Greenhouse gas balance from cultivation and direct land use change of recently established sugarcane (Saccharum officinarum) plantation in south-central Brazil

The greenhouse gas (GHG) balance or carbon footprint of biofuels, generally calculated by life cycle assessments (LCA), is heavily influenced by the modeling of land use changes (LUC).This includes direct land use changes (DLUC) and indirect land use changes (ILUC).Various methodical approaches for the integration of ILUC in LCA have recently evolved.In this study several approaches for calculating ILUC and the effects on GHG balance are compared.These are economic modeling, deterministic modeling and regional modeling.Papers published on this topic since 2007, when the ILUC debate began, are reviewed considering the following main criteria: methodological approach, uncertainties of assumptions, and the level of the GHG emissions due to ILUC.The results show that the existing approaches lead to strongly divergent results.This is due to uncertainties about relevant assumptions, e.g. the methods of linking commodity prices to ILUC, assumptions about yields, soil carbon contents, and the effect of by-products.These uncertainties and other methodological inconsistencies, e.g. the allocation issue with respect to displacing vs. displaced crops, imply that further research is needed and that current methods are not robust enough for adoption in regulation.

As proposed by United Nations Environment Programme (UNEP)-Society for Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative (Mila i Canals et al., Int J Life Cycle Assess 18:1265–1277, 2007 and Koellner et al., Int J Life Cycle Assess 18:1188–1202, 2013), the impacts of land occupation should be studied in comparison to a baseline. Regardless of these guidelines, a land use baseline is often ignored in agro-bioenergy life cycle assessment (LCA) studies. This paper tests the appropriateness and significance of applying natural regeneration as a land use baseline for assessing the greenhouse gas (GHG) balances of agro-bioenergy in Finland. In the land use baseline applied, the land is assumed to be left to regenerate toward its natural state, which, in Finland, would most probably be some sort of forest. The foregone carbon stock of the natural regeneration baseline was estimated based on the literature. The GHG balances were studied by comparing the cumulative warming impacts of the dynamic biomass carbon cycle of the agro-bioenergy production system and the defined baseline over a given time horizon varying from 0 to 100 years. The significance of the results is illustrated by comparing them to other GHG emissions related to bioenergy. The results depend significantly on the agro-bioenergy yields and the carbon sequestration rate assumed in the natural regeneration baseline scenario. The GHG balances may be of the same magnitude as GHG emissions due to indirect land use changes resulting from market-mediated impacts, life cycle emissions of fossil fuels, and relative reduction in carbon stocks due to forest harvesting for bioenergy. Ignoring a dynamic land use baseline results in misleading conclusions on the GHG balances of land occupation, including agro-bioenergy, due to ignorance of foregone carbon sequestration. Thus, the interpretation of the results and conclusions provided in the vast number of agro-bioenergy LCA studies relying on biomass carbon neutrality should be reassessed. Besides bioenergy, the issue of land use baseline is relevant for any provision service function of land occupation. The foregone carbon sequestration is, however, highly uncertain and thus speculative.

Farm-scale greenhouse gas balances, hotspots and uncertainties in smallholder crop-livestock systems in Central Kenya

The greenhouse gas (GHG) balance or carbon footprint of biofuels, generally calculated by life cycle assessments (LCA), is heavily influenced by the modeling of land use changes (LUC). This includes direct land use changes (DLUC) and indirect land use changes (ILUC). Various methodical approaches for the integration of ILUC in LCA have recently evolved. In this study several approaches for calculating ILUC and the effects on GHG balance are compared. These are economic modeling, deterministic modeling and regional modeling. Papers published on this topic since 2007, when the ILUC debate began, are reviewed considering the following main criteria: methodological approach, uncertainties of assumptions, and the level of the GHG emissions due to ILUC. The results show that the existing approaches lead to strongly divergent results. This is due to uncertainties about relevant assumptions, e.g. the methods of linking commodity prices to ILUC, assumptions about yields, soil carbon contents, and the effect of by-products. These uncertainties and other methodological inconsistencies, e.g. the allocation issue with respect to displacing vs. displaced crops, imply that further research is needed and that current methods are not robust enough for adoption in regulation.

Greenhouse gas balances and land use changes associated with the planned expansion (to 2020) of the sugarcane ethanol industry in Sao Paulo, Brazil

BackgroundFinland’s national Climate Act contains a target for carbon neutrality by 2035. Achieving this target not only depends on the effective implementation of emission reductions, but to a large part on the forest carbon sink. A recent publication of the Government’s analysis, assessment, and research activities highlights a potential disparity in forest land greenhouse gas (GHG) balance estimates by the ex-ante scenario model used in the National Energy and Climate Plan (NECP), and the ex-post GHG inventory methodology used for creating an official record of emissions and removals. Better methodological compatibility is needed to answer a key question: How large will the forest carbon sink be in different scenarios? This study is a first attempt to show the usefulness of applying the GHG inventory calculation approach to predict the forest carbon sink.ResultsIn this study, we introduce a tool that can be used to estimate the GHG balance for forest land, what we call a “synthetic inventory”, and validate it by comparing outputs against historical data reported in Finland’s GHG inventory. Second, we use it to predict GHG balances in year leading up to 2035 at various roundwood and forest residue harvest rates. The tool can replicate forest GHG balances for forest land with an average annual error of 1.0 Mt CO2, representing 4% of the average annual forest carbon sink. We estimate the forest GHG balance in 2035 to be around 3, -15, -32 Mt CO2eq at levels of total annual drain 92, 80, 70 Mm3 respectively.ConclusionsAccording to our calculations the forest land net GHG balance in 2035 is approximately 12 Mt CO2eq higher than what is presented in Finland’s NECP. Conceptual differences between how GHGI methodologies and scenario models estimate living biomass gains and losses contribute to this outcome, in addition to uncertainties associated with both approaches. The tool presented here shows agreement with the National Inventory Report 2023 approach for forest land, and it can be quickly updated to fit new data.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13021-025-00307-2.

Comparing energy balances, greenhouse gas balances and biodiversity impacts of contrasting farming systems with alternative land uses

Greenhouse gas assessment of soybean production: implications of land use change and different cultivation systems

Spatial modelling provides a novel tool for estimating the landscape level distribution of greenhouse gas balances

The global carbon neutrality challenge places a spotlight on forests as carbon sinks. However, greenhouse gas (GHG) balances of wood for material and energy use often reveal GHG emission savings in comparison with a non-wood reference. Is it thus better to increase wood production and use, or to conserve and expand the carbon stock in forests? GHG balances of wood products mostly ignore the dynamics of carbon storage in forests, which can be expressed as the carbon storage balance in forests (CSBF). For Germany, a CSBF of 0.25 to 1.15 t CO2-eq. m−3 wood can be assumed. When the CSBF is integrated into the GHG balance, GHG mitigation substantially deteriorates and wood products may even turn into a GHG source, e.g., in the case of energy wood. In such cases, building up forest carbon stocks would be the better option. We conclude that it is vital to include the CSBF in GHG balances of wood products to assess the impacts of wood extraction from forests. Only then can GHG balances provide political decision makers and stakeholders in the wood sector with a complete picture of GHG emissions.

Balance and saving of GHG emissions in thermochemical biorefineries

Reductive soil disinfestation (RSD) is proposed as a pre-plant, non-chemical soil disinfestation technique to control several soilborne phytosanitary issues. However, limited information is available on the evaluation of greenhouse gas (GHG) balance and soil quality during the soil remediation process as affected by RSD method. A 44-day field experiment including four different treatments was conducted to investigate the effects of conventional RSD and field-aged biochar-amended RSD on GHG balance and soil quality in a degraded vegetable field. Results showed that the conventional RSD application can significantly decrease the soil nitrate (NO3-) concentrations and electrical conductivity (EC) and oxidation-reduction potential (Eh) by 51.4-67.3%, 5.3-23.6%, and 10.9-15.1%, respectively, while significantly increase soil pH and cation exchange capacity (CEC) by 0.37-0.42units and 7.8-32.2%, respectively, in relation to the control (CK). Compared with the conventional RSD treatment, aged biochar-amended RSD significantly reduced soil NO3- concentrations, EC and Eh. No significant differences on CH4 emissions were observed among all the treatments during the experimental period. However, the conventional RSD application significantly increased the cumulative nitrous oxide (N2O) and carbon dioxide (CO2) emissions by 66.2-124.7% and 64.3-130.0%, respectively, and thus resulted in a significant GHG balance of 64.1-130.1% in relation to the CK. On the contrary, although resulted in more N2O emissions compared with the conventional RSD treatment, aged biochar-amended RSD significantly reduced the cumulative CO2 emissions and thus had an overall decrease in GHG balance by 20.7-28.7%. Therefore, aged biochar-amended RSD can simultaneously achieve lower GHG balance and better improvement of soil quality in degraded vegetable field, and thus can be utilized as an effective technology for soil remediation in intensive vegetable production.

Abstract. This study investigated differences in the magnitude and partitioning of the carbon (C) and greenhouse gas (GHG) balances in an age sequence of four white pine (Pinus strobus L.) afforestation stands (7, 20, 35 and 70 years old as of 2009) in southern Ontario, Canada. The 4-year (2004–2008) mean annual carbon dioxide (CO2) exchanges, based on biometric and eddy covariance data, were combined with the 2-year means of static chamber measurements of methane (CH4) and nitrous oxide (N2O) fluxes (2006–2007) and dissolved organic carbon (DOC) export below 1 m soil depth (2004–2005). The total ecosystem C pool increased with age from 46 to 197 t C ha−1 across the four stands. Rates of organic matter cycling (i.e. litterfall and decomposition) were similar among the three older stands. In contrast, considerable differences related to stand age and site quality were observed in the magnitude and partitioning of individual CO2 fluxes, showing a peak in production and respiration rates in the middle-age (20-year-old) stand growing on fertile post-agricultural soil. The DOC export accounted for 10% of net ecosystem production (NEP) at the 7-year-old stand but <2% at the three older stands. The GHG balance from the combined exchanges of CO2, CH4 and N2O was 2.6, 21.6, 13.5 and 4.8 t CO2 equivalent ha−1 year−1 for the 7-, 20-, 35- and 70-year-old stands, respectively. The maximum annual contribution from the combined exchanges of CH4 and N2O to the GHG balance was 13 and 8% in the 7- and 70-year-old stands, respectively, but <1% in the two highly productive middle-age (20- and 35-year-old) stands. Averaged over the entire age sequence, the CO2 exchange was the main driver of the GHG balance in these forests. The cumulative CO2 sequestration over the 70 years was estimated at 129 t C and 297 t C ha−1 year−1 for stands growing on low- and high-productivity sites, respectively. This study highlights the importance of accounting for age and site quality effects on forest C and GHG balances. It further demonstrates a large potential for net C sequestration and climate benefits gained through afforestation of marginal agricultural and fallow lands in temperate regions.

The traditional upscaling approach to greenhouse gas (GHG) emission estimates of inland waters is imprecise, but more precise methods based on environmental drivers are a longstanding challenge. Mexico lacks GHG emission estimates for its inland waters, and only sparse but scientifically validated information is available. This study provides the first GHG emission estimates from Mexican inland waters using 4275 GHG flux measurements from 26 distinctive waterbodies and one local and another global surface area dataset (INEGI and HydroLAKES). GHG emission factors were calculated and subsequently upscaled to estimate total national GHG emissions from the inland waters and compare to other emission measures based on mean global emission factors or size-productivity weighted (SPW) models. Mean (standard error) annual fluxes from all inland waters were 2.2 (5.3) kg CO2 m−2 yr−1, 0.6 (1.14) kg CH4 m−2 yr−1, and 1.0 × 10−3 (6.0 × 10−4) kg N2O m−2 yr−1. Estimates for natural waterbodies are annual average release rates between 74 (87) and 139 (163.23) Tg CO2eq while artificial waterbodies reach between 32 (2) and 21 (21) Tg CO2eq according to INEGI and HydroLAKES datasets, respectively. Considerable uncertainty was determined in the calculated mean emission factor, mostly for anthropogenic emissions. Waterbody area and chlorophyll a concentration were used as proxies to model CO2 and CH4 fluxes through regression analysis. According to SPW and IPCC models, computed mean annual CH4 emission factors were close to our estimates and exhibited a strong influence from eutrophication. In a likely scenario of increased eutrophication in Mexico, an increase in total net emissions from inland waters could be expected.

Greenhouse gas balance and carbon footprint of beef cattle in three contrasting pasture-management systems in Brazil