ISSB standards (IFRS S1 and S2) report what climate does to the company, for investors. GRI reports what the company does to the world, for everyone else. CSRD requires both views at once.
ISSB is the global baseline: more than 40 jurisdictions have adopted it or are taking steps to, including Australia, Japan, the UK, Singapore and Hong Kong. CSRD is EU law. GRI is voluntary but the most widely used.
After the 2026 Omnibus, CSRD covers EU companies with more than 1,000 employees and EUR 450 million turnover, and non-EU parents with EUR 450 million of EU turnover from financial year 2028.
GRI 102: Climate Change 2025 replaces the GRI 305 emissions disclosures from 1 January 2027 and adds transition plans and just transition.
All three require Scope 1, 2 and 3 emissions measured to the GHG Protocol. One inventory, with an audit trail, feeds every report.
A sustainability lead at a food group with an Australian listing, European sales and a CDP response due has three frameworks to reconcile before the year is out. The questions are the same every year: which ones are mandatory, what each one wants that the others do not, and how much of the work can be done once.
This comparison covers the three that come up most: the ISSB's IFRS S1 and S2, the EU's Corporate Sustainability Reporting Directive (CSRD) with its European Sustainability Reporting Standards (ESRS), and the GRI Standards. It concentrates on climate and emissions, which is the part we work on. Where a threshold or date depends on your jurisdiction, check it against the regulator's text.
| ISSB (IFRS S1 and S2) | CSRD (ESRS) | GRI Standards | |
|---|---|---|---|
| Set by | International Sustainability Standards Board, part of the IFRS Foundation | European Commission, drafted by EFRAG | Global Reporting Initiative, an independent standard setter |
| Audience | Investors and lenders | Investors, regulators, civil society | All stakeholders |
| Materiality | Financial: how sustainability affects the company | Double: financial and impact | Impact: how the company affects people and planet |
| Status | Adopted or being adopted in more than 40 jurisdictions; mandatory where a regulator says so | EU law, mandatory for companies in scope | Voluntary, unless a stock exchange or law references it |
| Climate content | IFRS S2: governance, strategy, risk management, metrics and targets; 86 disclosures plus sector items | ESRS E1: transition plan, climate risk, targets, energy, Scope 1, 2 and 3 | GRI 102 Climate Change (2025) and GRI 103 Energy (2025), effective 1 January 2027 |
| Emissions method | GHG Protocol Corporate Standard unless the jurisdiction says otherwise | GHG Protocol, with ESRS-specific rules | GHG Protocol or ISO 14064-1 |
| Assurance | Set by each jurisdiction; Australia phases to reasonable assurance | Limited assurance mandatory | Not required by GRI; recommended |
[In-text graphic to come: a two-axis map, financial materiality to impact materiality across, voluntary to mandatory down, with ISSB top-left, GRI bottom-right (voluntary, impact) and CSRD spanning both materiality types on the mandatory row.]
The ISSB issued its first two standards in June 2023. IFRS S1 sets the general requirements; IFRS S2 is the climate standard. Both are structured around the four TCFD pillars, governance, strategy, risk management, and metrics and targets, and both ask one question: how do sustainability-related risks and opportunities affect the company's prospects, cash flows and cost of capital? That is financial materiality, and it is what makes ISSB the investor's standard.
IFRS S2 requires Scope 1, 2 and 3 emissions measured to the GHG Protocol Corporate Standard unless the jurisdiction requires another method, plus climate scenario analysis, transition plans where they exist, and the financial effects of climate risk. It has 86 disclosure requirements and sector-specific additions drawn from the SASB standards.
Its reach is the point. The IFRS Foundation reported in April 2026 that more than 40 jurisdictions have adopted the standards or are taking steps to introduce them. Australia's AASB S2, Japan's SSBJ standards, the UK's SDS, Singapore's and Hong Kong's exchange rules, Malaysia's NSRF and Mexico's CUE are all built on IFRS S2. If you report in any of them, ISSB is not a choice. Our post on IFRS S2 as the global baseline has the country list.
CSRD is a directive, so it is law in every EU member state. Companies in scope report against the ESRS inside their management report and have the report assured. ESRS E1, the climate standard, asks for a transition plan, climate risks and opportunities, targets, energy consumption, and Scope 1, 2 and 3 emissions.
Two things set it apart. The first is double materiality: a company reports both how climate affects it (the ISSB view) and how it affects the climate (the GRI view), and documents the assessment that decided which topics are material. The second is mandatory limited assurance, with penalties for non-compliance.
The 2026 Omnibus narrowed the scope. CSRD now applies to EU companies and groups with more than 1,000 employees and net turnover above EUR 450 million. The first wave of large public-interest entities has reported since financial year 2024; everyone else above the thresholds reports on financial year 2027, published in 2028. Non-EU parents with EUR 450 million of EU turnover report from financial year 2028. The Commission also simplified the ESRS in 2026, cutting the number of datapoints by more than half. Our EU climate disclosure guide has the full scope and timeline.
ESRS and IFRS S2 were written to work together. The joint EFRAG and ISSB interoperability guidance (May 2024) maps the climate disclosures, so a company reporting under both can reuse most of the content. The extra work under CSRD is the impact side of the materiality assessment and the audit trail behind Scope 3.
GRI has been the most widely used sustainability reporting standard for two decades. It is voluntary, modular, and built around impact materiality: what the organisation does to the economy, environment and people, reported for every stakeholder rather than for investors alone. Many stock exchanges and national codes reference it, and ESRS was drafted with GRI so that the impact half of CSRD lines up with it.
The climate content is changing. GRI 102: Climate Change 2025 and GRI 103: Energy 2025 take effect for reports published on or after 1 January 2027, with early adoption allowed. GRI 102 replaces the greenhouse gas disclosures in GRI 305 (305-1 to 305-5) and the climate risk disclosure in GRI 201-2. It asks for a transition plan, Scope 1, 2 and 3 emissions to the GHG Protocol or ISO 14064-1, targets, and a new set of disclosures on a just transition for workers and communities. Companies that report GRI alongside ISSB will find the emissions figures identical and the narrative different.
The overlap is almost total. All three require Scope 1, 2 and 3 measured to the GHG Protocol (GRI also accepts ISO 14064-1). All three want the methodology, the boundary and the emission factor sources disclosed. The differences are at the edges: ESRS E1 asks for both location-based and market-based Scope 2 and for energy consumption by source; IFRS S2 asks for the emissions figures to carry the same weight of evidence as the financial statements they sit beside; GRI 102 asks for emissions from land use change and biogenic CO2 to be shown separately, which lines up with the GHG Protocol's Land Sector and Removals Standard.
That is why the inventory is the place to start. Sime's sustainability team reports to Bursa Malaysia under rules built on IFRS S1 and S2 and discloses beyond carbon. Rather than build a report at a time, it consolidated 24 emission factor databases into 4, standardised collection across 18 countries and around 600 sites, and scaled from about 3,000 data points to about 50,000 with the same team. Every framework then draws from the same numbers.
Related reading: IFRS S2: the end of the sustainability reporting alphabet soup · The EU's climate disclosure rules: what you need to know · Australia's climate disclosure rules · Climate reporting for IFRS S2 · How Sime scaled carbon, waste and water data 10x