The International Sustainability Standards Board (ISSB) was established by the IFRS Foundation in 2021 and published its first two standards — IFRS S1 (general sustainability disclosures) and IFRS S2 (climate-related disclosures) — in June 2023. As of 2026, ISSB is the closest thing to a global baseline for sustainability reporting that the world has ever had. It matters because investors finally have a comparable disclosure across jurisdictions.
The four pillars (from TCFD, preserved in ISSB)
- Governance: how the board and management oversee climate-related risks and opportunities.
- Strategy: how climate risks affect the business, strategy, and financial planning over short, medium, and long term.
- Risk management: the processes for identifying, assessing, and managing climate-related risks.
- Metrics and targets: emissions disclosures, climate-related targets, and performance against them.
Why TCFD became ISSB
The Task Force on Climate-Related Financial Disclosures (TCFD), set up by the FSB in 2015, did the hard intellectual work of designing the four-pillar disclosure framework. In 2023, TCFD was formally retired and its work absorbed into ISSB. If a company says it 'reports against TCFD', it now reports against IFRS S2 — same framework, new name.
The current jurisdictional stack
ISSB is the global baseline; most major jurisdictions are layering rules on top.
- EU CSRD (Corporate Sustainability Reporting Directive): mandatory for ~50,000 EU and EU-active companies. Double materiality. Audited. Broader than just climate — includes social, biodiversity, governance.
- UK SDR + TCFD-aligned: TCFD-aligned reporting mandatory for large UK companies since 2022; transitioning to ISSB-aligned via UK Sustainability Disclosure Standards (UK SDS).
- US SEC climate rule: finalised 2024, requires Scope 1 and Scope 2 disclosure for large issuers, climate-risk strategy and governance. Scope 3 dropped from final rule. Currently subject to legal challenge.
- Kenya, Nigeria, South Africa, Brazil, Japan, Singapore: ISSB-aligned national standards in adoption phase as of 2026.
What a credible disclosure looks like
A box-ticked disclosure restates the four pillars and reports a Scope 1 number. A credible disclosure does more:
- Scope 3 is reported with methodology and data quality disclosed (most material for most companies, hardest to get right).
- Scenario analysis includes at least one 1.5°C-aligned scenario and one delayed-transition scenario.
- Financial impacts of climate risk are quantified — even if the quantification has wide uncertainty bands.
- Transition plan includes specific, time-bound capex and operational commitments, not aspirational language.
- Governance section names the board committee responsible and the frequency of climate discussions.
Audit is coming
ISSB and CSRD both require limited assurance on sustainability disclosures by 2026-2028, moving to reasonable assurance (the level required for financial statements) by 2030-2032. This is the change that makes box-ticked disclosures untenable — auditors will refuse to sign off on numbers that have no methodological basis.
Exercise
Pull the most recent IFRS S2 (or TCFD-aligned) disclosure from a listed company. Check it against the credibility checklist above. Which items are present and credible? Which are absent or boilerplate? What would a sophisticated investor flag as the weakest section?