Greenhouse gases: What are Scope 1, 2 and 3 emissions?
To develop and implement a decarbonization strategy and corresponding reduction targets, it is first necessary to have a precise understanding of the relevant emission sources. For this purpose, the different greenhouse gas emissions are identified in the various categories: Scope 1, Scope 2 and Scope 3.
The basis for these calculations is the Greenhouse Gas Protocol, also known as the GHG Protocol, a globally recognized, private, transnational set of standards for accounting for greenhouse gas emissions and the associated reporting. The GHG Protocol is used by many companies, non-governmental organizations, or NGOs, and governments.
The development of the GHG Protocol is coordinated by the World Resources Institute, or WRI, and the World Business Council for Sustainable Development, or WBCSD. As a result, the standard is based on scientific foundations and internationally recognized principles of emissions management. The GHG Protocol also serves as a reference for numerous environmental and sustainability standards. Many of these standards, including ISO 14064, are based on the methods and principles of the GHG Protocol or derive their requirements from them.
Basic principles of the GHG Protocol
The GHG Protocol is based on the principles of relevance, completeness, consistency, transparency and accuracy. It covers the greenhouse gases regulated under the Kyoto Protocol: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3).
If a company wants to introduce the GHG standard, it must first define the reporting period and organizational boundaries. It can either account for emissions proportionally according to ownership shares, known as the equity share approach. Or it can account for all greenhouse gas emissions over which it has control, known as the control approach, regardless of whether this is financial or operational control.
Direct and indirect emissions
Once the reporting period and organizational boundaries have been defined, the relevant emission sources are then identified. For companies, these may include the vehicle fleet, heating systems, refrigeration equipment and company-owned power plants. Greenhouse gases emitted from these sources are referred to as direct emissions. All other emissions that originate from sources outside the defined organizational boundaries are referred to as indirect emissions.
Scope 1, 2 and 3
Scope 1 emissions are direct greenhouse gas emissions from sources that are owned or controlled by the respective company. These include, for example, emissions from vehicles, heating systems and power plants operated by the company itself.
Scope 2 emissions are indirect greenhouse gas emissions resulting from purchased energy such as electricity, steam or district heating. Although this energy is consumed by the respective company, it is generated outside the company’s own system boundaries — for example, in power plants that use fossil fuels to generate electricity.
Scope 3 emissions comprise all other indirect emissions caused by the respective company’s activities. They originate from sources that are not owned or controlled by the company. Unlike Scope 1 and Scope 2 emissions, Scope 3 emissions occur along the entire value chain. These emissions are divided into 15 subcategories covering both upstream and downstream activities. Examples include the production and transport of products, business travel by the company’s own employees, commuting to work, and the use and disposal of products at the end of their life cycle. Scope 3 emissions usually account for the largest share of a company’s greenhouse gas emissions and include all activities that are indirectly connected to business operations.
Deutsche Bahn’s climate protection target is based on the Net-Zero Standard of the Science Based Targets initiative (SBTi) and therefore follows a 1.5°C pathway. The SBTi is a renowned non-governmental organization (NGO) that has developed a science-based methodology for setting climate protection targets.
DB has committed to reducing its greenhouse gas emissions across the entire value chain to net zero by 2040. This target has been backed by an implementation plan and validated by the renowned and independent Science Based Targets initiative (SBTi).
The net-zero target adopted by the DB Group covers both direct emissions (Scope 1) and emissions from purchased energy (Scope 2), as well as emissions from the upstream and downstream value chain (Scope 3). Net zero means that all greenhouse gas emissions that are technically feasible and economically reasonable to reduce will be reduced. Only residual emissions that are difficult or otherwise impossible to avoid, up to a maximum of ten percent, will be neutralized — that is, removed from the atmosphere and permanently stored through technical or nature-based solutions.
For Scope 1 and 2, DB has adopted absolute CO2e reduction pathways based on high data quality and SBTi requirements. These include both the net-zero target by 2040 and an absolute interim target by 2034, as required by the SBTi. By 2034, DB will reduce its absolute greenhouse gas emissions in Scope 1 and 2 by 63 percent compared with the 2019 base year — and by at least 90 percent by 2040.
In 2025, around 1.2 million tonnes of CO2e of DB’s GHG emissions were attributable to Scope 1. This includes, for example, exhaust emissions from the operation of diesel locomotives and vehicles, as well as GHG emissions released through the operation of heating and air-conditioning systems in buildings.
DB’s Scope 2 emissions comprise the total energy demand required for traction power and the various operating buildings. The share of renewable energy in the traction power mix is particularly relevant here, as increasing the share of green electricity directly reduces Scope 2 emissions. DB’s Scope 2 emissions amounted to around 2.1 million tonnes of CO2e in 2025. These GHG emissions were calculated using the market-based approach.
Absolute greenhouse gas emissions by Scope 1–3 / in million tonnes CO2e
2025 | 2024 | 2023 | |
|---|---|---|---|
| Scope 1 emissions | 1,2 | 1,1 | 1,1 |
| Scope 2 emissions, market-based | 2,1 | 2,7 | 3 |
| Scope 3 emissions | 7,8 | 6,3 | 8,2 |
Scope 3 includes the Scope 3 categories material to the DB Group: 3.1, 3.2, 3.3, 3.4 and 3.11. In 2025, the Scope 3.4 category was expanded for the first time to include transport-related emissions associated with purchased goods and capital goods.
The Scope 3 challenge
Around two-thirds of Deutsche Bahn’s greenhouse gas emissions arise in Scope 3. Accounting for and managing these emissions is challenging because they include, among other things, GHG emissions from DB’s suppliers and service providers. These emissions occur, for example, in the production of rail vehicles, the construction of infrastructure and the production of food for on-board bistros. They therefore lie outside the Group’s direct sphere of influence, which is why DB depends on intensive dialogue and cooperation with its suppliers and partners to reduce them.
Deutsche Bahn has also adopted the net-zero target for Scope 3 by 2040. Due to the currently limited data quality for a large share of Scope 3 emissions, an absolute CO2e reduction pathway comparable to Scope 1 and 2 — and therefore planning underpinning an interim target — is not yet possible for all Scope 3 categories. For such cases, which also pose challenges for other companies, the SBTi allows alternative target approaches, including the so-called Supplier Engagement Target.
Supplier Engagement Target
With the Supplier Engagement Target, companies that supply DB with goods, services and capital goods are required to set science-based climate protection targets of their own. Deutsche Bahn’s objective is for 66 percent of these suppliers, based on GHG emissions volume, to do so by 2029. This partnership-based strategy not only enables significant reductions in DB’s Scope 3.1 and 3.2 emissions, but also helps make the entire value chain more climate-friendly in cooperation with suppliers.
Fuel- and energy-related activities
Deutsche Bahn has also set an interim target for fuel- and energy-related activities, in particular electricity sold to external parties. By 2034, GHG emissions in Scope 3.3 are to be reduced by 40 percent compared with the 2019 base year. A reduction is also planned for GHG emissions from the use of sold products, in particular fossil fuels sold to external parties: compared with 2019, GHG emissions in Scope 3.11 are to decrease by 63 percent by 2034.
Together, these Scope 3 categories account for around 90 percent of DB’s Scope 3 emissions.
Coordinated climate protection efforts
To achieve its interim targets and net zero by 2040 in Scope 3, Deutsche Bahn needs reliable data from its supply chain. Many emissions already arise during the production of materials and vehicles purchased by DB, or in connection with services used by the company. Deutsche Bahn is therefore improving access to precise emissions data from its suppliers and recording primary data for material commodity groups in a central IT system. In addition, sustainable financing concepts are being developed and GHG emissions criteria are being gradually integrated into procurement processes. New suppliers that provide material goods and services are encouraged to set science-based climate protection targets of their own.
Climate-friendly construction is also an important lever for reducing Scope 3 emissions. For this reason, DB is using lower-emission building materials and materials in pilot projects. In addition to steel and concrete, the focus is also shifting to sustainable construction methods. Standards and planning approaches are also being developed to improve the CO2e balance over the entire life cycle of DB’s structures.
Deutsche Bahn also aims to optimize the procurement and maintenance of its rail vehicles, for example by using recycled materials and ensuring a longer service life.
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