Global reporting teams increasingly face both ISSB-aligned sustainability disclosure and CSRD/ESRS reporting. The frameworks are not identical, but they can be supported by a shared evidence model.
ISSB focuses on sustainability-related financial disclosure for capital markets. IFRS S1 covers general sustainability-related financial information. IFRS S2 focuses on climate-related disclosures. The lens is investor-oriented and financially material.
CSRD and ESRS are broader. They include double materiality, meaning companies assess both financial effects and the organization’s impacts on people and the environment. ESRS can require detailed topic disclosures beyond climate, depending on materiality.
The practical overlap is significant:
- Governance of sustainability risks and opportunities.
- Strategy and business model implications.
- Risk-management processes.
- Metrics and targets.
- Climate data and greenhouse gas emissions.
- Controls, sign-off, and assurance evidence.
The differences matter most in materiality, breadth, and granularity. A team cannot assume ISSB reporting automatically satisfies CSRD. But it should not build two disconnected reporting systems either.
Hydrus supports a shared source-of-evidence approach. Emissions data, activity data, factor sources, methodology, owners, approvals, and audit trail can support multiple disclosure outputs. Framework mapping determines which evidence feeds ISSB, CSRD, GRI, CDP, or other reporting.
For global companies, the operating model should be: one governed sustainability data layer, one methodology record, one evidence trail, multiple disclosure outputs.
The mistake is to start from report templates. Start from data, lineage, and controls. Then generate the disclosures required by each framework.
This guide is educational and not legal or assurance advice.