Part 2: From voluntary to compliance: the new reality of GHG inventories

Executive summary 

• Reporting is shifting from a voluntary measure to a compliance requirement in key jurisdictions worldwide 
• Disclosures must align with the GHG Protocol and be accurate, auditable, and assurance-ready 
• Requirements include standardized methodologies, robust governance, and consistent documentation 
• Inventories reveal hotspots, enable science-based targets, and guide capital allocation and supplier engagement 
• Acting now reduces restatements/regulatory risk, prepares systems, and spreads cost and effort 
• Trio helps build structure, apply the right methods and factors, and deliver credible, comparable disclosures 

For many sustainability teams, GHG inventory preparation feels different this year — and with good reason. What used to be primarily a voluntary exercise to support goal setting and storytelling is rapidly becoming a regulated, reviewable disclosure tied to compliance obligations. 

Yet, as discussed in Part 1 of this guide, this shift can turn inventories into a strategic asset. As sustainability reporting has become more structured and regulated, companies have to adapt to more defined terms, governing bodies, and expectations for credibility. Clearer rules and common definitions strengthen investor trust and enable smarter decisions. Creating a credible and comparable annual emissions inventory is a foundational step to clearly communicating strategic climate actions required by emerging regulations and expected by key stakeholders. 

This second installment of this Trio guide explains what to do about these changes. It highlights risks, outlines the practices required under streamlined rules, and gives business leaders a practical path to convert voluntary reporting into credible disclosures that stand up to review and create value for your organization. 

Regulations are raising the stakes 

As global sustainability disclosure regulation continues to emerge, several key regulations are driving GHG emission reporting in the U.S. and Europe. These regulations require companies to produce accurate, auditable emissions disclosures that align with the GHG Protocol. 

• The EU’s Corporate Sustainability Reporting Directive (CSRD) has undergone major updates, narrowing its scope to the largest companies, with more than 1,000 employees and €450M+ in annual turnover, including qualifying non-EU companies with substantial operations in the EU. These firms must report under the European Sustainability Reporting Standards (ESRS) and obtain limited assurance, with updated standards due by 2027.  
• SB 253, California’s Climate Corporate Data Accountability Act, requires large companies with over $1B in annual revenue that do business in the state to report scopes 1, 2, and 3 emissions in alignment with the GHG Protocol. Scope 1 and 2 reporting begins in 2026, with scope 3 following in 2027. Limited assurance will be required starting in 2027, reinforcing that emissions data must be accurate, well documented, and audited by a third party.  
• On February 10, the New York State Senate passed S9072A, legislation that would establish the Climate Corporate Data Accountability Act (CCDAA) and require certain large companies doing business in New York to publicly disclose greenhouse gas emissions. The bill, which closely mirrors SB 253, must now be considered by the New York Assembly in the coming weeks, but is widely expected to advance early this legislative session.  

As reporting becomes a compliance obligation under these frameworks, a practical question emerges for business leaders: “Is our inventory credible and aligned with regulatory requirements?” 

Seizing the opportunity  

Stakeholders, from legal teams to executives and investors, are looking more closely at emissions data, how it’s sourced, and whether it aligns with the GHG Protocol’s core principles. This heightened attention is elevating rigor across organizations, encouraging standardized methodologies, robust documentation, and governance, all of which make inventories more comparable, credible, and assurance-ready.  

Developing an inventory is also the first step in building a broader climate strategy. A robust inventory translates emissions hotspots into a decarbonization roadmap, underpins science-based targets, informs capital allocation, and focuses supplier engagement. By quantifying risk and opportunity, it accelerates executive decision making and embeds climate considerations into planning, budgeting, and procurement, turning reporting into a strategic asset. 

The business case for strengthening your inventory  

For organizations approaching inventories for the first time — or for those seeking greater confidence in their disclosures — this moment presents an opportunity and business case to strengthen disclosure. With expert support, teams can establish consistent, standardized approaches using the best-available data, and build durable documentation and governance.  

Conducting GHG inventories with inconsistent approaches can result in errors or incompleteness. Ensuring there is formal governance, a standardized methodology, and consistent documentation will not only improve the precision of your emissions data but will also ensure the calculation and reporting process is credible and consistent.  

Bringing in an expert partner like Trio can help your organization navigate the regulatory burden, offering structure, establishing clear governance, and ensuring the appropriate methodologies and emission factors are being used. Third-party support helps internal teams move faster and with greater confidence.  

Trio can help you create an assurance-ready inventory and set the foundation for regulatory alignment. 

Preparing your annual GHG inventory can help identify gaps early and prepare internal systems for upcoming compliance cycles. Early movers will be in a stronger position once third-party assurance becomes mandated, avoiding the scramble that often comes when new regulations take effect. Taking a proactive approach also lowers the risk of restatements and regulatory findings, signals maturity to investors and customers, and spreads effort and cost across business cycles, avoiding last-minute premiums when assurance becomes mandatory.  

The bottom line 

GHG inventory season is entering a new era. As regulations shift emissions reporting from voluntary to compliance grade, the expectations for data management, documentation, and credibility are rising quickly.  

Internal teams shouldn’t carry this risk alone. With the right structures and support, organizations can build inventories that are truly assurance ready: credible, well governed, and aligned with emerging regulatory requirements. 

Trio can help prepare your audit-ready GHG inventory this year. Our experts have prepared 100+ inventories across six continents and will help your organization meet regulatory disclosure requirements with credibility and confidence. 

Next steps:  

• Join our GHG Inventory Office Hours for a discussion on boundary setting, methodology, controls, and what “assurance-ready” looks like in practice.  
• Alternatively, share a few details or questions about your GHG inventory, and our team will follow up to provide initial guidance.  

Partner with Trio today to start converting emissions data into margin, resilience, and growth.