California’s Climate-Accountability Revolution: A Deep Dive into SB 253 and SB 261 Corporate GHG Reporting and Climate-Related Financial Risk Disclosure

California’s Climate-Accountability Revolution: A Deep Dive into SB 253 and SB 261 Corporate GHG Reporting and Climate-Related Financial Risk Disclosure

by  
Gavien Mok  
- 4 de septiembre de 2025

New Regulatory Era for Corporate Climate Disclosures

California has become the first U.S. state to mandate comprehensive corporate greenhouse gas (GHG) disclosures and climate-related financial risk reporting across a broad swath of the private sector. The California Climate Accountability Package, anchored by Senate Bills 253 and 261 and supported by SB 219, lays the foundation for a climate transparency regime that will affect thousands of large businesses operating in the world’s fifth-largest economy [1][2][3].

This landmark legislative initiative arrives amid growing pressure from regulators, investors, and civil society for companies to disclose and manage climate-related risks. Modeled in part on global frameworks such as the Grupo de trabajo sobre divulgación de información financiera relacionada con el clima (TCFD) y el Protocolo GEI, California’s approach signals a shift from voluntary to mandatory climate accountability [4].

Understanding SB 253 and SB 261

SB 253 (Climate Corporate Data Accountability Act) y SB 261 (Climate-Related Financial Risk Act) each target distinct but complementary aspects of climate disclosure:

  • SB 253 requires public and private companies with total annual revenues over $1 billion and doing business in California to report Scope 1, 2, and 3 GHG emissions.
  • SB 261 mandates companies with annual revenues exceeding $500 million to prepare biennial reports detailing riesgos financieros relacionados con el clima and measures taken to mitigate them [1][2].

Together, these bills represent a holistic approach to climate transparency, quantifying emissions on the one hand and mapping out risk exposure on the other.

Timeline and Compliance Requirements

The California Air Resources Board (CARB) is tasked with implementation. Key compliance milestones are as follows:

Requirement Type SB 253 SB 261
Company Revenue Threshold > $1 billion > $500 million
First Report Due 2026 (Scope 1 and 2) 2026 (first risk report)
Scope 3 Reporting Deadline 2027 No aplicable
Verification Requirement Third-party assurance (phased) No third-party assurance
Reporting Frequency Annually Biennially
Public Disclosure Platform Yes (CARB) Yes (CARB or company website)

[4][5]

SB 253: Mandatory GHG Emissions Disclosure

SB 253 establishes mandatory, public, and standardized disclosure of corporate GHG emissions, including:

  • Ámbito 1: Direct emissions from owned/controlled sources.
  • Ámbito 2: Indirect emissions from purchased electricity.
  • Ámbito 3: All other indirect emissions in the value chain (e.g., supply chain, product use) [1][4].

The legislation explicitly adopts the Protocolo GEI as the methodological framework and requires companies to obtain third-party assurance of their disclosures. Assurance for Scope 1 and 2 begins in 2026, and for Scope 3 by 2030, with CARB defining the technical parameters [5].

The inclusion of Emisiones de alcance 3 is particularly notable. Often comprising over 70% of a company’s total emissions footprint, Scope 3 has historically been excluded from mandatory U.S. disclosures due to measurement complexity. California’s move aligns with global best practices.

SB 261: Climate Financial Risk Transparency

SB 261 shifts the lens to climate risk. It compels companies to publish a biennial report identifying:

  • Material climate-related financial risks (both physical and transition-related).
  • Strategies and measures adopted to mitigate such risks.

The bill requires alignment with TCFD guidelines, though it does not impose a mandatory format. It emphasizes forward-looking risk management over backward-looking emissions inventory [2][6].

Companies may leverage existing climate reports for compliance, provided they cover all required elements and are made publicly accessible. Unlike SB 253, SB 261 does not require third-party verification, a deliberate decision to reduce compliance burdens while promoting transparency.

Strategic Implications for Corporates

Compliance with SB 253 and SB 261 will demand significant operational and governance shifts, especially in value chain data collection and climate risk governance. Strategic considerations include:

  • Data Infrastructure: Companies must invest in emissions tracking and climate scenario modelling tools.
  • Supply Chain Engagement: Particularly for Scope 3, firms will need to coordinate with suppliers and distributors.
  • Governance Alignment: Risk oversight will need to shift from ESG teams to enterprise-wide risk management functions.
  • Investor Communication: These disclosures will likely influence investor assessments and financing terms.

California vs. Global Standards: A Comparative Lens

Element California (SB 253 / SB 261) CSRD (EU) SEC Proposed Rule (U.S.)
Scope 3 Mandatory? Yes (SB 253, phased) Yes Partially (if material)
Risk Disclosure Standard TCFD (SB 261) ESRS/TCFD under CSRD TCFD
Third-Party Assurance Yes (SB 253) Yes (phased) Yes (limited, phased)
Applies to Private Companies Yes Yes No

[1][2][4][5][6]

California’s framework echoes many CSRD and SEC elements but goes further in its applicability to private firms and its strict Scope 3 timeline. It sets a national precedent, likely accelerating federal and state-level adoption.

Emerging Challenges and Criticisms

Despite strong momentum, implementation challenges persist:

  • Calidad y disponibilidad de los datos: Particularly for Scope 3, data gaps and inconsistent reporting standards could hinder comparability.
  • Compliance Costs: Smaller firms may struggle to absorb compliance-related expenses.
  • Legal Risks: California’s laws may face judicial challenges around extraterritoriality or federal pre-emption.

Still, the regulatory direction is clear: climate transparency is no longer optional.

Recommendations for Companies

To prepare effectively, companies should:

  1. Map GHG Inventory: Begin with a full Scope 1-2-3 inventory under the GHG Protocol.
  2. Develop a Risk Assessment Framework: Align with TCFD to identify and disclose physical and transition risks.
  3. Involucrar a las partes interesadas: Work with suppliers, investors, and internal teams to align expectations.
  4. Establish Internal Controls: Prepare for assurance by integrating climate metrics into existing financial controls.
  5. Stay Current: Monitor CARB guidance and stakeholder consultations [5][6][7].

For companies already pursuing forward-looking emissions strategies such as avoided emissions, these regulations provide a baseline from which to build broader impact narratives.

Reflexiones finales

California’s SB 253 and SB 261 reflect a transformative step in the maturation of climate-related corporate governance. By uniting emissions transparency with financial risk disclosure, the state is signalling a broader shift toward integrated, mandatory ESG reporting. For businesses, the message is clear: align now, or risk being left behind.

Referencias

[1] https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202320240SB253
[2] https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202320240SB261
[3] https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=202320240SB219
[4] https://ww2.arb.ca.gov/our-work/programs/california-corporate-greenhouse-gas-ghg-reporting-and-climate-related-financial
[5] https://ww2.arb.ca.gov/sites/default/files/2025-08/SB%20253%20261%20workshop%20slides%208-21.pdf
[6] https://www.insideenergyandenvironment.com/2025/05/key-takeaways-from-california-air-resources-boards-public-workshop-on-implementing-california-climate-disclosure-laws-sb-253-and-sb-261/
[7] https://corpgov.law.harvard.edu/2025/07/15/california-climate-accountability-getting-started-on-sb-253-and-sb-261-reporting/

Comienza a usar la Herramienta ESG de Seneca hoy

Monitorea el desempeño ESG en carteras, crea tus propios marcos ESG y toma decisiones empresariales mejor informadas.

Toolkit

Seneca ESG

¿Interesado? Contáctanos ahora

Para contactarnos, por favor llena el formulario a la derecha o envíanos un correo directamente a la dirección de abajo

sales@senecaesg.com

Oficina de Singapur

7 Straits View, Marina One East Tower, #05-01, Singapur 018936

+65 6223 8888

Oficina de Ámsterdam

Gustav Mahlerplein 2 Ámsterdam, Países Bajos 1082 MA

(+31) 6 4817 3634

Oficina de Taipéi

77 Dunhua South Road, 7F Sección 2, Distrito Da'an, Taipéi, Taiwán 106414

(+886) 02 2706 2108

Oficina de Hanói

Viet Tower 1, Thai Ha, Dong Da Hanói, Vietnam 100000

(+84) 936 075 490

Oficina de Lima

Av Jorge Basadre Grohmann 607 San Isidro, Lima, Perú 15073

(+51) 951 722 377

Oficina de Tokio

1-4-20 Nishikicho, Tachikawa City, Tokyo 190-0022