From TCFD to IFRS S2: What Actually Changes in Your Climate Disclosure

It is early March 2026. A head of sustainability reporting at a FTSE 250 company is sitting at her desk with last year's TCFD report open on one screen and a letter from her external auditor on the other. The letter is polite. It lists nine items her report does not yet cover. Some she expected. Some she did not. All of them map to specific paragraphs of IFRS S2.

Her company has been doing TCFD for four years. The governance disclosures are mature. The risk pillar is well understood. She knows the four-pillar shape of a climate disclosure better than most people know their own address. And yet the letter still runs to two pages.

This is the part of the IFRS S2 transition that no one prepared her for. The standard is not a fresh framework. It is TCFD, adopted into the IFRS Foundation in 2024, and then tightened in nine specific places. If you already file TCFD, your migration is not a blank page. It is a checklist of nine changes.

Let me walk you through each of them. Every section below names the exact paragraph in IFRS S2, tells you what TCFD asked for in the same area, and describes what the auditor will now look for.

The nine changes, at a glance

Every row below gets its own section. If you are short on time, the table is the migration. Read it, mark the three items that give you the least confidence, and start there.

Change 1: Scope 3 stopped being optional

TCFD asked you to "describe Scope 1, Scope 2, and, if appropriate, Scope 3 greenhouse gas emissions." That "if appropriate" did a lot of work. Most TCFD reports disclosed Scope 1 and 2 and wrote a paragraph explaining why a full Scope 3 inventory was not yet practicable.

IFRS S2 paragraph 29(a)(i) through (iii) removes that latitude. You must disclose absolute gross Scope 1, Scope 2, and Scope 3 emissions, measured in accordance with the GHG Protocol Corporate Standard, unless the jurisdiction in which you report requires a different method. For Scope 2, you must also disclose a location-based figure and give information about any contractual instruments you relied on. For Scope 3, you must disclose the fifteen categories as relevant, and if you are an asset manager, bank, or insurer, category 15 (financed emissions) is not optional.

There is a one year transition relief: in the first annual reporting period in which you apply IFRS S2, you may defer Scope 3 disclosure by twelve months. That relief runs out fast. Most first-time appliers will use it, then spend that year building a defensible Scope 3 inventory from screening to targeted primary data for the categories that matter most.

Change 2: Seven prescribed cross-industry metrics

TCFD recommended four cross-industry metrics: GHG emissions, transition risks, physical risks, and climate-related opportunities. Most reports disclosed the first and wrote a paragraph on the others.

IFRS S2 paragraph 29 mandates seven, and the additions are the expensive ones:

1. Absolute gross Scope 1, 2 and 3 emissions.
2. The amount and percentage of assets or business activities vulnerable to transition risks.
3. The amount and percentage of assets or business activities vulnerable to physical risks.
4. The amount and percentage of assets or business activities aligned with climate-related opportunities.
5. The amount of capital expenditure, financing, or investment deployed toward climate-related risks and opportunities.
6. An explanation of whether and how climate-related considerations are factored into executive remuneration.
7. The price for each metric tonne of greenhouse gas emissions used internally, including how it is applied in decision-making.

Items 2, 3, 4, 5 and 7 typically break existing reports. Item 6 breaks the remuneration committee's calendar. Plan for cross-functional work with finance, treasury, HR, and investor relations. This cannot be authored inside the sustainability team alone.

Change 3: Industry-based metrics are required, and they come from SASB

TCFD published supplemental sector guidance for four financial industries and non-financial groups. It was useful, but non-binding and incomplete.

IFRS S2 paragraph 32 requires you to consider the industry-based disclosure topics and metrics set out in the accompanying Industry-Based Guidance, which was built by porting the SASB standards into the ISSB framework. Appendix B of S2 references the full set. You must disclose the industry metrics that are applicable to your business model and that meet the materiality threshold in IFRS S1.

In practice: find your SASB Sustainable Industry Classification System code, pull the corresponding industry standard, and work through the topics one by one. Some will be clearly applicable. Some will be clearly not. Some will require judgement. All of that judgement becomes disclosable.

Change 4: Financial effects must be quantified where possible

TCFD asked you to "describe the impact of climate-related risks and opportunities on the organization's businesses, strategy, and financial planning." Most reports described this in general terms.

IFRS S2 paragraphs 15 to 21 raise the bar. You must disclose the current financial effects of climate-related risks and opportunities on your financial position, financial performance, and cash flows. You must also disclose the anticipated financial effects over the short, medium, and long term. Quantitative disclosure is required, in single amounts or ranges, unless you cannot provide a quantitative disclosure without undue cost or effort. If you cannot, you must explain why and provide qualitative information instead.

This is the single biggest uplift for most reporters. It forces the sustainability function and the financial reporting function to share inputs, assumptions, and time horizons. If you disclose that transition risk is material to your refining business, but your impairment test in the financial statements uses assumptions inconsistent with that disclosure, an auditor will catch it. Paragraphs 21 and 22 require the two to reconcile.

Change 5: Scenario analysis is required, not recommended

TCFD recommended that organisations use scenario analysis, including a 2 degree Celsius or lower scenario. It was a recommendation. Many reports limited themselves to a narrative description.

IFRS S2 paragraph 22 states that you shall use climate-related scenario analysis to assess your climate resilience. You must disclose the scenarios used, the sources of those scenarios, the time horizons, the assumptions, and how your strategy and business model would respond. Proportionality applies: depth matches your circumstances and available information. But the analysis itself is mandatory, and the disclosure of how you did it is mandatory.

For first-time appliers, the common failure mode is using an off-the-shelf scenario (IEA Net Zero by 2050, NGFS Current Policies, one of the SSP pathways) without connecting the outputs to your own operational decisions. The auditor's question is always the same: what did you do differently because of the scenario output? If the answer is nothing, the scenario analysis is not yet functioning as a resilience test.

Change 6: The transition plan becomes an explicit disclosure

TCFD mentioned transition plans, but treated them as a sub-topic inside strategy. You could publish a strong climate strategy without ever using the phrase "transition plan".

IFRS S2 paragraph 14(a)(iv) is explicit. If the entity has a climate-related transition plan, it must disclose the plan and the information the entity used to set and review it. This includes the targets, the interim milestones, the key assumptions, the dependencies on external factors (policy, technology, supply), and how the plan fits with the jurisdictions in which the entity operates. If the entity does not have a plan, that fact itself has to be disclosed.

The practical implication: a transition plan is now a disclosable asset with the same evidentiary requirements as a financial forecast. Vague or aspirational plans become a risk, not a neutral placeholder.

Change 7: Location and timing become fixed

TCFD reports lived wherever the reporter chose. Sustainability report, annual report, standalone TCFD document, website. The timing could lag the financial statements by months.

IFRS S2 paragraphs 60 to 69 fix both. Climate disclosures must be part of the general purpose financial report. They must cover the same reporting period as the financial statements. They must be released at the same time as the financial statements. Cross-references to another document are permitted only where the information is available on the same terms and at the same time.

For most companies this means the sustainability reporting calendar now compresses into the financial close calendar. The last-minute sustainability data gathering that used to happen in the weeks after year-end no longer fits. Data has to be ready, controlled, and signed off on the same timeline as financial disclosures.

Change 8: Connected information with the financial statements

TCFD did not require any formal link between the climate report and the financial statements. Two documents, two teams, two sets of numbers.

IFRS S2 paragraphs 21 and 22 require the two to be connected. When you make a climate disclosure that relies on data or assumptions, you must use inputs that are reasonably consistent with the inputs used in the financial statements, and disclose the relationships. Useful asset lives, impairment indicators, fair value measurements, pension discount rates, expected credit losses: all of these can be affected by climate assumptions, and the two disclosures have to agree.

This is where the sustainability team stops working alone. The finance team, the controller, and the external auditor become stakeholders in every climate assumption that flows into a disclosure.

Change 9: The standard is drafted for assurance

TCFD reports were rarely audited at anything beyond a limited assurance opinion on selected metrics. IFRS S2 was built assuming audit from the start.

The standard itself does not impose assurance. But jurisdictions adopting it are layering assurance on top. The UK's expected phase-in, Australia's AASB S2 tiered rollout, Singapore's SGX rules, and the EU's parallel CSRD assurance requirements all point in the same direction: limited assurance first, reasonable assurance later.

The practical consequence is that every disclosure needs the supporting evidence an auditor expects. Data lineage. Method documentation. Internal controls. Version control on estimates. If your climate disclosures were authored in Excel with no documented methodology, that approach will not survive the first external review.

What doesn't change

The structural shape of your report largely carries over. The four pillars (governance, strategy, risk management, metrics and targets) are the same. The governance disclosures are close to TCFD's original recommendations. The risk management language is similar. The treatment of physical risks (acute and chronic) and transition risks (policy and legal, technology, market, reputation) uses the same taxonomy as TCFD.

The migration is scoped, not total. If you wrote a strong TCFD report, a large share of that text can be adapted. What you are adding is quantitative discipline, linkage to the financial statements, and a higher bar of evidence, not a new conceptual framework.

A practical migration roadmap

For a mid-sized listed company running a mature TCFD process, the nine changes typically sequence into an eight to twelve week plan.

Weeks 1 and 2: gap assessment. Take your most recent TCFD report and score it against each of the nine changes. The Greentryst IFRS S2 Gap Assessment walks through this in roughly twelve minutes and produces a readiness score per pillar.

Weeks 2 to 4: Scope 3 screening. Run a spend-based or activity-based screening across all fifteen categories. Identify the three to five categories that account for more than 80 per cent of your Scope 3 footprint. Build a data collection plan for those.

Weeks 4 to 8: quantification of financial effects. Pick one or two material risks and work through a quantified estimate for current and anticipated effects. This is not a one-shot exercise. The first estimate will be rough. The disclosure is about the methodology and the ranges, not a single number.

Weeks 6 to 9: scenario analysis uplift. Choose two contrasting scenarios (commonly a 1.5 degree pathway and a 3 degree pathway). Run them against your material risks. Document the assumptions. Capture the strategic decisions that changed as a result.

Weeks 9 to 12: assurance readiness. Build the evidence file. Document each metric's source, method, and internal controls. Walk your external auditor through it before year-end, not after.

Frequently asked questions

What is IFRS S2?

IFRS S2 is the ISSB's standard for climate-related disclosures, published in June 2023 by the International Sustainability Standards Board under the IFRS Foundation. It sits alongside IFRS S1, which covers general sustainability disclosures. Together, S1 and S2 form the global baseline for investor-focused sustainability reporting.

What does IFRS S2 stand for?

IFRS S2 stands for International Financial Reporting Standard S2 Climate-related Disclosures. The "S" series designates IFRS Sustainability Disclosure Standards, distinguishing them from the financial reporting standards that use the IFRS 1 through IFRS 18 numbering.

Is IFRS S2 mandatory?

The IFRS Foundation does not itself mandate the standard. Adoption happens jurisdiction by jurisdiction. The UK, Australia, Japan, Canada, Brazil, Singapore, Hong Kong, Nigeria, Malaysia, and Turkey have all announced adoption or adoption pathways, most with effective dates between 2025 and 2028. Whether S2 is mandatory for your entity depends on where you are listed and where you operate.

What is the difference between IFRS S2 and TCFD?

IFRS S2 inherits the TCFD four-pillar architecture, then tightens it in the nine areas described above. The biggest differences are mandatory Scope 3, seven prescribed cross-industry metrics, required industry-based metrics via SASB, quantified financial effects, required scenario analysis, explicit transition plan disclosure, fixed location and timing inside the general purpose financial report, connected information with the financial statements, and a design fit for external assurance. In June 2023 the Financial Stability Board confirmed that TCFD's disclosure work has been taken over by the ISSB.

Does IFRS S2 replace TCFD?

Operationally, yes. The TCFD task force was disbanded in 2023 and its monitoring work transferred to the IFRS Foundation. Companies still publishing "TCFD reports" are doing so under frameworks that reference TCFD recommendations, but all forward momentum sits with IFRS S1 and S2.

Is Scope 3 required under IFRS S2?

Yes, under paragraph 29(a)(iii). The standard provides a one year transition relief for first-time appliers, and financial sector entities must disclose category 15 (financed emissions). The measurement basis is the GHG Protocol Corporate Standard unless a jurisdiction specifies otherwise.

What is the IFRS S2 industry-based guidance?

It is a set of industry-specific disclosure topics and metrics built on the SASB standards, covering 68 industries across 11 sectors. Paragraph 32 of S2 requires entities to consider the applicable industry guidance when preparing their disclosures. The SASB Sustainable Industry Classification System (SICS) code determines which standard applies.

Is IFRS S2 the same as CSRD?

No. IFRS S2 is investor-focused and applies a financial materiality lens, consistent with IFRS S1. The EU's CSRD, through the ESRS standards, applies a double materiality lens and serves a broader stakeholder audience. The two frameworks overlap in subject matter but not in philosophy. Many companies subject to both will produce a single climate disclosure that satisfies the higher bar, with a mapping annex.

How do IFRS S1 and S2 relate to GRI?

The IFRS Foundation and the Global Reporting Initiative signed a collaboration agreement in 2022 to align definitions and concepts where possible. GRI remains multi-stakeholder and impact-focused, while IFRS S1 and S2 are investor-focused. Many companies report under both, using GRI for impact-oriented disclosures and ISSB for financial-materiality-oriented ones.

When does IFRS S2 apply to my company?

Check the adoption status in your primary listing jurisdiction and any other jurisdictions in which you have reporting obligations. The IFRS S2 Gap Assessment captures your jurisdiction and fiscal year start, then flags which effective date applies and what the expected phase-in looks like.

Where to go next

If you have an existing TCFD report and want to know how far it is from an S2-ready disclosure, start with the IFRS S2 Gap Assessment. The tool walks through each of the nine changes, scores your current readiness, and produces a pillar-by-pillar action list.

If you want to learn the standard end to end before you touch your own report, the IFRS S2 course covers all seven modules with paragraph-level source references and worked examples.

If you work in the financial sector and your priority is financed emissions, the course includes a dedicated module on category 15 disclosures for asset managers, banks, and insurers.

The migration is scoped and sequential. You do not have to redo four years of TCFD work. You have to add nine specific things to it. Work through them in the order above, and the first IFRS S2 report stops feeling like a rewrite and starts feeling like an upgrade.