Until recently, scientists have been almost entirely ignoring the potential threat warmer soil has on global warming. The atmosphere holds the spotlight when it comes to the discussion of climate change, followed by the ocean and its much feared natural disasters that are triggered by global warming. Soil is a newly noticed and powerful factor that is sitting on an the edge of what could be a disastrous reaction or a possible cushion to the impact of global warming on humanity.
A recent groundbreaking study, and the longest running one of its kind, directed everyone's attention to the amount of carbon dioxide being released from soil as its temperature warms up. The study was done by splitting a patch of forest in Massachusetts, owned by Harvard, and heating specific areas to 9 F (5 C) above the usual temperature using underground cables. The study showed a release of 17% of the carbon that was stored in the top 60 cm of the soil. It also showed a cyclical nature of carbon release in which carbon released would increase then decrease over time, which scientist predict is due to microbes adjusting to the temperature change. The patch of land, rich in microbes, was divided into 6 blocks, each divided into 3 boxes. One remained untouched, one covered with heating cables and heated to 5 C above regular temperature, and one had the cables but was not heated.
The detailed analysis of the data from the experiment showed that during the first 10 years there was an increase in carbon emissions from the heated soil. This is caused by the higher rate at which microbes break down organic matter caused by higher temperatures. That was followed by a 7 year period of reduction in carbon emission, where soil microbes were able to adjust to the temperature increase. After which, carbon emissions by the soil increased again for a period of approximately 6 years.
Repeating the previous cycle the soil showed an expected reduction of carbon emission during the past 3 years due to what is thought to be a reorganization of the microbes present in the soil. The new microbes are able to digest the harder, more complex matter due to their adjustment to the heated temperatures. However, with a strong likelihood of the continuation of the previous natural cycle, scientists predict another rapid increase in carbon emissions in the next few years. The surprising discoveries of the experiment, as published recently in the journal science, sparked a fear of what could be an unstoppable spike in carbon emissions approaching soon as we near the end of the slower carbon production phase of the cycle.
Our limited understanding of organic soil activity, and the strong focus on deforestation might have been leading causes for all the additional and underprepared for soil microbial carbon dioxide emissions. What we once thought was a solution, we’ve now learned that it could be a large part of the problem. Studies of the impact of forests on climate change now need to be redirected to take into consideration new factors, such as the natural and organic cyclical activity of soil microbes.
The Soil & Global Warming
The soil beneath us carries about 3,500 billion tons of carbon, according to Jerry Melillo, a scientist at the US Marine Biological Laboratory, compared to the 10 billion tons released into the air from fossil fuel burning. Scientist estimate the global warming caused by the soil is equivalent to the warming caused by the past two decades of fossil fuel burning. The recent discoveries brought together a much needed and long overdue vision of collaboration between earth- and soil-related scientific fields of study. Due to the nature of soil, it can act as a carbon sink and hold in potential life threatening amounts of carbon dioxide. Additionally, it absorbs moisture that could otherwise be flooding land and increasing water levels. A study by Stanford showed that well managed agriculture and restoration of grasslands like US prairies can help in reducing the carbon emission from the soil.
Knowing the above, a strong increase of forces, both governmental and scientific, are directing their efforts towards implementing methods in which we can attempt to stabilize the CO2 emission from the soil. Controlling the health of forest soils and supporting the strength of agricultural communities can most assuredly benefit humanity by reducing CO2 emissions and thereby decreasing the risk of global warming. What’s more, a more soil-focused effort can mesh well with the growing abundance of farming lands for an enhanced soil capacity that keeps in unnecessary moisture and carbon from the atmosphere.