LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 3A: LAND USE CHANGE 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
SBME shows similar results for the variants (c) ‘product-related LUC emissions’ and (d) ‘emissions from a
land use impact method’, the results show great differences, when differentiated for LU and LUC. The reason
for the differences is that in variant (d) according to Müller-Wenk and Brandão (2010) low LUC-related
emissions go along with high rates of carbon losses from LU. From our point of view, this constitutes an
underestimation of emissions from land transformation (LUC), while overestimating the emission effect of
occupied land by assuming that agricultural land use prevents atmospheric carbon from being sequestrated in
terrestrial sinks again. In fact, a notable part of the huge amount of CO2 emitted after a LUC is sequestrated
in natural (‘residual’) terrestrial sinks, such as natural tropical forests (Denman et al., 2007) and does not stay
in the atmosphere until the occupation of the land is abandoned.
According to Vellinga et al., (2011), emissions from LUC should be derived from average global emissions.
The authors describe LUC emissions from single crops as useless and that direct and indirect LUC
cannot be separated, as total human consumption of all commodities is the driver for LUC. Contrarily, our
approach differentiates direct and indirect emissions, as direct and national indirect LUC emissions should be
applied to specific crops, which expanded in specific regions. A comparison of our product-related LUC
emissions to global average LUC emissions (Vellinga et al., 2011) shows a difference in the same order of
magnitude as are described for other GHG emissions (from soil, fuels, etc.). On the one hand, for the case of
European grains (e.g. barley in Fig. 1) the inclusion of globally derived LUC values leads to an overestimation
of GHG emissions from LUC on average and especially in areas, where LUC-related CO2-fluxes had
occurred long ago. For this case, on-going changes in SOC, i.e. emission or sequestration due to LU, should
be reported, but in reality hardly any great losses of SOC can be reported as they usually occur only after
LUC. On the other hand, the global average LUC emissions could underestimate LUC-related CO2 emissions
if huge amounts of CO2 are emitted after a LUC and before a new equilibrium in SOC has been established.
Furthermore, Vellinga et al., (2011) characterise the land use per unit of crop harvested as a key item and
promote their method as being simple and robust while avoiding problems of double counting and displacement.
They refer to an adequate description of their method’s results concerning efficiency (i.e. low yields or
bad feed conversion show high LUC emission). From a global point of view, efficiency of land use (described
by yield per ha) is certainly partially indirectly related to LUC, but on the other side the land demand
of a specific product from a specific region occupying an above-average area of land per product unit is not
automatically related to LUC within a relevant period. In contrast to Vellinga et al., (2011), we assume that
indirect LUC is not only connected to a low productivity per unit of land used, but also to market dynamics
which influence land demand, as do changes in consumption habits and the growing demand for bioenergy
and additional drivers.
The most debated concern about the use of direct LUC emission methods (e.g. applied in BSI, 20011 is
the derivation of a suitable accounting period (also termed depreciation or amortisation period; see Ponsioen
and Blonk, 2012). Herein, we describe an answer to this controversial issue, which is based on soil-related
and atmospheric carbon cycles. Hörtenhuber et al., (2011a) suggested two default periods for LUC-related
accounting: 10 and 20 years. For the Brazilian soybeans used as feedstuff, LULUC-related emissions will
decrease by about 23% if 10 instead of 20 years are implemented, mainly due to a reduced prevalence of
soybean production on newly deforested land. Short accounting periods would lead to the phenomenon that
converted areas are relieved from LUC-related emissions after a short time period. This would lead to indicating
a ‘cleaner’ production after LUC-related emissions had peaked markedly, although the majority of the
released CO2 still remained in the atmosphere. The estimation of product-specific emissions from LULUC
which includes substantially longer accounting periods than used herein, would result in lower LUC-related
emission loads for e.g. feedstuffs imported from Latin-America or from other regions with a high share of
land recently converted.
Due to its high global relevance, emissions from LUC need to be included in the estimation of CF and
GWP, whenever great quantities of (LU)LUC-burdened inputs, such as extracted soybean meal, are used.
This can be illustrated for European meat production systems, which rely on high quantities of imported
LULUC-burdened inputs; for example, the substitution of feedstuffs loaded with LUC-related emissions
(particularly extracted soybean meal) would lead to an estimated 50% less CO2-eq per kg of broiler carcass
(Hörtenhuber et al., 2011a).
5. Conclusion
We suggest using methods for the estimation of LUC-related emissions which allow for a direct, productrelated
allocation. This is probably the only way to quantify mitigation strategies for LUC-related GHG
emissions, even if they do not integrate indirect transnational LUC-effects. To our opinion methods for calculating
LUC emissions should be based on physically occurring fluxes. Despite our approach of estimating
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