Climate Change Mitigation - Soil Carbon: Science, Management and Policy for Multiple Benefits - page 127

All biological C sinks are inherently
non-permanent, in that organic carbon,
whether in biomass or soils, is subject to
re-emission as CO 2 to the atmosphere if the
management practices that increase C stocks
are reversed or somehow compromised.
Soil C stock accumulations are, in general,
less vulnerable than biomass C stocks to
inadvertent stock losses due to natural dis-
turbances, such as fire and pest outbreaks.
Thus, intentional abandonment or reversal
of the soil C sequestering practices repre-
sents the primary non-permanence risk for
soils. Other challenges to long-term main-
tenance of prescribed practices include
changes in land ownership and incentives
to change cropping practices due to changes
in commodity prices. To the extent that the
adoption of improved practices leads to in-
creased productivity and/or reduced costs
over time (but require incentives to first es-
tablish), risks of non-permanence for many
conservation management practices may be
relatively low - i.e. farmers would have
additional (non-mitigation related) incen-
tives to continue to maintain the practices
long term.
Various approaches have been pro-
posed to adjust for non-permanence, in-
cluding ex ante discounting and leasing or
renting sequestration credits (Murray et al .,
2007), which assume that all additional
stored carbon is re-emitted at the end of the
project/contract period and the value of the
credit is discounted accordingly. The gen-
eral concept with rented or leased credits is
that the buyer assumes liability for emis-
sions of stored carbon after the end of the
contract period, and thus would have either
to renew the lease or to replace it with other
credits or emission reductions. This de-
creases the economic value of SCS-based
activities dramatically, and thus is a strong
disincentive for many agricultural mitiga-
tion projects.
Another approach to reducing non-
permanence risk includes the use of a per-
manence buffer, such as in the Verified
Carbon Standard (VCS, 2013). The VCS
uses a risk assessment approach to rate pro-
jects in terms of their relative risk for non-
permanence in order to establish an amount

of offset credits that are assigned to a pooled
buffer account, which is maintained within
the overall offset registry. Over time, if a
project maintains its integrity and is able to
mitigate the non-permanence risk success-
fully, the number of credits held in the buf-
fer account is reduced. The advantage to the
buffer approach is that the non-permanence
risk is held within the registry so that activ-
ities that have a low risk of non-permanence
are not penalized unduly and full-value
'permanent' credits are issued to the buyer.
To do so, however, requires an increased
monitoring and assessment effort within the
programme to ensure the integrity of the
permanence buffer.
Leakage refers to unintended emis-
sions that occur outside the boundary of a
mitigation project that arise due to the es-
tablishment of the project, thus nullifying
all or part of the emission reductions (or
sink enhancement) achieved by the pro-
ject. For example, an effort to halt deforest-
ation and the accompanying CO 2 emissions
in one location could result in the forest-
clearing activities moving to another loca-
tion, so that emissions are not really reduced
as a result of the project, unless proper
safeguards are in place to prevent leakage.
This type of displaced activity leakage is
most likely to occur for agricultural activ-
ities that involve land-use changes, such as
afforestation of agricultural land or conver-
sion of cropland to grassland reserves,
which reduce or displace the main product-
ive use of the land, such as food or fibre
production. Thus, effective agricultural miti-
gation projects promoting SCS will be those
that maintain or enhance food and fibre
production. This type of approach is also
highly commensurate with objectives to
increase food security and buffer against
the effect of climate change, as discussed
previously in the chapter.

Integrating the Spatial Dimension:
A Mandatory Aspect

The spatial dimension has to be taken into
account since a technical solution could in-
crease emissions at the scale of an individual