The amount of carbon stored in the world’s soils is more than double that of what is found in the atmosphere. Annually around 60bn tons of carbon is released from the soil due to microbial activity, yet there is still no consensus between researchers on whether raising temperatures would accelerate this process.
An international team of scientists led by Dr. Kristiina Karthu, a researcher from University of Helsinki, took on the task to examine closely how microbes in 22 different soils would respond to temperature change. The aim was to determine whether there is an increased risk of intensified soil carbon release as climate warms.
The overall trend showed an increase in rates of carbon release as temperatures become higher, although the responses were different depending on the initial temperature of the sample. The only soils that did not fit in this general trend were those collected from managed agricultural fields, where warmer temperatures made microbial communities release less carbon.
The most problematic are the boreal regions and the Arctic, where the rate increased significantly, making them more vulnerable than previously predicted. The situation is worsened by the fact that these soils contain half of all carbon stored in world’s soils. Although the researchers are not entirely certain to why the rates of carbon release there were so much higher as temperatures increased, they speculate that the high carbon-nitrogen ratio measured in these samples could have an impact.
The findings of the research pose serious concerns about the future. Most climate models either do not consider soil carbon at all, or significantly underestimate it, therefore any predictions made until now could actually be considered optimistic.
The study was published in latest issue of the journal Nature sets the grounds for further research, which should look more closely into the types of microbes and the impact these might have on carbon release as temperatures increase. Such work could give a huge boost to the accuracy of future prediction models, and help scientists paint a much more realistic picture.
A quick reminder, not long ago, a similar study by a team from University of New Hampshire looked into the way microorganisms respond to warmer climate, claiming that in a long term soil microorganisms will adapt and become more efficient in storing carbon.
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