Baseline Time Accounting Significantly Improves the Climate Impact Assessment of Indirect Land Use Change (ILUC)

CHICAGO and BAGSVAERD, Denmark, Nov. 1, 2012 /PRNewswire/ -- Indirect land use models that forecast the global warming impact of biofuels production incorporate time accounting in a very simplistic way to allocate total carbon emitted from affected land to the volume of fuel produced. The accuracy of accounting for time in these models is severely limited by the currently employed annualization approach: The annualization approach requires the arbitrary projection of future biofuels production over which land use emissions are allocated but fails to incorporate actual land use dynamics such as expanding and contracting agriculture land area.  

A more sophisticated approach to existing time accounting was clearly required and has led to a new time accounting model by Dr. Jesper Hedal Kløverpris and Dr. Steffen Mueller. Kløverpris and Mueller propose their "Baseline Time Accounting Concept" as an integrated part of future ILUC studies.

Baseline time accounting addresses significant shortcomings in ILUC models and when incorporated into those models results in a more accurate assessment of global warming impact. This approach provides ILUC scientists with the ability to isolate the climate impact of biofuels-related land use changes from other land use changes as they play out in the wider dynamic development of the global agricultural area.

Most ILUC models assume a static land use baseline even though it is clear that land use trends differ regionally.  Climate impact estimates are more precise when indirect land use emissions from the conversion of land at the agricultural frontier are compared with emissions resulting from the baseline conversion of the same land.  "As many others, I have always been uncomfortable with the annualization method applied for time accounting in most previous ILUC studies because it is basically arbitrary," stated Dr. Jesper Hedal Kløverpris, co- author of the new baseline time accounting approach. "A more sophisticated approach was required to assess the actual climate impact of indirect land use change. Baseline time accounting is our proposal for a more scientifically rigorous way of dealing with the time issue in ILUC studies as the science is refined."

More specifically, the Kløverpris and Mueller approach incorporates two agricultural land use dynamics missing from previous time accounting models that define the totality of ILUC. The first is accelerated expansion which occurs in regions such as Latin America where agriculture area is expanding. Biofuel production may move up by a year or more the ongoing conversion of land to agriculture. Globally, the agricultural area will continue to expand for some decades, so a piece of land converted as an indirect result of biofuels production today would have come into production at some point anyway. That may not continue to be the case but one of the points with baseline time accounting is to assess biofuels production under the conditions prevailing when the biofuels are produced. If global land use dynamics change, so does the climate impact of ILUC.   

The second dynamic is delayed reversion which addresses ILUC in regions where agricultural land use is declining or farm land is taken out of production. Biofuels production would slow that pace at which the agricultural area is reduced.

Accelerated expansion and delayed reversion together define ILUC in relation to a dynamic baseline throughout the world of agriculture. Kløverpris and Mueller lay out the framework for the estimation of an ILUC emissions factor based on principles also used by the Intergovernmental Panel on Climate Change (IPCC).

The baseline time accounting method was applied to the ILUC studies by Searchinger et al. (2008) and Hertel et al. (2010) and, under current baseline conditions, the method reduced the ILUC emission factors predicted by these studies by 60-70%.

"Baseline time accounting is sensitive to regional land use changes and considers the alternative fate of land brought into production as an indirect result of biofuels production," stated Dr. Jesper Hedal Kløverpris, study author. "The 60-70% reduction in ILUC emission factors when applied to previous studies under current baseline conditions indicates the need for this approach and the need to build it into future research."

Kløverpris and Mueller conclude that if land indirectly affected by biofuel production would have been affected anyway at a later time, omitting this aspect may lead to erroneous conclusions about ILUC.

The peer reviewed study was published in the International Journal of Life Cycle Assessment and it is available at:  http://www.springerlink.com/openurl.asp?genre=article&id=doi:10.1007/s11367-012-0488-6

Dr. Jesper Hedal Kløverpris is an LCA Specialist for Novozymes A/S in Denmark. Dr. Steffen Mueller is the Principal Economist for the University of Illinois at Chicago Energy Resources Center.

SOURCE Jesper Hedal Kloverpris; Steffen Mueller