My last post
acknowledged the dramatic shift in Gaia's order caused by the advent
of the Anthropocene, the newly-named geological period in which Homo
sapiens has become what Brian Swimme calls a “planetary power.” I
began this series of posts by examining some of the proposals for
geo-engineering in the face of momentous climate change, particularly
emphasizing the advantages of limiting incoming solar radiation,
versus the much costlier methods of carbon capture and storage (CCS).
I received responses
from two people I highly respect, each of them questioning my
analysis. The first pointed out that I had overlooked the potential
of carbon sequestration in soils, something I was aware of, but
indeed overlooked in my emphasis on the high-tech quality of
anthropocentric mediation of a typically anthropocene problem. The
gentleman linked me with the Rodale Institute's study, “Regenerative Organic Agriculture and Climate Change”
, which I had seen but
I will return to
that study, but lay out the topic with the aid of a
characteristically comprehensive review of the subject by Judith
Schwartz, “Soil as Carbon Storehouse: New Weapon in Climate Fight?”, in Yale's Environment 360
. Schwartz summarizes many
key studies, stating at the outset that 50-70% of the world's
original soil carbon stock has been lost, almost all oxidized as CO2.
The essential job is to restore this carbon by recovering degraded
lands, primarily long-grass prairies, but also wetlands and of course
forests. The most promising sites for restoration include the former
NA prairie, the North China Plain, and the parched interior of
Australia. This would be a triple-win, sequestering CO2, boosting
soil productivity (restoring dirt to actual soil), and increasing
resilience to floods and drought.
The methods by which
this could be achieved include cover cropping, no-till or minimal
till (strip-till) agriculture, and agro-forestry, where croplands,
trees, and ruminant animals would be integrated into one interrelated
system. Some of the key principles wold be mulching rather than
burning, largescale use of biochar, and restoration of mangroves,
salt marshes, and sea grasses.
liberally from an interview with biogeochemist Thomas Goreau, who
makes the key point that current efforts to slow the climate change
train are focused on CO2 sources, whereas
we need to look equally at its destination
– where CO2 can and should go. Goreau says that degraded,
deforested land could create biochar for housing soil carbon by using
the on-site weeds for pyrolysis.
important vehicle for moving carbon into soil is root
- mycorrhizal – fungi.
Discovered only in 1996,
recent research shows that
these fruiting, mushroom-like bodies can enable soils they inhabit to
absorb 70% more carbon per unit of nitrogen. This confirms the theory
of Rudolf Steiner, father of biodynamic gardening, a century ago.
Now what seemed quasi-mystical has a firm “scientific” basis.
That is, Goethean/Anthroposophic science now has confirmation from
the more reductive type.
has recently published a book, Cows Save the Planet and Other Improbable Ways of Restoring Soil to Heal the Earth,
in which she argues for Holistic
Planned Grazing, pioneered in Argentina and Zimbabwe, where livestock
grazing is patterned after wild ruminants' co-evolved grazing pattern
with traditional grasslands. Animals are moved to prevent
overgrazing, and in the process not only is their manure evenly
spread, but their trampling aerates the soil, pushing seeds in as
well as dead plant matter, so that soil micro-organisms can get to
work. Add this method to restoring grasslands by replanting
long-rooted indigenous varieties, and you have a recipe for vigorous
carbon sequestration in the 20% of the land that is grassland.
how much excess carbon can the soils store? The Rodale study
extrapolates from plots in
four parts of the world to claim from 50% to over 100% of current
emissions. Rattan Lal at Ohio State puts the figure at 10-33%.
However, researchers in prairie grasses say that this could be
increased if one were to extensively replant perennial grasses with
root systems from 1 to 5 meters, rather than conventional carbon
measurements that go only 15-30 cmm. At the conservative end of the
scale, senior scientists Rolf
and Deborah Bossio
at the International Centre for Tropical Agriculture conclude
that soil carbon
sequestration has a limited potential when one takes into account the
variety of possible sites. At best, they say, we can expect 9% of
current emissions the first few decades, with less ability to absorb
CO2 over time. But as Bossio says, “Every bit helps.”
research needs to be done – the field is still new – but clearly
the Rodale Institute study is hyped. One of their test plots, in
Thailand, is done on an “unreported crop” - hardly a
scientifically specified finding. Extrapolating data from this plot,
they get 32 gigatons of of CO2/year of sequestered carbon, precisely
the amount currently emitted. How convenient.
a planetary scale, the ocean stores by far the most CO2, and it has
absorbed about as much as it can, resulting in ocean acidification
that threatens many lime-based species, and the marine foodchain
itself. This happens without our engineering anything. With a
return to more traditional organic farming, including a hugely
increased role for biochar, extensive use of HPG grazing techniques,
and an all-out effort to restore perennial prairie grasses, a
significant portion of current CO2 emissions could be stored in
soils, relieving the
beleaguered ocean. And all of this would help feed our growing
population in a way that works to regenerate degraded soils.
these lines, Wes Jackson at the Land Institute in Salinas, Kansas has patiently led a team of researchers who are back-crossing
perennial prairie grasses to produce seed
kernels big enough to harvest.
I heard him in conversation
with Wendell Berry at a food and spirituality conference at Duke a
few years back, and he was an inspiration.
advance agenda for the COP 21 gathering in Paris does not indicate
that soil carbon storage is being highlighted as a significant
strategy to sequester CO2. The focus is on reducing emissions
(mitigation) and paying the costs of adaptation for the poor
countries already hit by climate change. Hopefully it will emerge
from the dark ecological underground as a robust competitor to the
technocratic agenda, amplifying the highly compromised REDD forest carbon market mechanism. We all await - with a mixture of eagerness and
dread - the results of this key moment in planetary history.
whatever happens in Paris to move the “demand side” onto the
table (i.e CO2's destination, rather than its sources, or
“supply”),with agroforestry and silviculture taking the place of
unaffordable CCS, world powers will not sit idly by if sequestration
lags behind the worrisome rise in levels of emissions. Current
national plans to limit emissions put the world on a trajectory to 3
degrees C of warming, which is double the maximum safe level, and
would assure a runaway climate system, unless we can find a sink
beyond the maxed-out oceans for the relentless stream of CO2. Soil
carbon sinks can be optimized, but the research does not make me
confident that this will be sufficient to the task.
I submit that methods to reduce incoming solar radiation are going to
remain on the table, hopefully with increasing levels of public
discussion, so that all parties are clearly represented, and sober
decisions made. At least nobody is still seriously interested (i.e.
with their checkbooks ready) in the pipedream of CCS that was long
encouraged by fossil fuel companies, so we wouldn't be so concerned
about current emissions. You know, just pump it under the ground, or
to the bottom of the oceans, and we can forget about it.