Understanding Corporate Carbon Reporting

Corporate carbon reporting is the process by which companies measure and disclose the greenhouse gases (GHGs) they emit into the atmosphere. In the United States, it spans mandatory government programs like the EPA GHGRP and voluntary frameworks like the GHG Protocol. Understanding what the data means, and what it doesn't, is essential to interpreting emissions disclosures accurately.

What Is the EPA Greenhouse Gas Reporting Program?

The EPA Greenhouse Gas Reporting Program (GHGRP) was established under the Clean Air Act and began collecting data in 2010. It requires any US facility emitting 25,000 metric tons of CO2-equivalent (CO2e) or more per year to report their emissions annually to the EPA.

As of 2023, approximately 8,737 facilities across 41 industry types report under GHGRP. These facilities account for roughly 85–90% of total US greenhouse gas emissions from large stationary sources. The data is publicly accessible through EPA's FLIGHT tool, and PlainCarbon makes it searchable and comparable at the company level.

GHGRP reporting covers direct facility-level emissions - what comes out of smokestacks, process vents, and other direct sources. It does not capture supply chain emissions or emissions from products after sale (those are Scope 3, discussed below). The data reflects actual measured or calculated emissions from physical operations, making it one of the most reliable datasets for understanding industrial emissions in the US.

The Three Scopes of Emissions

The GHG Protocol Corporate Standard, developed by the World Resources Institute and WBCSD, is the backbone of corporate emissions accounting globally. It organizes emissions into three "scopes":

What Is CO2-Equivalent (CO2e)?

Not all greenhouse gases have the same warming effect. To make comparison possible, scientists use Global Warming Potential (GWP) - a measure of how much heat a gas traps relative to CO2 over a 100-year period. Emissions are then expressed in CO2-equivalent (CO2e) tons.

Key conversions using GWP100 values from the IPCC Fifth Assessment Report (AR5), which EPA uses:

How Companies Calculate Emissions

Facilities use two primary approaches to calculate emissions:

Direct Measurement: Continuous Emissions Monitoring Systems (CEMS) physically measure what comes out of a stack. This is the most accurate method and is required for large power plants and certain industrial facilities under EPA rules. CEMS data is reported in near-real-time and has high reliability.

Calculation Methods: For most industrial processes, emissions are calculated using activity data (fuel consumed, materials processed) multiplied by emissions factors. EPA publishes standardized emissions factors for most fuel types and industrial processes. The formula is: Emissions = Activity Data × Emissions Factor × GWP.

Mass Balance: Some processes use mass balance, tracking inputs and outputs to calculate what was converted to emissions. This is common in petroleum refining and chemical production.

Voluntary vs. Mandatory Reporting

In the US, mandatory reporting is limited to large facilities (EPA GHGRP threshold: 25,000 MT CO2e/year). Many companies, especially those with significant Scope 3 exposure, voluntarily disclose more comprehensive data through:

• •CDP (formerly Carbon Disclosure Project): Investor-driven disclosure platform where companies report Scope 1, 2, and 3 data. CDP data is often more complete than EPA GHGRP but self-reported.
• •Task Force on Climate-related Financial Disclosures (TCFD): Framework for reporting climate risks in financial filings. Major banks and investors require TCFD alignment.
• •Science Based Targets initiative (SBTi): Companies set emissions reduction targets aligned with climate science. SBTi targets require verifiable Scope 1-3 tracking.
• •Annual Sustainability/ESG Reports: Most S&P 500 companies publish standalone sustainability reports, though quality, completeness, and verification levels vary widely.

Limitations of Corporate Emissions Data

Understanding the limitations of emissions data is as important as understanding what it says:

GHGRP captures facilities, not companies. A company may operate dozens of facilities, some below the reporting threshold. PlainCarbon aggregates facility-level GHGRP data to the company level using EPA's parent company data, but smaller facilities may be missed. The data on PlainCarbon represents a lower bound of company-level emissions.

Scope 3 is not in GHGRP. The EPA program captures Scope 1 direct emissions. It does not include Scope 2 (purchased electricity) or Scope 3 (value chain) emissions. For many industries, retail, finance, technology, Scope 3 dominates total footprint.

Parent company attribution changes over time. Mergers, acquisitions, and divestitures mean a company's emissions profile can change dramatically independent of actual emissions performance. A company that sells a coal plant will show lower emissions, but the coal plant still emits.

Intensity vs. absolute emissions. Many companies report emissions intensity (per unit of revenue or production). A company can grow emissions in absolute terms while improving intensity. Absolute emissions matter for the climate; intensity metrics matter for efficiency.

The Regulatory Horizon

Corporate climate disclosure requirements are expanding rapidly. California's SB 253 (effective 2026) will require companies with >$1B revenue operating in California to disclose all three scopes. The SEC's proposed climate disclosure rule, currently subject to legal challenges, would require publicly traded companies to disclose material climate risks and Scope 1/2 emissions.

The EU's Corporate Sustainability Reporting Directive (CSRD), effective 2025 for large EU companies, will require detailed sustainability disclosures including GHG data, with third-party assurance. Large US multinationals operating in the EU are subject to CSRD.