A study published in the journal Nature has revealed an alarming new climate feedback loop: As Earth’s atmosphere continues to warm from anthropogenic climate disruption (ACD), soils are respirating carbon — that is, carbon is being literally baked out of the soils.
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 phenomenon is already evidenced by a recently released study led by the US National Oceanic and Atmospheric Administration (NOAA), which Truthout reported on recently.
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.
Another Tipping Point
The study showed that the uptick in soil respiration is set to add between 0.45 and 0.71 parts per million (ppm) of CO2 to the atmosphere each year between now and 2050.
Disturbingly, humans are already adding between 3.2 to 3.55 ppm of CO2 to the atmosphere as of this year, which is the first time CO2-increase rates have broken records two years in a row.
The amount of CO2 that soil respiration will add to the atmosphere — on top of what humans are directly adding — is significant.
Climate feedback loops, sometimes referred to as positive feedback loops, runaway feedback loops, or amplifying feedback loops, are important to understand if we are to truly comprehend the nature of ACD. Many feedback loops are already in play, and more are coming into being on a regular basis.
For example, when atmospheric warming caused by fossil fuel emissions leads to the melting of Arctic sea ice, the reflectivity lost by disappearing sea ice allows more solar radiation to heat the Arctic Ocean, which then causes more sea ice to melt. This is perhaps the most well-known climate feedback loop.
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.
Catastrophic for Humanity
Dr. Thomas Crowther, the lead researcher on the soil study, told The Independent that, given that ACD is happening more rapidly than expected, the impending climate-denying Trump presidency could well be “catastrophic for humanity.”
He is not exaggerating: A lot can happen in four years, when it comes to climate disruption. In fact, every year makes quite a difference. The study shows that at a minimum, 0.45ppm of CO2 will be leached from northern soils every year between 2016 and 2050, with about 1C worth of atmospheric warming during that period.
The study also shows that if Earth is warmed to 2C above preindustrial baseline temperature levels by 2050, which is essentially a certainty in the best-case scenario, then an average of approximately 0.71ppm of CO2 will be released from soils every year through the year 2050.
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.