Soils May Release Much Higher Levels Of Carbon Dioxide With Continued Temperature Rise Than Previously Thought

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As the world’s soils continue warming over the coming decades and centuries, they could release much higher levels of carbon dioxide than was previously thought, according to new research from the US Department of Energy’s Lawrence Berkeley National Laboratory.

The research is apparently some of the first (or the first) to investigate what happens to organic carbon present in soils at depths of 100 centimeters when all of the soil layers are warmed.

What the research found, which contradicts some assumptions, is that the annual release of carbon dioxide at the plots surged 34% to 37% when both the surface and deeper layers at 3 experimental plots used in the study were warmed. A substantial portion of the carbon dioxide released originated in the deeper layers.

Overall, what does this mean? It means that, as temperatures continue climbing, the world’s soils will release more greenhouse gases (carbon dioxide) and absorb less than was previously supposed.

Why does this matter? Because there’s roughly 3 times as much organic carbon in the world’s soils as there is in the atmosphere. To compound this, as temperatures rise, microbial and decay activity will rise in places where the conditions are right (where there’s something to decay and adequate moisture is present).

Commenting on the study findings, a researcher and co-author of the new study, Caitlin Hicks Pries, stated: “We found the response is quite significant. … If our findings are applied to soils around the globe that are similar to what we studied, meaning soils that are not frozen or saturated, our calculations suggest that by 2100 the warming of deeper soil layers could cause a release of carbon to the atmosphere at a rate that is significantly higher than today, perhaps even as high as 30% of today’s human-caused annual carbon emissions depending on the assumptions on which the estimate is based.”

So, here’s yet more evidence that those who are claiming that we can limit anthropogenic climate change associated warming to under 2° Celsius aren’t being realistic. The only way that the current and ongoing temperature rise would stay under 2° Celsius (as compared to pre-industrial temperatures) is if the world’s human population and accompanying agricultural and industrial systems were to collapse and fall off a cliff overnight.

The reality is that the inertia inherent in people’s mental processes, and even more so in the mental processes of groups of people and cultures, isn’t going to allow for any fundamental changes to occur to the current industrial and cultural systems until major repercussions start hitting in earnest … and people become even more desperate for scapegoats. Though, the window dressing and culturally approved talking points may well change before then.

The press release provides more:

“The scientists built their experiment around 6 soil plots that measure 3 meters in diameter. The perimeter of each plot was ringed with 22 heating cables that were vertically sunk more than 2 meters underground. They warmed 3 of the plots 4° Celsius for more than 2 years, leaving the other 3 plots unheated to serve as controls.

“They monitored soil respiration 3 different ways over the course of the experiment. Each plot had an automated chamber that measured the flux of carbon at the surface every half hour. In addition, one day each month, Hicks Pries and the team measured surface carbon fluxes at 7 different locations at each plot.

“A third method probed the all-important underground realm. A set of stainless steel ‘straws’ was installed below the surface at each plot. The scientists used the straws to measure CO2 concentrations once a month at 5 depths between 15 and 90 centimeters. By knowing these CO2 concentrations and other soil properties, they could model the extent to which each depth contributed to the amount of CO2 released at the surface.”

As noted towards the start of this article, what was found was that there was a 34% to 37% increase in carbon dioxide release at the warmed plots (as compared to the non-warmed ones). Roughly 40% of this increase was owing to carbon dioxide being released from below 15 centimeters.

Notably, the sensitivity of the soil in question to warming was similar across the 5 depths studied.

“There’s an assumption that carbon in the subsoil is more stable and not as responsive to warming as in the topsoil, but we’ve learned that’s not the case,” stated researcher Margaret Torn. “Deeper soil layers contain a lot of carbon, and our work indicates it’s a key missing component in our understanding of the potential feedback of soils to the planet’s climate.”

The new research is detailed in a paper published in the journal Science.

Image by Berkeley Lab

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James Ayre

James Ayre's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy.

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