Geoscience Reference
In-Depth Information
The contribution of agriculture to global GHG emissions
ranges from 5.1 to 6.1 Gt CO
2
-eq. The global potential of ara-
ble and permanent cropping systems to sequester is 200 kg C
ha
−1
year
−1
and pasture systems is 100 kg ha
−1
year
−1
; the world's
carbon sequestration will amount to 2.4 Gt CO
2
-eq. year
−1
(Lal,
2004a; Niggli et al., 2009). This minimum scenario for a con-
version to organic farming would mitigate 40% of the world's
agriculture GHG emissions (Niggli et al., 2009). The sequestra-
tion rate on arable land adopting organic farming with reduced
tillage techniques will be 500 kg C ha
−1
year
−1
, which will
contribute 65% mitigation of the agricultural GHG and, thus,
total global organic mitigation would be 4 Gt CO
2
-eq. year
−1
.
This indicates that application of sustainable management tech-
niques to build up soil organic matter have the potential to bal-
ance a large part of the agricultural emissions although their
effect over time may be reduced as soils are built up (Foereid
and Høgh-Jensen, 2004). By a conversion to organic farming,
another approximately 20% of the agricultural GHG could be
reduced by abandoning industrially produced nitrogen fertilis-
ers as is practiced by organic farms. This encouraging figure
strongly supports the reality of low GHG agriculture and the
possibility of climate neutral farming.
1.10
Agricultural GhG mitigation
economic potential
Estimates of agricultural mitigation potential at various assumed
carbon prices for N
2
O and CH
4
(not for soil carbon sequestra-
tion) were worked out (Anonymous, 2001b, 2006a,b; McCarl
and Schneider, 2001; Manne and Richels, 2004; DeAngelo et
al
.,
2006; Rose et al., 2007; Smith et al
.,
2007b). It was esti-
mated that the economic mitigation potential for soil carbon
sequestration is 27 US$/tCO
2
-eq. (Manne and Richels, 2004).
The 2030 global economic mitigation potential of 1500-4300
MtCO
2
-eq. year
−1
is at carbon prices of 20-100 US$/tCO
2
-eq.
(Smith et al
.,
20 07b).
1.11
Barriers and opportunities/implementation
issues
Changes in climate may add stress to local and regional agri-
cultural economies already dealing with long-term economic
changes in agriculture. In addition, there may be barriers to adap-
tation that limit responses such as the availability of and access to
