Greenhouse Gas

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On May 29, 2025, the California Air Resources Board (CARB) held a virtual public workshop to review and discuss its rulemaking response to California Senate Bills (SBs) 253, 261, and 219, which require companies that “do business in California” and meet certain revenue thresholds to publicly disclose their greenhouse gas (GHG) emissions and material climate-related financial risks. Although CARB staff presented some “initial staff concepts” concerning CARB’s approach to implementing SBs 253 and 261, CARB asked more questions than it provided answers. The clear takeaway from the workshop was that CARB has a long way to go before it is ready to issue a formal notice of proposed rulemaking on SBs 253 or 261, and there is still an open question of whether CARB will issue guidance or regulations for SB 261, which is self-implementing.

Challenging a slew of state climate-related laws and programs, President Trump’s April 8, 2025 executive order (EO) set the stage for more legal fights between the federal government and states. In the new EO, “Protecting American Energy from State Overreach,” Trump took aim at state laws and programs that address greenhouse gas emissions (GHGs), climate change, environmental justice, and environmental, social, and governance (ESG). Some states have already indicated they will oppose the Trump administration’s efforts.

On December 16, 2024, the California Air Resources Board (CARB) requested public feedback to “help inform its work to implement” the Climate Corporate Data Accountability Act (SB 253) and the Climate-Related Financial Risk Act (SB 261) (see our summary of these 2023 laws here). The “information solicitation” was issued shortly after California State Senator Scott Wiener and Senator Henry Stern, who authored the bills, penned a letter to CARB expressing their frustration with CARB’s apparent lack of momentum in advance of a July 2025 statutory deadline to adopt regulations governing the greenhouse gas (GHG) and climate risk disclosures that large entities “doing business in California” must make beginning in 2026. CARB is accepting comments in response to the solicitation for 60 days, through February 14, 2025.

On December 5, 2024, the California Air Resources Board (CARB) issued an Enforcement Notice regarding the Climate Corporate Data Accountability Act (SB 253), which will require companies “doing business” in California to report their Scope 1, 2, and 3 greenhouse gas emissions (GHG), with reporting for 2025 Scope 1 and 2 emissions beginning in 2026 (see our previous discussion of the law’s requirements here).

The march toward mandated corporate disclosures for climate-related risks continues. Despite significant pushback and substantial legal challenges, state legislatures and regulators are continuing to advance laws and rules that will require disclosures of both greenhouse gas (GHG) emissions and climate risks.

California Senate Bill (SB) 219, signed into law…

The U.S. Securities and Exchange Commission (SEC) has issued its long-awaited climate reporting requirements, making it mandatory for the largest publicly traded companies in the U.S. to annually disclose both greenhouse gas (GHG) emissions and their material climate risks, with some requirements kicking in as early as 2025. On March 6, the SEC voted 3-2 along party lines to pass a pared down version of its March 2022 proposal, giving regulated companies the final word on the much-anticipated rule.

On October 7, 2023, California Governor Newsom signed two landmark bills into law, Senate Bill (SB) 253 and SB-261, imposing new requirements on large companies doing business in California to publicly report their annual greenhouse gas (GHG) emissions and climate-related risks. These laws apply to both publicly traded and privately held companies, exceeding the scope of the climate disclosure rule proposed by the U.S. Securities and Exchange Commission (SEC) in March 2022. Our professionals have prepared a more detailed summary here; some key highlights are included below.

EPA’s long-promised rules for reducing CO2 emissions from fossil fuel-fired power plants have now been published. In the proposal, EPA lays out “performance standards” for new natural gas-fired power plants and “emission guidelines” for states to use in developing standards for existing gas- and coal-fired power plants.

On January 9, the White House Council on Environmental Quality (CEQ) issued an Interim Guidance on Consideration of Greenhouse Gas (GHG) Emissions and Climate Change (Interim Guidance) “to assist Federal agencies in their consideration of the effects of GHG emissions and climate change when evaluating proposed major Federal actions in accordance with the National Environmental Policy Act (NEPA).”

Much ado is being made of recent amendments to the Clean Air Act (CAA) contained in the Biden administration’s budget reconciliation law passed in mid-August, commonly referred to as the Inflation Reduction Act (IRA). And with good reason, as the law includes the most significant changes to the CAA since 1990, and the new sections formally define greenhouse gases (GHGs) as an “air pollutant,” consistent with the Supreme Court’s 2007 decision in Massachusetts v. EPA.

However, the IRA amendments to the CAA do not in fact make significant substantive changes in law. Legally speaking, they can’t, given that the IRA is merely a reconciliation bill through which Congress may only assign funding. More to the point, none of the IRA amendments to the CAA address in any way the limitations the Supreme Court recently placed on EPA’s authority to adopt climate change regulation in West Virginia v. EPA, notwithstanding some characterizations to the contrary.