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
252
Land use change - GHG emissions from food and feedstuffs
Stefan Hörtenhuber 1,2,* , Michaela Theurl 1 , Thomas Lindenthal 1,3 ,Werner Zollitsch 2
1 Research Institute of Organic Agriculture (FiBL) Austria
2 University of Natural Resources and Life Sciences Vienna, Department of Sustainable Agricultural Systems
3 University of Natural Resources and Life Sciences Vienna, Centre for Global Change and Sustainability
Corresponding author. E-mail: stefan.hoertenhuber@fibl.org
ABSTRACT
Land use change (LUC) is assumed to be a major contributor to global CO2 emissions. Despite its great impact on global greenhouse
gas (GHG) emissions, LUC is hardly incorporated into GHG estimations for food and feedstuffs for various reasons related to methodological
limitations. This contribution outlines a method which can be used to derive direct and indirect emissions from LUC on
the national level for specific crops within a given accounting period for allocation. LUC-related emissions are restricted to physically
occurring fluxes; ten or 20 years are identified as suitable accounting periods for overall LUC-related emissions. Primarily, this
contribution compares effects of different methods on the impact of emissions from LUC on the overall results for products’ GHG
emissions. As a result, we suggest the use of methods which allow for a direct, product-related allocation as this is probably the only
way to quantify mitigation strategies for LUC-related GHG emissions.
Keywords: land use change, greenhouse gas emission, GHG, food, feedstuffs
1. Introduction
Land use change (LUC) and – to a much lesser extent – land use (LU) are assumed to be one of the major
contributors to global CO2 emissions, contributing 23% to the increase in atmospheric CO2 concentration
during the last 250 years (Hörtenhuber et al., 2011a). Accordingly, studies which quantify emissions from
the production of food and feedstuffs or bio-energy will underestimate the increase of the CO2 concentration
in the atmosphere by more than 20% on average unless they account for relevant emissions occurring from
LUC and LU (LULUC). Despite the great impact on global greenhouse gas (GHG) emissions and thus on
global warming, LULUC is hardly incorporated into estimations of the global warming potential (GWP) in
life cycle assessments and into current carbon footprints (CF) in previous studies dealing with the production
of food and feedstuffs. Various methodological problems are among the most important reasons for this.
Literature sources link methodological limitations to lacking information on aspects such as regions of origin
for imported food and feedstuffs, the nature of land before conversion, the onset of LUC-related emissions
and their temporal progression as well as debatable accounting periods for depreciation of LUC-emissions
(see e.g. Dalgaard et al., 2008).
This paper aims at contributing to closing methodological gaps and particularly to deriving reasonable
accounting periods in order to enable a strictly product-related inclusion of emissions from LULUC
Primarily, results for product-related GHG emissions from LULUC are compared to results derived with
other methods and to a basic variant, which does not account for LUC-related emissions.
2. Methods
For the estimation of GHG emissions, information on characteristics of supply chains and on specified
regions of origin of raw materials is often available on a regional scale. Therefore, a product- and regionrelated
approach should be applicable for emissions occurring from the supply chains of most products.
Concerning a methodology which enables a product-related inclusion of emissions from LUC (see
Hörtenhuber et al., 2011a), information was derived from modelling and a literature review. It was concluded
that system boundaries should be defined broadly in the estimation of GHG-emissions from agricultural production.
CO2-neutrality for emissions from LUC exists only theoretically, as the storage of released carbon
occurs over substantial time periods and not necessarily in spatial proximity. Hence, besides fossil CO2 emissions,
CO2 from the degradation of above-ground biomass plus soil organic carbon from LUC and LU (including
below-ground biomass from cleared vegetation) is assessed herein.
Hörtenhuber et al., (2011a) suggested that GHG emissions which CF and GWP accounted for should be
restricted to physically occurring fluxes of GHGs which are related to a specific product. Consequently, we
exclude hypothetical or prospective fluxes such as a ‘loss of sink function’ (Kool et al., 2009), which may be
imposed to quantify a farmlands’ effect of reduced sink capacity as compared to natural vegetation. Likewise,
we do not apply a concept of land use impact to our product-specific calculation of LUC emissions, as
was described in Milà i Canals et al., (2007) and Müller-Wenk and Brandão (2010). The main reason for this
is that this concept also uses hypothetical pathways for emission fluxes from soil organic carbon (SOC). The
method applied herein and described in Hörtenhuber et al., (2011a) includes estimated emissions from LUC