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Governance Authority
Category: Sustainability and ESG

Greenhouse Gas Emissions

Also known as: GHG Emissions, GHG emissions, greenhouse gases, carbon emissions
Simply put

Greenhouse gas emissions are the release of certain gases into the Earth's atmosphere that contribute to the greenhouse effect, a natural warming process. These gases include carbon dioxide, methane, and nitrous oxide, and they come from sources such as burning fossil fuels for electricity, heat, and other human activities. Emissions are commonly measured in tonnes of carbon dioxide equivalent to allow different gases to be compared on a common basis.

Formal definition

Greenhouse gas emissions refer to the release into the atmosphere of gases, principally carbon dioxide, methane, and nitrous oxide, among others, arising from human activities and natural processes, including the combustion of fossil fuels and land-use change. For measurement and reporting purposes, emissions from different gases are typically aggregated and expressed in tonnes (or larger units such as million metric tonnes or gigatonnes) of carbon dioxide equivalent (CO2eq), which normalizes each gas according to its warming contribution. The scope of what is captured in a given emissions figure varies by methodology and boundary (for example, whether the land sector is included or excluded), so practitioners should confirm the reporting boundary, applicable disclosure framework, and jurisdictional requirements before relying on any specific figure. This entry is educational and does not constitute legal, audit, or compliance advice; whether and how an entity must measure or disclose GHG emissions depends on applicable law, sector, and entity type.

Why it matters

Greenhouse gas emissions have moved from a purely scientific or environmental topic to a core governance and disclosure concern. In many jurisdictions, regulators, listing authorities, and investors increasingly expect entities to measure, manage, and in some cases report their emissions, and the credibility of those figures depends heavily on the reporting boundary and methodology used. Because emissions from different gases are normalized into carbon dioxide equivalent (CO2eq), a single reported number can obscure important choices, such as whether the land sector is included or excluded, making transparency about scope essential to avoid misleading stakeholders.

The scale of the issue explains the attention it receives. According to Our World in Data, global greenhouse gas emissions are on the order of tens of gigatonnes of CO2eq per year, and burning fossil fuels for electricity, heat, and related activities is identified by the U.S. Environmental Protection Agency as the largest source of emissions from human activities in the United States. For boards and management, this concentration of emissions in energy-related activities means that emissions exposure is often tied to an entity's core operations and supply chains, not a peripheral concern.

For governance purposes, the principal risks tend to be around accuracy, comparability, and consistency of disclosure rather than the underlying science. Whether and how an entity must measure or disclose GHG emissions depends on applicable law, sector, and entity type, and requirements vary considerably across jurisdictions and frameworks. Overstating reductions, using inconsistent boundaries, or presenting figures without clear methodology can create reputational, regulatory, and potentially legal exposure. This entry is educational and does not constitute legal, audit, or compliance advice.

Who it's relevant to

Boards and their committees
Boards, often through an audit, risk, or dedicated sustainability committee, typically hold oversight responsibility for whether the entity's emissions-related risks and disclosures are appropriately identified and governed. This is an oversight role rather than an operational one: the board generally challenges and monitors management's approach, including the choice of reporting boundary and framework, rather than compiling the underlying figures itself. Whether specific oversight duties apply depends on jurisdiction, sector, and entity type.
Management and sustainability or reporting functions
Management is generally accountable for the operational activities that produce emissions and for measuring, calculating, and preparing emissions figures using a defined methodology and boundary. Because a single CO2eq figure can reflect materially different scopes, such as inclusion or exclusion of the land sector, management is responsible for documenting the boundary and framework applied so that reported numbers are consistent and comparable over time.
Compliance and legal functions
Compliance and legal teams typically assess whether and how the entity is required to measure or disclose GHG emissions, since these obligations vary by applicable law, listing rules, sector, and jurisdiction. They also help manage the risk that emissions claims are inaccurate, inconsistent, or misleading, which can carry regulatory and reputational consequences.
Internal audit and assurance providers
Internal audit and external assurance providers may evaluate the design and operating effectiveness of the controls over emissions data, for example, whether the stated reporting boundary is applied consistently and whether the methodology is properly documented. Their role is to provide assurance over the reliability of the reported figures, distinct from the management function that produces them.
Investors and other external stakeholders
Investors, lenders, and other stakeholders increasingly use emissions data to assess an entity's exposure and performance. For these users, the reporting boundary and framework are essential context, since figures prepared on different bases may not be directly comparable across entities or reporting periods.

Inside GHG Emissions

Scope 1 emissions
Direct greenhouse gas emissions from sources owned or controlled by the entity, such as combustion in owned facilities or vehicles. Widely used disclosure frameworks generally treat Scope 1 as the most directly attributable category, though the precise boundary depends on the consolidation approach the entity adopts.
Scope 2 emissions
Indirect emissions associated with purchased electricity, steam, heating, or cooling consumed by the entity. Reporting frameworks commonly permit more than one accounting method (for example, location-based and market-based), and the choice can materially affect reported figures.
Scope 3 emissions
Other indirect emissions occurring across an entity's value chain, both upstream and downstream, that are not owned or controlled by the entity. These are typically the most difficult to measure, often rely on estimates and third-party data, and their inclusion or exhaustiveness varies by framework and jurisdiction.
Organizational and operational boundaries
The rules an entity applies to decide which operations and emission sources fall within its inventory (for example, equity share or control approaches). Boundary decisions drive comparability and are generally required to be disclosed under recognized accounting protocols.
Measurement, estimation, and data quality
The methods, emission factors, and assumptions used to quantify emissions, including reliance on measured data versus estimates. Because much emissions data is estimated rather than metered, data quality, methodology, and disclosed limitations are central to reliability.
Governance and oversight of emissions reporting
The allocation of responsibility for emissions data: management typically owns preparation of the inventory and related controls, while the board or a designated committee generally exercises oversight of climate-related disclosure. Assurance functions may provide independent evaluation depending on the entity's arrangements.
Assurance and verification
Independent review of reported emissions, which may range from limited to reasonable assurance depending on scope and the standards applied. Whether assurance is voluntary or required depends on jurisdiction, sector, listing status, and applicable regulation.

Common questions

Answers to the questions practitioners most commonly ask about GHG Emissions.

Are Scope 1, 2, and 3 emissions all the same kind of measurement that a company controls directly?
No. These categories differ in both source and degree of control. Scope 1 generally refers to direct emissions from sources an entity owns or controls; Scope 2 typically covers indirect emissions from purchased energy such as electricity, steam, heating, or cooling; and Scope 3 generally captures other indirect emissions across the value chain, both upstream and downstream, which the entity does not directly control. Because Scope 3 depends heavily on third-party data and estimation, it is typically the least precise and most challenging category to quantify. Treating all three as equivalent, directly controlled figures misrepresents both the data quality and the accountability involved. The applicable methodology, boundaries, and required categories depend on the framework used and any jurisdiction-specific disclosure rules. This entry is educational and not legal, audit, or compliance advice.
Is greenhouse gas emissions reporting a universal legal requirement for all companies?
Not universally. Whether emissions disclosure is a binding legal requirement versus a voluntary standard depends on the jurisdiction, sector, entity size, and listing status. In some jurisdictions certain entities face mandatory disclosure obligations, while in others reporting is undertaken voluntarily against non-binding frameworks or in response to investor or stakeholder expectations. The scope of what must be reported, whether assurance is required, and which categories are covered also vary. Because requirements are evolving and differ significantly by location and entity type, organizations should confirm the specific obligations that apply to them. This entry does not state the provisions of any particular law and is not a substitute for professional advice.
Which function within an organization should own greenhouse gas emissions data collection and reporting?
Ownership is typically split across lines. Operational responsibility for gathering, calculating, and reporting emissions data generally sits with management and relevant first-line functions such as sustainability, operations, or finance teams, depending on how the entity is structured. Second-line risk and compliance functions may set methodology standards, monitor data quality, and assess related regulatory obligations, while internal audit or external assurance providers may test the design and operating effectiveness of the underlying controls. The board or a designated committee generally retains oversight rather than operational responsibility. Precise allocation depends on the entity's governance structure, size, and any applicable disclosure regime, and remains a matter for the organization's own judgment.
How should the board provide oversight of greenhouse gas emissions reporting without taking on management's role?
Board oversight typically focuses on whether management has established credible processes, controls, and governance around emissions data rather than on performing the calculations. In practice this often includes understanding the basis of preparation and boundaries used, satisfying itself that data quality and estimation limitations are understood, considering whether assurance is appropriate, and confirming that disclosures are consistent with applicable requirements and other reported information. The board or its relevant committee generally monitors emerging regulatory obligations and reputational and strategic risk exposure. Where the board lacks technical expertise, it may seek management explanation or independent input. The specific committee structure and depth of oversight depend on the entity and its risk profile.
What controls help support the reliability of greenhouse gas emissions data?
Controls generally address both the design and the operating effectiveness of the data process. Common considerations include clearly defined organizational and operational boundaries, documented calculation methodologies and emission factors, controls over source data completeness and accuracy, reconciliation and review procedures, version control over spreadsheets or systems, and documentation of estimates and assumptions, particularly where Scope 3 or estimated data is involved. Segregation between those preparing and those reviewing the data supports reliability. Whether external assurance is obtained, and at what level, depends on the applicable framework or regulatory requirement. Designing effective controls remains a fact-specific exercise informed by the entity's data sources and risk assessment; this entry does not prescribe a specific control set.
How can an organization address the estimation and data quality limitations inherent in Scope 3 reporting?
Because Scope 3 emissions generally rely on third-party and estimated data, organizations typically focus on transparency about methodology and limitations rather than false precision. Practical steps often include documenting the categories included and excluded and the rationale, disclosing the estimation methods and data sources used, distinguishing measured from estimated figures, and describing known uncertainties. Some entities prioritize the most material categories and improve data quality over time, and may engage suppliers to obtain more direct data. Consistency of methodology across reporting periods, with clear disclosure of any restatements, supports comparability. The appropriate approach depends on the applicable framework, data availability, and the entity's own materiality judgments, and this guidance is educational rather than definitive.

Common misconceptions

Greenhouse gas emissions disclosure is a single, universally mandatory legal requirement.
Whether emissions reporting is legally required, and the scope of what must be reported, varies by jurisdiction, sector, entity type, and listing status. Some regimes impose binding requirements while others rely on voluntary frameworks or best-practice guidance; the two should not be conflated.
The board is responsible for measuring and preparing the entity's emissions inventory.
Preparing the inventory, applying methodologies, and operating the related controls are generally management responsibilities. The board or a relevant committee typically holds an oversight role rather than an operational one, and attributing the operational duty to the board is inaccurate absent specific qualification.
Reported emissions figures are precise and directly comparable across entities.
Emissions data, particularly Scope 3, often depends on estimates, emission factors, and boundary and methodology choices. Different accounting methods and boundaries can produce materially different figures, so comparability requires attention to the disclosed assumptions and limitations.

Best practices

Clearly define and disclose organizational and operational boundaries, and document the consolidation approach used so that reported figures are transparent and comparable over time.
Distinguish Scope 1, Scope 2, and Scope 3 in reporting, and disclose the methods, emission factors, and assumptions applied, including where figures rely on estimates rather than measured data.
Separate the roles of management and the board: assign preparation and control of the emissions inventory to management while ensuring the board or a designated committee maintains oversight of climate-related disclosure.
Confirm which requirements are binding for the entity given its jurisdiction, sector, and listing status, and treat voluntary frameworks as guidance rather than assuming universal applicability.
Consider engaging an independent assurance or verification function, and be explicit about the level of assurance obtained and the standards applied.
Document data quality limitations and known uncertainties, and treat these entries and disclosures as educational rather than as a substitute for legal, audit, or compliance advice tailored to the entity's facts.