As scrutiny around sustainability performance intensifies, many organizations face a critical question: when and how should we change our greenhouse gas (GHG) emissions baseline without risking transparency or accusations of greenwashing? Rebaselining is an essential but complex exercise that ensures your emissions reporting remains accurate and relevant as your organisation evolves.

In this post, we demystify the triggers for rebaselining, explain how to execute it successfully, and share best practices for communicating changes clearly and confidently.

What is Rebaselining?

Rebaselining means updating the reference point, or baseline, against which you measure your GHG emissions performance over time. This baseline forms the foundation for setting decarbonisation targets and tracking progress. However, as businesses change through growth, mergers, acquisitions, or data improvements, the original baseline can become outdated and no longer reflect your current emissions accurately. Rebaselining adjusts this baseline so your reporting remains relevant and credible.

Common Triggers for Rebaselining

Several situations typically indicate it’s time to rebaseline:

• Organisational changes: Mergers, acquisitions, divestments, or major restructuring can change your emissions footprint significantly.
• Boundary changes: Adding or removing operational sites, facilities, or subsidiaries affects what emissions you include.
• Data quality improvements: Discovering errors or accessing more accurate, complete data can significantly alter your reported emissions.
• Methodology updates: Changes in emissions factors, calculation methods, or regulatory frameworks may require updating your baseline.
• Mandatory requirements: Some reporting standards or investor frameworks, like the Science Based Targets initiative (SBTi), require rebaselining at set intervals or after major events.

Risks and Challenges of Rebaselining

Rebaselining is not without risks. Frequent or unjustified baseline changes can cause confusion and damage stakeholder trust, potentially leading to accusations of greenwashing. Poor documentation, lack of stakeholder involvement, and rushed processes are common pitfalls that can undermine the credibility of your emissions reporting. Therefore, it’s critical to approach rebaselining with a structured policy and governance framework.

Steps for a Successful Rebaselining Exercise

Define clear policies

Establish internal guidelines specifying when rebaselining is appropriate, and assign responsibility to manage the process.

Collect accurate data

Gather updated operational and emissions data that reflect any organizational or methodology changes.

Implement rigorous version control

Maintain detailed audit trails documenting what changed, who changed it, and why.

Recalculate and validate

Use the updated data and methodologies to recalculate your baseline, then conduct internal reviews with stakeholders across relevant departments.

Obtain formal approval

Finalise the new baseline with sign-off from designated decision-makers.

Communicate transparently

Clearly explain changes, their reasons, and impacts in your sustainability reports and to internal and external stakeholders.

Communicating Rebaselining Effectively

Transparent communication is essential to maintain trust and avoid confusion.

Internally, keep teams, including leadership, finance, sustainability, procurement, and operations, informed from the outset with regular updates and tailored training.

Externally, disclose rebaselining clearly in all GHG reports, outlining the rationale, data adjustments, and impacts on your emissions trajectory and reduction targets. Proactively engage key stakeholders to manage expectations and invite feedback, reinforcing your commitment to credible sustainability practices.

Technology as a Key Enabler

Many challenges in rebaselining arise from manual data handling and insufficient version control. Leveraging a dedicated carbon accounting platform, such as Climatise, can automate data collection, recalculation, and audit trail management, reducing errors and administrative burden. This allows your team to focus on analysis, stakeholder engagement, and communication, critical activities for successful rebaselining.

Rebaselining Readiness Checklist

To prepare your organisation in the best possible way, follow these steps:

• Assess your current baseline and its limitations.
• Identify triggers such as organisational shifts or methodology updates.
• Develop clear policies and assign ownership.
• Organise and collect updated, traceable data.
• Implement version control with adequate audit trails.
• Plan internal and external stakeholder communication.
• Pilot the process on a smaller footprint to iron out issues before full rollout.

Conclusion

Rebaselining is a necessary and responsible practice to ensure your GHG emissions reporting remains accurate and trustworthy amid organisational changes and evolving data. While it requires careful planning and transparent communication, a structured approach supported by technology can help you navigate the process confidently and maintain stakeholder trust. By anticipating rebaselining needs and building strong foundational policies now, your organisation will be well-positioned for credible, effective sustainability reporting.

If your company is approaching a rebaselining exercise, investing time in strong governance, clear communication strategies, and the right tools will make the process smoother and strengthen your sustainability leadership.