One of the harshest realities of global warming is its potential to feed into itself. A recent study by researchers at the Lawrence Berkeley National Laboratory in California suggests that melting permafrost may affect the atmospheric greenhouse gas concentration.
The team studied this phenomenon in two permafrost samples from Hess Creek, Alaska, which had been frozen for 1,200 years. "Permafrost" refers to soil that has remained frozen over a large period of time — thousands or hundreds of thousands of years. The soil remains filled with the original dead plants and organisms it once contained, providing an excellent history of the sample's location. In this case, the experimenters thawed the samples over a period of days at a temperature of 41 degrees Fahrenheit to stimulate the natural melting of permafrost globally due to atmospheric warming.
The microbes within the permafrost are the danger; when the soil melts, these inhabitants begin to break it down, releasing greenhouse gases. Some of the gases contain carbon and like methane in particular, are very dangerous once they are rapidly released into the atmosphere. According to the Environmental Protection Agency, methane is "over 20 times more effective in trapping heat in the atmosphere than carbon dioxide over a 100-year period." By contributing to emissions of methane, these microbes are only furthering global warming, which increases the likelihood that more permafrost will melt. Thus, this becomes a cyclical problem.
The other main concern with the melting permafrost is its carbon content: Arctic permafrost is believed to contain approximately 250 times that of the United States' 2009 greenhouse gas emissions. As it thaws, the permafrost has the potential to emit that carbon into the atmosphere.
Through metagenomics, the study of genetic diversity without using intact organisms, the researchers were able to analyze DNA contained in the soil samples. They sequenced the DNA, and after two days and seven days observed the genetic contents and the concentrations of any emitted gases.
In respect to gas concentration, the researchers observed a swell in methane over the first two days, which then dropped significantly by the seven-day mark. The carbon dioxide concentration, however, continued to increase. The DNA evidence supports the concentration data; DNA indicating methane-producing bacteria existed throughout the experiment, but methane-eating bacteria was found to increase over the progression of days.
In the process of sequencing, the researchers found one unknown methane-producing microbe that was "fairly abundant" at two percent of the entire sequenced DNA, and they composed its draft genome, a genetic blueprint. Though very different from any previously discovered organism and still unnamed, this microbe is likely a big factor in methane production.
While it depends on environmental factors like the speed of thaw and the quantity of organic content in the soil, the methane-eating bacteria could counteract the emissions from methane-producing bacteria. However, no neutralizing force was clearly seen acting against the carbon dioxide in the experiment.
