What are the IFRS Sustainability Disclosure Standards?

IFRS S2 is the ISSB's standard for climate-related disclosure, and it exists for a specific reason: investors no longer take a balance sheet at face value when climate risk is involved. They want evidence that a business can hold up under a warmer, more volatile set of conditions, and that's what S2, paired with the broader IFRS S1 framework for sustainability-related risks and opportunities, is designed to provide. Rather than a standalone sustainability exercise, both standards tie that evidence directly into the financial reporting companies already produce.

S2 in particular isn't starting from a blank page. It builds on TCFD (the Task Force on Climate-related Financial Disclosures), which had already become the de facto standard for climate reporting before the ISSB formalised it into IFRS S1 and S2 in 2023. Adoption since then has moved quickly: as of August 2026, 35 jurisdictions had taken up the standards on a mandatory or voluntary basis, with another 11 working toward it, according to the IFRS Foundation's own tracker, which is updated on a rolling basis. The UK sits among the more advanced adopters via its own UK SRS, while the US remains one of the larger holdouts; across most of those 35-plus markets, though, S1 and S2 reporting is simply becoming standard practice.

Part of the problem was simply fragmentation. Every jurisdiction, and often every company, defined and reported these risks differently, which made comparison close to impossible and left companies carrying a compliance burden with little payoff in investor trust.

The IFRS Foundation's 2020 consultation set out to test whether the market wanted something better, and the response left little doubt: investors, regulators and standard-setters alike wanted one reliable, comparable baseline. That consultation is what eventually produced the IFRS Sustainability Disclosure Standards.

The IFRS Foundation isn't new to setting global rules. It's long been behind international accounting standards, the shared framework that lets an investor anywhere trust a set of accounts prepared anywhere else, now required across more than 160 jurisdictions and treated as the default for how cross-border business gets reported.

That same discipline is now being extended to sustainability. The logic doesn't change: bring the same consistency and comparability that already exists for financial data to ESG information, so that a sustainability disclosure gets read with the same seriousness, and carries the same real financial weight, as anything on the balance sheet.

The body actually responsible for IFRS S1 and S2 is the ISSB, set up by the IFRS Foundation in 2021 as the sustainability counterpart to the International Accounting Standards Board (IASB). Where the IASB owns the traditional accounts, the ISSB owns the sustainability-related information now shaping how a company gets valued.

Its mandate is deliberately a floor, not a ceiling: a clear, comparable framework for how climate risk and social change feed into cash flow, resilience and long-term performance, that individual jurisdictions then build on rather than replace. The UK is a good example of how that plays out in practice, layering its own UK SRS on top of the ISSB baseline rather than inventing something separate (more on that below). Wherever a company is based, the underlying facts an investor is looking at stay the same; it's only the local wrapper around them that varies.

Applying both in practice means holding climate and sustainability disclosures to the same standard as the financial statements: governance, strategy, risk management, and metrics, sitting right alongside the numbers investors already use. You'll sometimes see the pair called the "IFRS ESG standards" instead, a slightly loose label, since the ISSB's own focus is specifically financial materiality rather than ESG in the broader sense, but the two terms get used interchangeably often enough to be worth knowing they're not strictly identical.

The standard requires companies to disclose the sustainability-related risks and opportunities that directly impact their ability to generate cash over the short, medium, and long term. Whether it’s a dependency on a scarce natural resource or a vulnerability in a global supply chain, these factors have a tangible effect on a company's cost of capital and its attractiveness to investors.

That doesn't mean disclosing everything, though. The standard is deliberately proportionate: if a piece of information couldn't reasonably sway an investor's decision, it doesn't belong in the report. That keeps the focus on what's financially material, rather than turning into an exhaustive ESG checklist.

The four pillars of disclosure

To ensure investors get a complete picture, both IFRS S1 and S2 are organised around four core pillars, the same four at the heart of TCFD, so the structure should already feel familiar to anyone who's reported under that framework before. These pillars aren't just a checklist; they describe how a business actually integrates sustainability into its DNA:

Defining material information

This is fundamentally about quality: the standard demands a complete, neutral, and accurate account of a company's position. In practice, that means applying the same level of rigour to sustainability data that has always been reserved for the balance sheet.

To make this transition easier, the reporting mechanics (how often you report, how you handle estimates, how you show year-over-year comparisons) are designed to mirror traditional financial statements. For companies already used to IFRS accounting, these requirements will feel familiar, allowing sustainability and financial data to sit naturally side-by-side.

While S1 provides the framework, IFRS S2 zooms in on the most pressing financial challenge of our time: climate change. It’s structured around the same four pillars we just covered, but it adds a sharp focus on the specific ways climate shift impacts a company’s outlook.

1. Identifying the impact: Risks and opportunities

Under S2, companies are expected to look at climate through two distinct lenses:

2. The disclosure requirements

To give investors a clear view of the future, S2 requires transparency across the business:

By 2026, the "first-look" period is over. For most organisations now in scope, S1 and S2 reporting sits inside the normal annual cycle, whether that's a deliberate strategic choice or simply what regulation now requires.

Are these IFRS sustainability disclosure standards mandatory?

The ISSB itself has no power to make anything compulsory; it sets the baseline, and it's down to national and regional regulators to decide whether to require it.

What's changed since launch is the pace: jurisdiction after jurisdiction has moved to adopt or align with the framework, and if anything that's only sped up. For companies, the mandatory question tends to come down to one of two routes:

There's more to adopting IFRS S1 and S2 than ticking a compliance box. A more disciplined approach to data is itself the benefit, and it's what gives companies a clear route to both regulatory stability and investor confidence.

From TCFD-era reporting through to full IFRS S1 and S2 disclosure, and everything these standards touch across a broader ESG programme, Greenly brings it all together on one platform: