Geoscience Reference
In-Depth Information
financial resources and technical assistance, as well as the avail-
ability of other inputs, such as water and fertiliser. Uncertainty
about the timing and rate of climate change also limits adaptation
and, if expectations are incorrect, could contribute to the costs
associated with transition and disequilibrium. The barriers to
adoption of carbon sequestration activities on agricultural lands
following Smith et al. (2007a) are discussed below.
Maxi mum
storage
Carbon sequestration in soils or terrestrial biomass is a rapid
and cheap available option that needs 15-60 years to reach a
maximum capacity for the ecosystem, depending on manage-
ment practice, management history and the system (West and
Post, 2002; Caldeira et al., 2004; Sands and McCarl, 2005).
Revers ibility
Mostly, agricultural mitigation options are reversible and a
change in management can reverse the gains in carbon seques-
tration. Reduction in N
2
O and CH
4
emissions, avoiding emis-
sions as a result of agricultural energy efficiency gains and
the substitution of fossil fuels by bioenergy are non-reversible
(Smith et al., 2007a).
Baseline
The GHG net emission reduction is assessed relative to a base-
line, but selecting an appropriate baseline is a problem (Smith
et al., 2007a).
Uncer tainty
Complex biological and ecological processes involved in GHG
emissions and carbon storage is complex and less understood
(mechanism uncertainty). This makes investors shy away from
the agricultural mitigation options. Moreover, agricultural sys-
tems exhibit substantial variability between seasons and loca-
tions, creating high variability in offset quantities at the farm
level (measurement uncertainty), which can be reduced by
increasing the geographical extent and duration of the account-
ing unit (Kim and McCarl, 2005).
Displace ment of
emissions
Adopting certain agricultural mitigation practices may reduce
production within implementing regions. However, this ben-
efit may be offset by increased production outside the project
region unconstrained by GHG mitigation objectives reducing
the net emission. 'Wall-to-wall' accounting can detect this and
crediting correction factors may need to be employed (Murray
et al., 2004; Anonymous, 2005b).
trans action
costs
Under an incentive-based system such as a carbon market, the
amount of money farmers receive is not the market price but
