Methodology

METHODOLOGICAL NOTES

For each sector, a calculation routine was developed to replicate the inventory work for each of the reported years (e.g., 1990, 1994, 2000, 2005, 2010). Subsequently, activity data is sought to estimate the evolution of emissions considering the inventory’s emission factors. Dozens of public and private institutions are consulted to obtain access to activity data. To ensure the possibility of replicating the estimates calculated by any interested party, publicly available and free data are used, including data available through the internet or in publicly accessible libraries. When activity data is not available or is incomplete, various strategies are employed to obtain estimates, including searching for reference values, trendlines, correlation with data from other activities, among others.

  1. Methodology and Reference Analysis: Review of IPCC Methodology and Inventory, including reading all reference reports prepared for the 3rd inventory.

  2. Refinement of Tables and Systems: Recomposition of Inventory calculation tables to understand and test the application of emission factors. This includes the reformulation of spreadsheets and calculation systems, using the Inventory’s baseline data.

  3. Activity Survey and Updates: Collection of activity data and update components for emission factors. The goal is to gather updated information, whenever possible, from the same sources as the Inventory, provided the data is publicly and freely available.

  4. Identification of Gaps and Auxiliary Formulas: Identification of data gaps and definition of auxiliary calculation formulas to fill these gaps. When necessary data is missing to use the emission factor in the original format, auxiliary emission factors are employed, usually through an analysis of emissions and activity level correlation, based on Inventory data. During this phase, criteria for allocating emissions by states are also defined.

  5. Presentation and Validation in Technical Seminars: Presentation and validation of the methodology and data in technical seminars with experts and technicians from Climate Observatory member institutions. The aim is to review the different stages of the work.

  6. Review and Data Quality Analysis: Evaluation of data quality based on emission factors and activity data used. Identification of areas that need improvement in future surveys, including a review of methods and data by experts from different sectors.

Since version 2.0, launched in 2014, SEEG includes the allocation of emission estimates by states and the Federal District. The proportion of emissions that could be allocated has been increasing with each version. In SEEG 9.0, for the year 2020, it was possible to allocate 96% of Brazilian emissions by states and the Federal District. Only 4% of emissions were not allocated. For the allocation of emissions by Federal Units, activities generating emissions (e.g., deforestation, fuel consumption for transportation, industrial production, etc.) are used as a reference. The following methodological notes detail how the allocation was generated for each estimated emission item.

The estimates include emissions from all gases specified in the inventories, including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), which account for over 99% of carbon equivalent (CO2e) emissions, and others such as HFCs. There are two main approaches for determining carbon equivalent: Global Warming Potential (GWP) and Global Temperature Change Potential (GTP). The first considers the gases’ influence on Earth’s energy balance. The second considers their influence on temperature increase. Both are measured over a 100-year period, with GWP being more commonly used. In the database available on the SEEG portal of the Climate Observatory, data can be found in both CO2e GTP metrics for the fifth IPCC report (AR5) as well as the second and fourth IPCC reports (AR2 and AR4). The ability to obtain data in these different metrics is important for conducting analyses and comparisons with the 3rd Inventory (uses IPCC AR2), Brazilian NDC (uses IPCC AR5), and inventories of developed countries (uses IPCC AR4).

Table: Carbon Equivalence GWP and GTP (IPCC AR2)

Gas GTP-100 GWP-100
CO2 1 1
CH4 5 21
N2O 270 310
HFC-125 1113 2800
HFC-134a 55 1300
HFC-143a 4288 3800
HFC-152a 0 140
CF4 10052 6500
C2F6 22468 9200
SF6 40935 23900

Table: Carbon Equivalence GWP and GTP (IPCC AR5)

Gas GTP-100 GWP-100
CO2 1 1
CH4 4 28
N2O 234 265
HFC-125 967 3170
HFC-134a 201 1300
HFC-143a 2500 2800
HFC-152a 19 138
CF4 8040 6630
C2F6 13500 11100
SF6 28200 23500

The estimates of gross greenhouse gas emissions do not include the removal of carbon dioxide by changes in land use, i.e., the amount of carbon gases fixed by vegetation growth. By subtracting these removals, the estimates become net emissions (emissions minus removals). The IPCC guidelines for national inventories provide for the accounting, for inventory purposes, of anthropogenic emissions and removals of greenhouse gases. In the Brazilian inventory, in addition to considering forest restoration and pasture regeneration as carbon sinks, increases in carbon stocks in natural forests located in conservation units or indigenous lands are considered anthropogenic removals. It is important to note that unprotected forests may capture CO2 in a process of natural renewal, while forests within protected areas may emit CO2 if they are in a process of degradation. Given the significant amount involved – hundreds of millions of tons of CO2 – this definition can distort emission data. Adopting a conservative approach, the Climate Observatory chose to prioritize the disclosure of SEEG data with gross emissions. In the online database, estimates of removals are also available according to the criteria of the 3rd Brazilian emission inventory, allowing for the estimation of net greenhouse gas emissions in Brazil. Additionally, SEEG estimates did not incorporate discounts for emission reduction certificates from Clean Development Mechanism (CDM) projects. The totals in Brazil, from 2005 to 2014, amount to approximately 370 million tons of CO2e (cumulative for the period).

Data for emissions from international maritime and air transport were also calculated separately (available for consultation on the website’s database). By rule, these emissions must be reported separately as they relate to emissions with responsibility from more than one country. In the database, these data are treated as ‘bunker’ or international emissions.

The National Inventory does not consider emissions and removals of carbon in the soil due to agricultural practices. As these emissions and removals are crucial in the calculation of the Brazilian NDC (commitments in the Paris Agreement), starting from SEEG 4.0, separate calculations are presented (available for consultation on the website’s database) for emissions and removals due to pasture quality (degraded or well-managed), application of no-till techniques (which help capture carbon in the soil), forest plantations, and crop-livestock integration. In the database, they are identified as NCI Emissions and NCI Removals (Not Contemplated in the Inventory).

The total emissions of greenhouse gases are computed in this study within the five sectors defined by the guidelines of the Intergovernmental Panel on Climate Change (IPCC) for national inventories. In order to obtain a more accurate and comprehensive representation of certain sectors of the economy, a pilot project was conducted to organize emission information for different sectors/economic activities.

Until SEEG 7.0, emission and removal estimates for land-use change used deforestation data as a proxy for emissions due to the absence of annual and updated land-use change data in Brazil. The MapBiomas project, another initiative of the Climate Observatory, published annual land cover and land use maps for Brazil from 1985 to 2017 in 2018. Based on these maps, the SEEG team tested calculating greenhouse gas emission and removal estimates based on transition matrices derived from the MapBiomas maps and emission factors from the 3rd Inventory. Starting from SEEG 8.0, the transition matrix method with MapBiomas data was adopted as the standard method for emission estimates. Data using the deforestation proxy method continues to be calculated and provided as an option for users under the name Emissions or Removals Proxy. For municipalities, only the standard method is used.

Last update: 22/12/2023.

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