With the new increases in biofuel production around the world, attention must turn to the potential negative environmental impacts due to altered land use. Previous estimates of these consequences used models that were not geographically nor ecologically specific and led to gross miscalculations. This case study in Brazil projects the effects on the Amazon due to increased biofuel production using a spatially explicit model to project land-use changes caused by that expansion in 2020 (Lapola et al, 2009). New estimates reveal that current methods of land use allocation may create a carbon debt that would take up to 250 years to be repaid, an amount which overcomes the carbon sequestering benefits of biofuels over fossil fuels. — Elena Davert
Lapola, D.M., Schaldach, R., Alcamo, J., Bondeau, A., Koch, J., Koelking, C., Priess, J.A. Indirect land-use changes can overcome carbon savings from biofuels in Brazil. Proceedings of the National Academy of Science 107, 3388–3393.
Currently, Brazil’s government, in conjunction with the biofuel industry, is planning a large increase in the production of biofuels over the next 10 years. With the potential ethanol production increase of 35 (4) x 109 liters in the 2003-2020 period –which equates to a projected indirect deforestation of 121,970 km2 by 2020– there are clear concerns about measuring the consequences of the land-use changes (LUC) associated with this increase. Some of the previous studies focused on the direct land-use changes (DLUC) and the resulting “carbon debt” caused by replacing native habitats with biofuel crops, while others pointed to the probable indirect land-use changes (ILUC) in Brazil caused by future expansion of food and biofuel croplands in other countries such as the United States. Although these studies showed that potential LUC must be taken into account to assess the efﬁcacy of a given biofuel, they were neither spatially explicit, nor did they specifically consider competition between different land uses in view of concurrent food and biofuel demands. Because of this, calculations of the effects of LUC in previous studies are mostly underestimated or incomplete.
In order to create as fully comprehensive estimate of effects due to LUC, Lapola et al used a new spatially explicit modeling framework to project the complete DLUC and ILUC resulting from Brazil’s biofuel production targets for 2020. In addition to being spatially explicit, the new model is also concurrent with increasing food and livestock demands and their demands for land as well. The modeling framework comprises of 3 major components: (1) a land-use/land-cover change model for land-use suitability assessment and allocation; (2) a partial equilibrium model of the Brazilian economy of the agricultural sector for future food demands, livestock demands, and advancement of crop yields due to improved technology; and (3) a dynamic global vegetation model for varying crop and grassland potential productivity driven by climate changes. The competition among land uses –for land resources– is also incorporated into the model based on an evaluation of suitability, hierarchical dominance of major land-use activities (settlement, crop cultivation, livestock grazing), and a land allocation algorithm which looks for land-use pattern stability over multiple land use objectives.
According to the new model, 88% of the DLUC (145,700 km2) due to sugarcane cropland increasing by 57,200 km2 and soybean cropland increasing by 108,100 km2 will take place in areas previously used as rangeland, and the amount of cropland area replaced by biofuels would reach 14,300 km2. The resulting deforestation amounts to only 1,800 km2 of forest and 2,000 km2 of woody savanna, the required payback time for sugarcane DLUC emissions would be 4 years, while the DLUC carbon emissions for soybean biodiesel would not be paid back for at least 35 years. While these numbers are not considerably daunting, the model revealed that ILUC could considerably compromise the GHG savings from growing biofuels, mainly by pushing rangeland frontier into the Amazon forest and Brazilian Cerrado savanna. With an expansion of 121,970 km2 of rangeland into forest areas, and 46,000 km2 into other native habitats due to the expansion of biofuel croplands, the required payback time for GHG emissions increases to 44 years for sugarcane crops and 246 years for soybean crops.
Ultimately, the dramatic costs of ILUC in this study raise the question of whether the common practice of reallocating all displaced rangeland should continue. Changes in current practices will be difficult because not only is animal acquisition currently heavily subsidized in Brazilian cattle ranching, especially in the Amazon region, but very few incentives are provided for the recovery of degraded pastures. Socioeconomic surveys also suggest that technological innovation or the intensiﬁcation of livestock inside the Amazon region may increase the attractiveness of cattle ranching and thus further deforestation. The authors argue that in order to avoid the undesired ILUC caused by biofuels, strategies for increased cooperation between the cattle ranching and biofuel-growing sectors should be implemented by the biofuel sector, and institutional links between these two sectors should be strengthened by the Brazilian government.