Researchers report that as the planet continues to warm, the carbon stored inside Earth’s soil could escape into the atmosphere at a much faster rate than previously expected. In a worst-case climate change scenario, carbon dioxide emissions could increase by 34 to 37 percent by 2100. In previous predictions, that number was merely nine to 12 percent, if no efforts were taken to curb climate change.
A lot of the extra carbon dioxide will come from soils at depths that had previously been overlooked in earlier studies.
Soil covers about two thirds of ice-free land on earth and store approximately three trillion metric tons of organic carbon, which is more than three times the amount of carbon that exists in the atmosphere. Dead organisms like plants can contribute to this buildup of carbon, as can microbes that eat these carbon and generate carbon dioxide that then goes into the atmosphere. The rising global temperatures will make those microbes consume plants faster, which in turn speeds up carbon dioxide creation.
How do we know this?
So what methods are scientists using to analyze the fluctuations in heat and the effects on soil environments and carbon dioxide?
Researchers have been able to mimic warming processes by heating the top five to 20 centimeters of soil in experimental areas, then measuring the CO2 emissions that result from them. These studies missed soils deeper below the surface, though, which contain more than half of the soil carbon. Warming these soils is extremely difficult, and scientists had previously assumed these emission increases far below the surface were inconsequential.
However, using heating coils and rods, a team of scientists in the Sierra Nevada region of California were able to heat the soil to a meter below ground, which was the full depth of the soil in that region. The heating was used to replicate the expected four degrees of warming that would occur by 2100 in a worst-case scenario. In this trial, annual carbon emissions rose from 1,100 grams per square meter to 1,450 grams per square meter. Around 40 percent of this increase occurred below a depth of 15 centimeters.
If other soil types behave in the same way, this means emission rates from soils deeper than 30 centimeters below the surface would equal current CO2 emission rates from all oil burning applications.
Clearly, this is yet another element of climate change scientists must test and consider in developing models for future outcomes. Heat fluctuations in soil environments over time could have a significant impact on the health of the planet moving forward. The staff at Soil Advocates would be happy to discuss any of your soil issues, contact us anytime for assistance.