What ISSB actually asks for
IFRS S1 and IFRS S2 are the ISSB's two standards. S1 covers sustainability-related financial disclosures in general; S2 is specific to climate. Both are written for investors, which is the detail that changes how you approach them — the question is not what you did for the environment, it is what climate does to your cash flows, access to finance and cost of capital.
S2 requires disclosure across four pillars inherited from the TCFD: governance, strategy, risk management, and metrics and targets. If you have reported under TCFD, the structure will be familiar. What is new is the rigour — S2 expects industry-specific metrics and, where you have set climate targets, the information a reader needs to judge whether they are credible.
Adoption is national, not automatic
The ISSB publishes the standards; it does not mandate them. Each jurisdiction decides whether to adopt, adapt or ignore them, and on what timetable. That means the first question is not “what does S2 say” but “which regulator applies to us, and what have they actually required”. Groups operating across borders frequently find they are subject to more than one regime with different effective dates.
In India, listed-entity sustainability reporting runs through SEBI's BRSR framework rather than through ISSB directly. Where a company also reports to investors abroad, both can apply at once, and the sensible response is to build one dataset that can serve both rather than two disclosure exercises.
Where first-time reporters lose time
Scope 3. S2 requires disclosure of Scope 3 greenhouse gas emissions, and for most companies the data does not exist yet in usable form. It sits with suppliers, in procurement systems that were never built to carry emissions factors, or nowhere at all. Reliefs for the first reporting period exist in several jurisdictions, but they postpone the problem rather than remove it.
The second is the connection between the sustainability report and the financial statements. S1 requires the two to be consistent and published at the same time. Where sustainability reporting has historically been run by a separate team on a separate calendar, that alignment is a process change, not a drafting exercise.
What to do before the cycle opens
Establish the reporting boundary and confirm it matches the consolidation basis used in the financial statements. Work out which Scope 3 categories are relevant and start the supplier engagement that will take longest. Document the governance — who reviews the numbers, who signs them off — because that is disclosed as well.
Assume the first year's numbers will be restated. Building the trail that lets you restate cleanly is more valuable than getting an estimate closer to the mark on the first attempt.
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