Six CARB listening sessions show where California's SB 253 emissions rules may bend

CARB's problem is translation. The GHG Protocol is a voluntary framework, and the agency told participants that turning it into an enforceable regulatory program means certain voluntary elements may need to become mandatory to satisfy California's statute ^[6]. Industry's case for staying close to the protocol rested on cost: duplicative reporting systems, higher spending and weaker comparability with other regimes, according to the ISS-Corporate summary of the sessions by Sara Derian and Jessica Lobo ^{[5] [15]}. The summary does not say which voluntary elements CARB has in mind.

On method, the agency has already given ground. Its flexibility on internal processes, accounting methodologies and organisational boundaries comes with one condition, consistency with the GHG Protocol ^[7]. CARB paired it with an admission that primary data is limited today ^[8]. Those concessions govern how a company counts its emissions. The mandatory-elements caveat governs what a regulator needs in order to enforce the count ^[6].

Scope 3 drew frequent comment. Participants said full reporting is resource-intensive and often depends on data outside a company's direct control ^[10]. The five-category start in 2027 is CARB's attempt to answer that by beginning where methods and data are most mature ^[9]. Feedback also turned on materiality and on balancing decision-useful disclosure against implementation burden, and ISS-Corporate notes that priorities differed among stakeholder groups ^[11]. Investors, NGOs and other data users sat in the same sessions as reporting companies ^[2].

Recalculation is the least settled item ^[12]. A rule on restating historical inventories decided in this round will determine how much finished inventory work companies may have to reopen in later reporting years.

The trade-off for a reporting company this quarter is between folding SB 253 into its existing GHG Protocol process and paying for California-specific work before the rules require it. ISS-Corporate's view is that the degree of alignment could decide whether compliance fits inside current reporting or needs additional California disclosures ^[14]. Companies and industry groups asked CARB to lean on existing disclosures and frameworks wherever possible ^[13]. I'd expect the method flexibility to survive into the final rule, because CARB stated it repeatedly and tied it only to consistency with the protocol ^[7].

The sequencing follows from that. A company that builds on its protocol process now pays only for the California additions once CARB names them. One that builds a separate California system now pays for duplication if the list turns out short, and duplication is a cost participants cited directly ^[5].