PERI Greenhouse 100 Suppliers State Press Release For California Using 2023 Data

February 11, 2026

UMass Amherst Political Economy Research Institute Releases New Greenhouse 100 Suppliers Index Tracking Corporate Fossil Fuel Emissions

Rollback in EPA reporting requirements may end Greenhouse 100 Suppliers Index and access to vital public information

AMHERST, Mass. — Researchers at the University of Massachusetts Amherst’s Political Economy Research Institute (PERI) today published a new Greenhouse 100 Suppliers Index, ranking the largest corporate contributors to greenhouse gas emissions from fossil fuel supplies.

The index reports 2023 greenhouse gas emissions resulting from oil, natural gas and coal supplies using the latest—and possibly last—data available from the U.S. Environmental Protection Agency’s Greenhouse Gas Reporting Program. In September 2025, the agency announced its intention to end most of the program and suspend remaining reporting requirements until 2034.

“The Greenhouse 100 Suppliers Index informs consumers, shareholders, regulators, lawmakers and communities about corporate releases of climate-altering pollutants into our environment,” says Professor Michael Ash, co-director of PERI's Corporate Toxics Information Project. “The EPA’s decision to effectively end the Greenhouse Gas Reporting Program removes access to vital public information and leaves public and private decision-makers flying in the dark or relying on a patchwork of voluntary and potentially cherrypicked or greenwashed reports.”

The Greenhouse 100 Suppliers rankings represent the first comprehensive database of corporate responsibility for greenhouse gas emissions and potential liability for resulting climate damage.

"In making this information available, we are building on the historic achievements of the right-to-know movement," Ash adds. "Our goal is to engender public participation in environmental decision-making and to help residents translate the right to know into the right to clean air, clean water and a livable planet."

The rankings draw on EPA data for oil and natural gas suppliers, combined with coal supplier data from the U.S. Energy Information Administration and the Mine Safety and Health Administration, using methods detailed in a peer-reviewed journal article. Coal suppliers were exempt from Greenhouse Gas Reporting Program requirements.

The PERI indexes track corporate environmental and environmental justice performance across U.S.-based industrial activity using uniform, mandated and comparable data, expanding federal facility-level reporting to the company level.

The following is PERI's analysis for California.

Overall

Top 5 Supplier Companies in California

Top 10 Supplier Facilities in California

Top 10 facilities in California

Contacts:
Michael Ash, mash@umass.edu

Aaron Kupec, akupec@umass.edu