January 21, 2013
Warming Soil Could Release Carbon, Enhance Effects Of Climate Change
redOrbit Staff & Wire Reports - Your Universe Online
Climate change could cause soil to grow warmer and release additional carbon dioxide into the air, enhancing the effects of global warming, a new study published in the journal Nature Climate Change has discovered.
The study, which was completed by scientists from the University of New Hampshire (UNH), the University of California-Davis (UC Davis), and the Marine Biological Laboratory (MBL), provides new insight into how microorganisms in the earth are influenced by temperature, though it also demonstrates that the phenomenon diminishes over time.
“The activities of soil microorganisms release 10 times the carbon dioxide that human activities do on a yearly basis. Historically, this release of carbon dioxide has been kept in check by plants' uptake of the gas from the atmosphere. However, human activities are potentially upsetting this balance,” officials from UNH said in a statement Sunday.
New Hampshire professor Serita Frey, Johan Six and Juhwan Lee of UC Davis and Jerry Melillo of the MBL set out to determine whether or not soils would give off different amounts of CO2 under higher-temperature conditions caused by climate change. Specifically, they wanted to know if additional heat would change the amount of carbon let off into the atmosphere in such a way as to strengthen the effects of global warming.
“The study examined the efficiency of soil organisms — how completely they utilize food sources to maintain their cellular machinery — depending upon the food source and the temperature under two different scenarios,” the university explained. In the short-term, the scientists discovered “warming temperatures had little effect on soils' ability to use glucose, a simple food source released from the roots of plants.”
“For phenol, a more complex food source common in decomposing wood or leaves, soils showed a 60 percent drop in efficiency at higher temperatures,” they added. “That effect diminishes, however, in the second scenario, in which soils were warmed to 5 degrees Celsius above the ambient temperature for 18 years.”
Essentially, Frey explains, increases in temperature lead to decreases in efficiency, leading soil-based microorganisms to release more carbon into the atmosphere, but only for more complex food sources. So it could be inferred, she added, warmer temperature caused the soil to release more CO2 into the atmosphere and theoretically intensifying the effects of climate change.
“The research team also examined how changes in soil microorganism efficiency might influence long term storage of carbon in soils as predicted by a commonly used ecosystem model,” the university said. They found “a large effect on long-term soil carbon storage as predicted by the model when they varied carbon use efficiency in a fashion comparable to what they observed in their experiments.”
“The researchers hypothesize that long-term warming may change the community of soil microorganisms so that it becomes more efficient,” UNH added. “Organism adaptation, change in the species that comprise the soils, and/or changes in the availability of various nutrients could result in this increased efficiency.”