Methodology

How estimates are produced

The SEEG 6.0 estimates cover GHG emissions in Brazil and in each of the states and federal districts from 1970 to 2017 for all sectors, with the exception of land use change, covering the period from 1990 to 2017.

Also presented in this collection is a beta version of the municipal scale estimates for all municipalities in the State of São Paulo for the period from 2007 to 2015.

The methodological basis of the SEEG estimates is the 3rd Brazilian Inventory of Anthropogenic Greenhouse Gas Emissions and Removals, published by the MCTI in 2016.

Without the official emissions inventories and their baseline reports, it would not be possible to develop this Climate Observatory initiative, since the vast majority of the specific emission factors were calculated in the inventory process by teams of dozens of institutions, involving hundreds of researchers and experts.

The SEEG methodology was published in the journal Nature in May 2018.

Elaboration of estimates step by step

For each sector a calculation routine was created that reproduces the inventory work for each of the reported years (eg, 1990, 1994, 2000, 2005, 2010). Next, we look for activity data that allow us to estimate the evolution of the emissions considering the emission factors of the inventory. Dozens of public and private institutions are consulted to gain access to activity data.

In order to ensure the possibility of repeating estimates calculated by any interested party, only data obtained from publicly and free of charge sources are used, including data available via the internet or publicly accessible libraries.

When the activity data are not available or incomplete, several strategies are used to obtain
the estimates, including the search for reference values, trend lines, correlation with data
from other activities, among others.

Each team spent the following steps basic:

1º. Review of the IPCC methodology and inventory, including reading all reference reports prepared for the third inventory.

2º. Recovery of Inventory evaluation tables to understand and test the form of application of emission factors. In the process, the sheets were redone and systems for calculating, using the 3rd Inventory database, with the aim of replicating the data according to the methodology of description reference reports.

3º. Activity data collection and update components for emission factors. The goal is to raise the updated information whenever possible, with the same sources of inventory, since the data are available for free.

4º. Identification data gaps and defining auxiliary calculation formulas to fill the gaps. When there is gaps in the data required to use the original emission factor in the original format, auxiliary emission factors are used, usually by means of emission correlation analysis and activity level, based on this data. This phase also defines the emission allocation criteria for the states.

5º. Submission and validation of methodology and data, technical seminars, conducted with experts and technicians from the Climate Observatory-member institutions, in order to review the various stages of work.

6º. Review and analysis of data quality. Finally, all data are evaluated according to the quality of emission factors and activity data used. Are identified points that should be improved in future surveys, including a review of methods and data by experts from different sectors.

Alocation by Ested and Federal District

Since version 2.0, released in 2014, SEEG includes the allocation of emissions estimates for states and Federal District, where possible. The proportion of emissions that could be allocated is growing every version. In SEEG 5.0 for the year 2016 it was possible to allocate 96.4% of Brazilian emissions by states and Federal District. Only 3.6% of the emissions have not being allocated.

Since version 2.0, released in 2014, SEEG includes the allocation of emissions estimates for states and Federal District, where possible. The proportion of emissions that could be allocated is growing every version. In SEEG 5.0 for the year 2016 it was possible to allocate 96.4% of Brazilian emissions by states and Federal District. Only 3.6% of the emissions have not being allocated.

GHG scope

Estimates include emissions of all gases considered in the official national inventories including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), which account for over 99% of carbon equivalent (CO2e) emissions, and others like HFCs and SF6.

GWP or GTP?

There are two main approaches for determining the carbon equivalent: GWP (Global Warming Potential) and GTP (Global Temperature Change Potential). The first considers the influence of gases in changing the Earth’s energy balance and, second, the influence in the temperature rise. Both are measured for a period of 100 years, being more commonly used the GWP.

The table below shows the equivalence between the greenhouse gas emissions estimates included in this study.

In the database available on the OC SEEG portal can be found all the data also in CO2 and GTP both the metric of the second IPCC Assessment Report (AR2) as as well the fourth and fifth IPCC Assessment Reports (AR4 and AR5).

The possibility of obtaining data in these different metric is important to be able to make analyzes and comparisons with this 3rd national inventory (uses IPCC AR2), Brazilian NDC to the Paris Accord (uses IPCC AR5) and inventories in developed countries (use IPCC AR4).

Table: Equivalent to GWP and GTP carbon (IPCC AR2)

Gs GTP-100 GWP-100
CO2

1

1

CH4

5

21

N2O

270

310

HFC-125

1.113

2.800

HFC – 134a

55

1.300

HFC – 143a

4.288

3.800

HFC – 152a

0

140

CF4

10.052

6.500

C2F6

22.468

9.200

SF6

40.935

23.900

Table: Equivalent to GWP and GTP carbon (IPCC AR5)

Gs GTP-100 GWP-100
CO2

1

1

CH4

4

28

N2O

234

265

HFC-125

12,700

12,400

HFC – 134a

94

677

HFC – 143a

967

3,170

HFC – 152a

201

1,300

CF4

2,500

4,800

C2F6

19

138

SF6

8,040

6,630

Emissions gross and net

The estimates of gross emissions of gases estufa do not consider carbon dioxide removal by land use changes, that is, the amount of carbon gases fixed by growth of vegetation. When the removals are considered estimates are net emissions (emissions minus removals).

The IPCC guidelines for national inventories provide the rules for accounting of anthropogenic emissions and removals of greenhouse gases for inventory purposes. In the Brazilian inventory, in addition to considering forest restoration, regeneration of pastures and others as carbon sinks, it was also considered as anthropogenic the carbon stocks in natural forests increases when located in protected areas or indigenous lands.

In fact, unprotected forests also can capture CO2 if they are in the natural renewal process, as well as forests in protected areas can emit CO2 if they are in the process of degradation. The enormous volume that can represent – almost 400 million tons of CO2 – 20% of current emissions – may create a distortion in the emissions data.

From a conservative approach, the OC option was to prioritize the dissemination of gross emissions data in SEEG. In the internet data base it’s also available the information on removals and net emissions according to the criteria used in the 3rd Brazilian emission inventory.

The estimates of SEEG also was do not incorporate the discount by emission reduction certificates arising from Clean Development Mechanism (CDM). The total in Brazil in the period 2005-2014, amount about 370 million tons of CO2e (accumulated period).

Emissions of Shipping and Air Transport International (Bunkers)

SEEG has also calculated separately (available for consultation in the site database) emissions data by International maritime and air transport which, as a rule, should be reported separately, as refer to emissions that could be assigned to more than one country. These data are presented in the database as “bunker”.

Emissions and removals not included in the National Inventory (NCI)

The National Inventory does not consider carbon emissions and removals in the soil due to agriculture management practices. As these emissions and removals are key in the account of the Brazilian INDC (commitments in the Paris Agreement) since SEEG 4.0 it is presented separately (available for consultation in the site database) emissions and removals estimations derived from to quality pasture (degraded or well managed), application of tillage techniques (which help capture carbon in the soil), forest plantations and livestock farming integration. In the data base the data is identified as NCI Emissions and NCI Removals (Not Contemplated in Inventory).

Transition Matrix Approach to Land-Use Change (NEW-BETA)

Emissions estimates and removals by land use changes use deforestation data as a proxy for emissions due to the lack of updated annual land use change data.

The MapBiomas project, another initiative of the Climate Observatory, published in 2018 annual maps of land cover and land use in Brazil from 1985 to 2017. Based on these, the SEEG team tested the estimates of emissions and GHG removals based on the matrices the MapBiomas maps and the emission factors of the 3rd Inventory.

The data are presented preliminarily on the platform and will be validated over the next few
months. Once validated, they will become the standard method of SEEG estimates in future
collections.

Emissions by different sectoral arrangements

Total emissions of greenhouse gases are computed in this study in five sectors defined by the guidelines of the Intergovernmental Panel on Climate Change (IPCC) for national inventories.

In order to get a more accurate picture and complete the representation of certain sectors of the economy was an accomplished pilot organization of the information emissions for different sectors / economic activities.