Researchers create method to calculate impacts of land use changes in Brazil

Scientists have just developed the first tool capable of consistently estimating the impacts caused by land use change (LUC) for the entire Brazilian territory. Created in partnership between Embrapa and the KTH institute, in Sweden, BRLUC is a method capable of estimating carbon dioxide (CO2) emission rates associated with the 64 crops available in the Brazilian Institute of Geography and Statistics database (IBGE).

Researchers believe that the method should become a fundamental source for national carbon footprint and life cycle assessment (LCA) studies. Information on land use change is mandatory in these works, but its calculation is quite complex. Furthermore, these changes tend to represent a considerable portion of greenhouse gas emissions in developing countries. This is the case in Brazil. This increases the importance of a means that provides reliable estimates and that considers Brazilian conditions.

There are several international LUC methodologies and estimates for Brazil, but they generally use global data and assumptions that are poorly representative of the dynamics of Brazilian agriculture. Many do not consider, for example, the existence of more than one harvest per year and the enormous heterogeneity of the national territory. As a result, it is common for the results to be very far from reality and fail to express the sustainability advances implemented in the country.

According to Renan Novaes, analyst at Embrapa Environment (SP) and one of the creators of BRLUC, the methodology was developed following the logic of life cycle thinking and is based on international standards. “Basically, the objective of methods in this line is to estimate which types of land use (agriculture, livestock, forestry or native vegetation) provided area for the expansion of a crop 'X' in the last 20 years. By obtaining percentages of how much each land use has yielded, the CO2 emissions or sequestration that occurred due to this change are calculated and this change in the CO2 balance is attributed to product X”, he details.

Novaes explains that each land use has a different carbon stock and depending on the pattern of change in use, the crop analyzed presents a CO2 emission or sequestration value per hectare. This number is then used to compose the carbon footprint of agricultural products. “The BRLUC method allows this estimate to be made in accordance with international standards, but considering the particularities of Brazil and uses official and more detailed databases”, highlights the expert.

Furthermore, the tool incorporates specificities of tropical agriculture and deals with the scarcity of information on historical land use transitions for each crop. This information is either not available or is very limited in space and time. “To overcome this, we developed scenarios of minimum and maximum emissions over the last 20 years for each crop. Our results show that this variation can be very large and have huge impacts on results and most international standards do not take this into account”, explains Novaes.

The method, by Renan Novaes and Ricardo Pazianotto, of Embrapa Environment, Miguel Brandão (KTH Sweden), Bruno Alves, from Embrapa Agrobiology (RJ), Andre May, from Embrapa Corn and Sorghum (MG) and Marilia Folegatti-Matsuura, from Embrapa Environment, has just been published in Global Change Biology.

They are also available for free download at Embrapa website a computer script that allows anyone interested to run or customize the method and a spreadsheet to consult all results for any crop or state.

Some results were recently presented in seminar aimed at specialists in the field. The data is already being demanded by several institutions that develop carbon footprint and LCA studies. “As the calculation of this factor is complex, experts have to spend a lot of time to obtain these numbers. The method will make this work much easier,” says Novaes.

For Matheus Fernandes, from the Center for Sustainability Studies at Fundação Getúlio Vargas (FGV), the method presented is of enormous importance to the community, as it is aligned with the main international guidelines that deal with the topic and, at the same time, works with a national database. “When considering the country’s characteristics, BRLUC will bring a result that is more faithful to the Brazilian reality and will increase the reliability of diagnoses generated through this method,” believes Fernandes. “There are some issues to be improved, but this is the first step towards consolidating a regionalized method”, considers the specialist.

Otavio Cavalett, from Bioetanol, also learned about this method and considers it to be the result of the efforts of important Brazilian professionals in the environmental field. “The tool will be important not only to internalize global discussions about the climate impacts arising from direct and indirect changes in land use, but also to propose important methodological changes to better represent the specificities of these dynamics of land use in Brazilian agriculture”, says Cavalett .