Attributional life cycle assessment: is a land-use baseline necessary?

Abstract

Purpose This paper aims to clarify the application of a landuse baseline in attributional life cycle assessment (ALCA) for product systems involving land use, through consideration of the fundamental purpose of ALCA. Currently, there is no clear view in the literature whether a baseline should be used when accounting for environmentally relevant physical flows related to land use. Methods An extensive search of literature was carried out using the key terms 'attributional life cycle assessment' and 'attributional LCA' in the Google Scholar web search engine. Approximately 700 publications were reviewed and summarised according to their type and scope, relevance of land use, key statements and references given for ALCA, and arguments for and against using a baseline in ALCA. Based on the literature review and supplementary literature references, a critical discussion on the use of a baseline and determination of the most appropriate land-use baseline in ALCA is provided. Results and discussion A few studies clearly argued that only absolute (observable) flows without a baseline are to be inventoried in ALCA, while the majority of the studies did not make any clear statement for or against. On the other hand, a land-use baseline was explicitly applied or proposed in a minority of the studies only, despite the fact that we classified land use as highly relevant for the majority of the studies reviewed. Furthermore, the LCA guidelines reviewed give contradictory recommendations. The most cited studies for the definition of ALCA provide general rules for selecting processes based on observable flows but do not argue that observable flows necessarily describe the environmentally relevant physical flows. Conclusions We conclude that a baseline is required to separate the studied parts of the technosphere from natural processes and to describe the impact of land use on ecosystem quality, such as carbon sequestration and biodiversity. The most coherent baseline for human-induced land-use in ALCA is natural regeneration. As the natural-regeneration baseline has typically been excluded, may vary bio-geographically and temporally, and is subject to uncertainties, case studies applying it should be performed so that implications can be studied and evaluated. This is particularly important for agricultural and forestry systems, such as food, feed, fibre, timber and biofuels. Responsible editor: Matthias FinkbeinerElectronic supplementary material The online version of this article (

Response to “Attributional life cycle assessment: is a land-use baseline necessary?”—appreciation, renouncement, and further discussion

“…The truth of this idea can also be seen by considering the aggregation of all national greenhouse gas inventories, which, in principle, approximate to total global anthropogenic emissions and removals (excepting ad hoc exclusions such as international aviation and shipping, military activities etc.). This conception of attributional methods is also consistent with the idea that attributional LCA attributes Bportions of the total pollution and resource consumption flows occurring from the economy as it is at a given point in time to each existing product life cycle^ (Soimakallio et al 2015).…”

“…If the use of such baselines is appropriate for attributional national greenhouse gas inventories, it can be inferred that they are similarly appropriate for attributional LCA. Soimakallio et al (2015) are also entirely correct to conclude that because of the use of baselines, attributional LCAs are not inventories of absolute (observable) emissions and removals, contrary to previous statements made by the present author (Brander et al 2009;Brander and Wylie 2011;Brander 2015). Soimakallio et al (2015) also correctly diagnose one of the reasons for conceptualising attributional methods as inventories of absolute impacts, i.e.…”

“…Soimakallio et al (2015) are also entirely correct to conclude that because of the use of baselines, attributional LCAs are not inventories of absolute (observable) emissions and removals, contrary to previous statements made by the present author (Brander et al 2009;Brander and Wylie 2011;Brander 2015). Soimakallio et al (2015) also correctly diagnose one of the reasons for conceptualising attributional methods as inventories of absolute impacts, i.e. natural baseline emissions from fossil fuel combustion are generally zero, and therefore, anthropogenic and absolute emissions will tend to be identical.…”

“…4 Appropriateness of natural regeneration Soimakallio et al (2015) suggest that natural regeneration is the most coherent baseline for attributional LCA; however, the following illustrative example and discussion raise a number of potential problems.…”

“…If the products from the next 20 years of continued land use are also allocated 20tCO 2 of foregone sequestration, it will be the same 20tCO 2 allocated twice, and so on. One of the arguments cited in favour of a natural regeneration baseline, drawn from Milà i Canals et al (2007), is that Bland occupation postpones natural regeneration of the land, which is an impact that needs to be accounted for ( Soimakallio et al 2015). Although the postponement of natural regeneration is certainly a consequence of continued land occupation, if it is not an anthropogenic impact relative to a natural baseline (as argued above), then it simply does not belong in an ALCA.…”