From the Ground Up
Carbon dioxide emissions from soil are on the rise
The amount of carbon dioxide being released by microbes and plants in the Earth’s soil has increased over the last two decades, according to a report in Nature.
Scientists have expected that the flow of carbon dioxide rising off the ground, also known as soil respiration, would go up along with the temperature. Evidence for this assumption, however, has been hard to come by.
Two researchers combed through 439 studies to determine whether the trend actually existed and came up with more than 1,400 measurements. They discovered that from 1989-2008, soil respiration has been increasing by 100 million metric tons of carbon per year. In temperate and tropical areas, the rise in carbon dioxide appeared to be positively linked to changes in temperature and precipitation.
It’s not yet clear whether the soils are releasing old carbon stores or responding to an increase in carbon flowing into the ground, the authors say. And surprisingly, higher temperatures in boreal and Arctic regions were linked to lower soil respiration. It’s possible that trees in boreal areas experience water stress during warm periods, the team says, which could decrease the amount of carbon entering the soil. – Roberta Kwok
Source: Bond-Lamberty, B., & A. Thomson. 2010. Temperature-associated increases in the global soil respiration record. Nature 464(7288), 579-582. DOI: 10.1038/nature08930.
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