By Vanguard with the work of Robert G. Eccles, George Serafeim, Jean Rogers, Baruch Lev, and Mary Schapiro.

Executive Summary

Sustainability reporting is moving from the margins of corporate communications into the operating center of accounting, finance, risk, and investor relations. In 2026, the issue is no longer whether companies should discuss environmental, social, and governance performance. The more important question is whether those disclosures can be measured, controlled, assured, and connected to financial outcomes.

This shift is redefining the accounting function. ESG reporting was once treated largely as a communications exercise, often managed by sustainability teams with support from legal, investor relations, and public affairs. That model is no longer sufficient. Investors, regulators, lenders, customers, and boards increasingly expect sustainability information to be decision-useful, comparable, timely, and reliable. Those are accounting concepts as much as sustainability concepts.

The challenge is that many ESG metrics were not originally designed for financial reporting discipline. Greenhouse gas emissions, supplier practices, workforce data, water usage, safety records, cyber resilience, and climate-risk exposure often sit across fragmented systems outside the general ledger. The information may be collected by operations, procurement, HR, facilities, legal, risk, or sustainability teams. It may be estimated, manually consolidated, or stored in spreadsheets. It may lack clear ownership, consistent definitions, or audit-ready evidence.

This creates a new accountability problem. Companies are being asked to disclose sustainability information with financial-statement seriousness, but many still manage the underlying data with pre-financial-statement infrastructure.

Accounting is now central to closing that gap.

Why Sustainability Reporting Is Becoming a Finance Issue

Sustainability reporting has historically been associated with reputation, values, and stakeholder communication. Those elements remain relevant, but the center of gravity has shifted toward financial materiality, enterprise risk, capital allocation, and long-term value creation.

Climate risk can affect asset values, insurance costs, supply chains, energy expenses, regulatory exposure, and capital investment. Workforce practices can affect retention, productivity, litigation risk, and brand position. Governance failures can affect valuation, borrowing costs, and investor confidence. Supply chain sustainability can determine access to large customers and international markets. These are not peripheral issues. They are business variables.

As sustainability factors become more closely tied to financial performance, the reporting burden naturally moves toward the CFO, controller, audit committee, and internal control environment. Investors do not only want broad claims about responsibility. They want measurable information that helps them assess risk and future cash flows.

This is consistent with the direction of major sustainability frameworks. The International Sustainability Standards Board’s IFRS S1 and IFRS S2 are designed to place sustainability-related financial disclosures alongside general-purpose financial reporting. Their structure emphasizes governance, strategy, risk management, and metrics and targets. That architecture resembles the logic of financial reporting: define the risk, explain the governance process, disclose the measurement basis, and connect the information to enterprise value.

The implication is clear. Sustainability reporting is becoming less like a brochure and more like a controlled reporting process.

The Integration Problem

Despite the rising importance of ESG data, integration with traditional accounting remains difficult. The main obstacle is not a lack of disclosure ambition. It is the weakness of the data architecture.

Financial reporting has spent decades building systems of record, reconciliation procedures, internal controls, review hierarchies, audit trails, and standard-setting bodies. Sustainability reporting is still building many of those mechanisms. In many organizations, ESG information is collected through a patchwork of emails, surveys, third-party platforms, local business-unit submissions, supplier questionnaires, and manual spreadsheets.

This creates five recurring problems.

First, definitions are inconsistent. One business unit may define energy use differently from another. One region may classify emissions using different assumptions. One supplier may report estimated data while another reports measured data. Without standard definitions, company-wide disclosure becomes difficult to compare and defend.

Second, ownership is unclear. Finance may be responsible for the annual report, sustainability may own ESG narratives, operations may own facilities data, HR may own workforce metrics, procurement may own supplier information, and legal may own disclosure risk. If ownership is distributed but accountability is not defined, reporting quality suffers.

Third, systems are disconnected. ESG data often does not flow through enterprise resource planning systems or financial consolidation platforms. It may sit in operational tools that were not designed for external reporting.

Fourth, timing is misaligned. Financial reporting runs on defined monthly, quarterly, and annual close cycles. Sustainability data may be gathered annually, after the fact, or in response to reporting deadlines. This creates pressure when companies need more current information.

Fifth, assurance readiness is uneven. Many companies can explain their sustainability goals but struggle to provide evidence for the underlying metrics. Assurance requires documentation, control, consistency, and traceability. Aspirational reporting does not meet that standard.

These issues are familiar to accountants. They are the same issues that financial reporting systems are designed to solve.

From ESG Disclosure to ESG Control

The next phase of sustainability reporting will require companies to treat ESG metrics as controlled information. This does not mean every sustainability metric must immediately receive the same level of control as revenue or inventory. It does mean companies must identify which metrics are material, decision-useful, externally reported, or connected to executive commitments, and then apply appropriate controls.

A practical control model includes four layers.

The first layer is metric governance. Companies should define each reported metric, identify its owner, document the calculation method, specify the data source, and determine whether estimates are used. This is the equivalent of establishing an accounting policy for non-financial data.

The second layer is data lineage. Reporting teams should be able to trace a disclosed figure back to its source. If a company reports Scope 1 emissions, workforce safety rates, supplier diversity spend, water consumption, or renewable energy use, it should know where the data came from, who reviewed it, and what assumptions were applied.

The third layer is review and certification. Business units should certify submitted ESG data in a structured manner. Finance, legal, sustainability, and internal audit should review high-risk disclosures before publication.

The fourth layer is assurance readiness. Companies should prepare for external assurance by maintaining documentation, evidence, and version control. Even where assurance is not yet mandatory, investors and boards increasingly expect reporting processes that can withstand scrutiny.

This is where accounting professionals create value. Their role is not to become climate scientists or social policy experts. Their role is to bring discipline to measurement, control, review, and disclosure.

The Demand for Real-Time Data

Sustainability reporting is also becoming more time-sensitive. Annual reporting alone is insufficient for many risks. Climate events, supply chain disruptions, energy price volatility, regulatory changes, and stakeholder pressure can emerge quickly. Companies need the ability to monitor ESG-related indicators throughout the year, not only during reporting season.

This does not mean every ESG metric must be reported in real time to the public. It means management needs more current internal data to make decisions.

For example, a manufacturer may need near-real-time energy and emissions data to manage production costs and carbon exposure. A retailer may need supplier-risk monitoring to identify disruptions or labor concerns. A logistics company may need fleet emissions data to evaluate fuel efficiency and regulatory exposure. A financial institution may need climate-risk data to assess portfolio concentration.

Accounting and finance teams are positioned to connect these operating metrics to financial implications. Energy use becomes cost analysis. Emissions exposure becomes regulatory and capital planning. Supplier practices become risk management. Workforce metrics become productivity and retention analysis.

This is the transition from ESG reporting to ESG management.

Measurement Frameworks: The Search for Comparability

One of the most important developments in sustainability reporting is the push toward greater comparability. Companies, investors, and regulators have long struggled with multiple frameworks, including GRI, SASB, TCFD, ISSB standards, ESRS under the European sustainability regime, and industry-specific reporting requirements. Each framework has a different orientation, audience, and disclosure philosophy.

The ISSB approach is significant because it seeks to establish a global baseline for sustainability-related financial disclosures. IFRS S1 provides general requirements for sustainability-related risks and opportunities, while IFRS S2 focuses on climate-related disclosures. The framework is designed around investor decision-making and enterprise value.

The European approach under the Corporate Sustainability Reporting Directive is broader. It uses a double-materiality lens, requiring companies to assess both how sustainability issues affect the company and how the company affects people and the environment. This creates a wider reporting obligation, including more extensive environmental, social, and governance data.

For multinational companies, the practical issue is interoperability. A company may need to report under one framework for investors, another for European compliance, another for customers, and another for voluntary sustainability communication. The risk is duplication, inconsistency, and excessive reporting burden.

The solution is not to build separate reporting processes for each framework. Companies should create a core sustainability data model that maps metrics across regimes. Accounting teams can help establish this model by applying familiar principles: standard chart of accounts logic, consistent definitions, data owners, reconciliation procedures, and reporting calendars.

The objective is to create one controlled source of truth that can support multiple reporting outputs.

Case Pattern: The Manufacturer That Treated Emissions as Cost Intelligence

Consider a multinational manufacturer with rising energy costs, supplier disclosure requests, and exposure to climate reporting requirements in multiple jurisdictions. Initially, the company treated emissions reporting as an annual compliance exercise. Facilities teams collected utility data. Sustainability staff consolidated the information. Finance reviewed the final report late in the process.

The company’s disclosures improved, but management value remained limited. Data arrived too late to influence operational decisions.

The finance team then redesigned the process. Energy and emissions data were integrated into monthly operating reviews. Facilities data was standardized across regions. Finance created a reporting bridge between energy use, production volume, unit cost, and emissions intensity. Internal audit reviewed the control process. Sustainability and operations used the same dataset for external reporting and internal performance management.

The result was not simply better disclosure. The company could identify facilities with abnormal energy intensity, evaluate capital investments in efficiency, and explain emissions trends in financial terms. Sustainability reporting became a management tool.

This is the model more companies will need. ESG metrics should not exist only for external reporting. They should inform operational and financial decisions.

Case Pattern: The Financial Institution That Linked Climate Risk to Portfolio Review

A second pattern is emerging in financial services. Banks, insurers, and asset managers increasingly need to evaluate climate-related exposure across portfolios. This requires data that may be incomplete, estimated, or dependent on counterparties.

A financial institution that treats climate reporting only as an annual disclosure task may struggle to connect the information to risk appetite, underwriting, pricing, or capital planning. A more mature approach integrates climate-risk data into portfolio review. Sector exposure, geographic risk, transition risk, collateral vulnerability, and financed emissions are evaluated alongside traditional credit and market risk indicators.

Accounting and risk teams play a central role because the output must be credible enough for board oversight and investor communication. The goal is not perfect prediction. It is disciplined, transparent, and decision-useful analysis.

In this model, sustainability reporting becomes part of enterprise risk management rather than an isolated ESG function.

Strategic Recommendations for Leaders

Senior leaders should approach sustainability reporting as a reporting architecture challenge.

First, assign clear ownership. ESG reporting cannot succeed if it belongs everywhere and nowhere. The CFO, general counsel, chief sustainability officer, internal audit, and operating leaders should have defined responsibilities. The audit committee should understand which sustainability metrics are material, assured, or connected to financial reporting.

Second, conduct a metric inventory. Companies should list all externally reported sustainability metrics, identify their sources, define calculation methods, and determine the level of control currently applied. This inventory should include voluntary reports, investor presentations, customer disclosures, website claims, and regulatory filings.

Third, prioritize material metrics. Not every ESG measure deserves the same investment. Companies should focus first on metrics that are financially material, regulatorily required, investor-relevant, operationally important, or tied to public commitments.

Fourth, build control procedures before assurance deadlines arrive. Waiting until assurance is required creates unnecessary risk. Companies should develop evidence standards, review processes, and data documentation now.

Fifth, integrate ESG data with financial planning. Sustainability information should influence capital allocation, risk modeling, procurement, operational efficiency, insurance, and scenario planning. Reporting should reflect strategy, not sit apart from it.

Sixth, invest in technology, but do not outsource judgment. ESG software can improve collection, workflow, and analytics. AI tools can help identify inconsistencies, summarize disclosures, and monitor regulatory change. But technology cannot determine materiality, resolve conflicting assumptions, or replace professional accountability.

Seventh, communicate with discipline. Companies should avoid broad claims that are difficult to support. Credible sustainability reporting is specific, measured, and connected to risk and performance. The strongest disclosures explain both progress and uncertainty.

Accounting’s Expanding Mandate

The accounting profession is entering a wider field of responsibility. Financial statements remain central, but the definition of decision-useful corporate information is expanding. Sustainability metrics are increasingly part of how investors evaluate resilience, risk, and long-term value.

This creates an opportunity for accounting leaders. They can help turn ESG reporting from fragmented disclosure into controlled business intelligence. They can bring rigor to measurement, consistency to definitions, discipline to review, and credibility to external communication.

The companies that succeed will not be those that publish the longest sustainability reports. They will be those that build the most reliable sustainability reporting systems.

In 2026, ESG accountability depends less on ambition and more on infrastructure. Accounting is the function best positioned to build it.