve global warming forecast models

A Northeastern University researcher today announced that he has found that the soil below oak trees exposed to elevated levels of carbon dioxide had significantly higher carbon levels than those exposed to ambient carbon levels. The findings are consistent with the hypothesis that elevated carbon dioxide levels are increasing carbon storage in terrestrial ecosystems and slowing the build-up of carbon dioxide levels in the atmosphere. Carbon dioxide is thought to cause global warming by trapping heat radiated by the Earth.

The research, published in the latest on-line edition of the journal Earth Interactions, represents an important advance in the global warming research. The lead author on the article, “Soil C Accumulation in a White Oak CO2-Enrichment Experiment via Enhanced Root Production,” is Kevin G. Harrison from the department of earth and environmental sciences at Northeastern. Contributors also include Richard J. Norby and Wilfred M. Post from the Oak Ridge National Library in Tennessee and Emily L. Chapp form the University of Hawaii.

In the study, the researchers sought to determine if the mechanism for storing carbon in soil was CO2 fertilization, the process by which plants grow better when exposed to high CO2 levels, and to investigate the extent to which CO2 fertilization could be increasing the amount of carbon stored in soil under white oak trees. The researchers studied the soil below white oak trees in the temperate zone over four growing seasons and found that the soil below trees exposed to elevated levels of CO2 had an average of 14% more carbon.

“Researchers have long been puzzled by observations that show that carbon dioxide levels in the atmosphere are increasing more slowly than expected.,” said Harrison. “This conundrum has hindered predictions of future carbon dioxide levels and, in turn, estimates of future global warming. By being able to demonstrate a substantial average increase in the carbon below these oak trees, we have potentially found the solution to better global warming forecasting. However, further research is needed in other ecosystems to see if they show similar responses to elevated carbon dioxide levels.”