[Not another melting permafrost methane story. This time, it's CO2.
links and image in on-line article]
We Have Released a Monster: Previously Frozen Soil Is "Breathing Out"
Wednesday, December 28, 2016 By Dahr Jamail, Truthout | Report
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.
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