October 8, 2017
Carbon Emissions From Soil Could Lead To 'Unstoppable' Global Warming

The results of an extensive study suggest that carbon emissions from warming soils are considerably higher than once thought. Scientists believe that this might trigger a chain of events that would result in a potentially unbreakable cycle of global warming.

In a study published Friday in the journal Science, researchers traced a major uptick in carbon production to the microbes found within soil. This was based on experiments conducted in the Harvard Forest in Massachusetts, as researchers heated some of the mixed hardwood forest's soil plots with underground cables, increasing temperatures by up to 40 degrees Fahrenheit (5 degrees Celsius) above normal levels. Unheated plots were used as controls for purposes of the study.

Based on the first 10 years from the time of the experiments, carbon emissions from the heated soil had increased drastically. This was followed by a seven-year period when emissions had gone down for the time being. However, this lull proved to be a proverbial calm before the storm, as the soil microbes had likely adjusted to the warmer conditions. Due to this adjustment, carbon emissions had gone back on an upward trajectory for the next six years or so.

The final three years of the study saw another decline in carbon emissions from the heated soil. The researchers believe that this might have been caused by another reorganization of the soil microbes. This points to more microbes feeding on otherwise hard-to-digest organic matter, as well as a potentially cyclical series of upticks and downticks in emissions.

As noted by The Guardian, the study spanned a total of 26 years, making it the "biggest of its kind," and a potentially "groundbreaking" way to help people understand the effects of climate change on world temperatures.

According to Daniel Metcalfe of Lund University in Sweden, the study's findings suggest that carbon emissions from soil could have a surprisingly powerful effect on the global warming phenomenon.

"If these findings hold more widely across major terrestrial ecosystems, then a much greater portion of the global soil carbon store could be vulnerable to decomposition and release of carbon dioxide under global warming than previously thought."
The Guardian wrote that feedback loops similar to what was revealed through the study have long been cited as a possible contributing factor to climate change, with increases in temperature triggering these loops and resulting in "potentially unstoppable" increases in warming. According to lead researcher Jerry Melillo of the U.S. Marine Biological Laboratory, the fluctuation in carbon emissions from warming soils is an example of such a feedback loop and a possible global issue that could be hard to stop.

"This self-reinforcing feedback is potentially a global phenomenon with soils, and once it starts it may be very difficult to turn off," Melillo told Newsweek in an interview with the publication.

"It's that part of the problem that I think is sobering."
Still, not all hope is lost, even as Melillo warned that it wouldn't be easy to curb the impact of such feedback loops. Ohio State University soil scientist Rattan Lal, who was not involved in the study, told Newsweek that management is the most important tool people can use to reduce the impact of soil-based carbon emissions on climate change. He suggested planting cover crops, mulching, and the use of nanoparticles as specific ways to protect the integrity of soil and keep it from decomposing.

Although other recent studies have hinted that global warming might not be progressing as quickly as older papers had suggested, the new study stressed that feedback loops could cause unforeseen events that are difficult to analyze in standard climate modeling. This could point to a much faster pace of global warming in the coming years. But the researchers cautioned that more studies may be needed in the future to further understand the impact of carbon emissions from warming soils.

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