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Global warming is causing microorganisms that dwell in previously frozen soil to release carbon dioxide in a potentially catastrophic process that could add at least as much carbon to the atmosphere as the fossil fuel industry emitted in the mid-20th century, a study published in the journal Nature reports.

Dahr Jamail reports at Truthout:

Microorganisms in soil generally consume carbon, then release CO2 as a byproduct. Large areas of the planet — such as Alaska, northern Canada, Northern Europe and large swaths of Siberia in Russia — have previously been too cold for this process to occur. However, they are now warming up, and soil respiration is happening there. As a result, these places are contributing far, far more CO2 and methane to the atmosphere than they ever have. …

This means that even if all human fossil fuel emissions were halted immediately, soils would continue to release approximately the same amount of CO2 and methane emissions as the amount produced by the fossil fuel industry during the mid-20th century.

Soil respiration merges with the ongoing warming of the atmosphere in what scientists call a “climate feedback loop,” when separate physical processes combine to reinforce and drive each other.

The amount of CO2 that soil respiration will add to the atmosphere — on top of what humans are directly adding — is significant. “Many feedback loops are already in play, and more are coming into being on a regular basis,” Jamail writes:

The discovery of the soil feedback loop intensifies concerns about our rapidly warming climate. Increasing soil respiration — also known as “the compost bomb” — is set to add between 30 and 55 billion tons of extra CO2 to the atmosphere over the next 35 years, as Earth’s temperature warming approaches 2C.

Moreover, the study categorizes its findings as conservative estimates. In fact, the Earth could well see as much as four times the amount of CO2 (2.7 ppm) from soil respiration alone if the phenomenon becomes more wide-ranging than expected. And given that scientific predictions rarely keep pace with how rapidly the planet is changing, it would not be surprising if the prevalence exceeds expectations.

Thomas Crowther, the lead researcher on the soil study, told The Independent that the impending climate-denying Donald Trump administration could be “catastrophic for humanity.” As of 2016, humans are adding between 3.2 to 3.55 parts per million of carbon dioxide to the atmosphere. This year marks the first time CO2-increase rates have broken records two years in a row.

Global warming of two degrees Celsius “is essentially a certainty in the best-case scenario,” Jamail writes.

The Earth has already warmed by more than 1C above preindustrial baseline temperatures. It is unlikely that human civilization can survive warming of 3.5C or higher, as humans have never lived on a planet that warm. However, we are currently on track for a minimum warming of 5 to 7C, or worse, by 2100.

“It’s fair to say we have passed the point of no return on global warming, and we can’t reverse the effects,” Dr. Crowther told The Independent when the study was released. “But we can certainly dampen them.”

Other climate scientists emphasized the importance of using the soil study to inform measures to mitigate the damage of ACD. Professor Ivan Janssens with the University of Antwerp called the study “very important,” because the response of soils to ACD could well be one of the largest sources of uncertainty in climate modelling.

“We urgently need to develop a global economy driven by sustainable energy sources and start using CO2, as a substrate, instead of a waste product,” Dr. Janssens told The Independent. He suggested that if significant progress is made on this front, it may still be possible to avoid catastrophic warming.

—Posted by Alexander Reed Kelly

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