Deep dive: Sustainable finance data & ESG ratings reform — what's working, what's not, and what's next

The sustainable finance data ecosystem is undergoing its most significant structural transformation since the concept of ESG investing entered mainstream capital markets. ESG ratings from major providers diverge so widely that the correlation between MSCI and Sustainalytics scores for the same company averages just 0.54, compared to 0.99 for credit ratings from Moody's and S&P. This divergence has created a credibility crisis that regulators, standard setters, and market participants are now actively working to resolve. Understanding where reform efforts stand, what is delivering results, and what remains broken is essential for any organization navigating sustainable finance in emerging markets and beyond.

Why It Matters

Global sustainable investment assets reached $35.3 trillion in 2024, representing approximately 36% of total assets under management across major markets, according to the Global Sustainable Investment Alliance. Yet the data infrastructure underpinning these allocation decisions remains fragmented, inconsistent, and in many cases unreliable. A 2024 study by MIT Sloan found that ESG rating disagreement across six major providers was not randomly distributed but systematically biased against companies in emerging markets, where data availability is lower and reporting frameworks are less mature.

The regulatory landscape has intensified pressure for reform. The EU's Corporate Sustainability Reporting Directive (CSRD), effective for large companies from fiscal year 2024, mandates detailed sustainability disclosures aligned with the European Sustainability Reporting Standards (ESRS). The International Sustainability Standards Board (ISSB) published IFRS S1 and S2, establishing a global baseline for sustainability and climate disclosures that over 20 jurisdictions have committed to adopt or reference. India's SEBI mandated Business Responsibility and Sustainability Reporting (BRSR) for the top 1,000 listed companies, while Brazil's CVM introduced mandatory climate risk disclosures aligned with ISSB standards beginning in 2026.

For emerging market economies, the stakes are particularly high. Capital allocation decisions influenced by ESG ratings directly affect sovereign borrowing costs, foreign direct investment flows, and access to concessional climate finance. A 2025 World Bank analysis estimated that ESG data gaps cost emerging market issuers an aggregate $12-18 billion annually in higher financing costs relative to peers with comparable fundamentals but better data coverage.

Key Concepts

ESG Ratings Divergence refers to the well-documented phenomenon where different rating agencies assign materially different ESG scores to the same entity. The sources of divergence include differences in scope (what categories are measured), measurement (how indicators are quantified), and weight (how categories are aggregated). Research by Berg, Koelbel, and Rigobon at MIT identified measurement divergence as the dominant driver, accounting for approximately 56% of total disagreement. This means that even when providers agree on what to measure, they reach different conclusions about the same underlying data.

Double Materiality is the principle that companies should report on sustainability matters that are both financially material (affecting enterprise value) and impact material (affecting society and the environment). The CSRD adopts a full double materiality approach, while ISSB standards focus primarily on financial materiality with investor-oriented disclosures. This philosophical difference creates a structural tension in the global reporting architecture that affects how data is collected, verified, and used in investment decisions.

Assured Sustainability Data refers to sustainability disclosures that have been independently verified by third-party assurance providers. The CSRD requires limited assurance for sustainability reports initially, with a transition to reasonable assurance (equivalent to financial audit standards) anticipated by 2028. Currently, fewer than 30% of sustainability disclosures globally receive any form of independent assurance, and coverage in emerging markets falls below 12%.

Taxonomy Alignment measures the proportion of a company's revenue, capital expenditure, or operating expenditure that qualifies as environmentally sustainable under a regulatory classification system. The EU Taxonomy is the most developed framework, defining technical screening criteria for six environmental objectives. Emerging market jurisdictions including South Africa, Colombia, and ASEAN member states have developed or are developing their own taxonomies, often with different scope and thresholds.

ESG Data Quality: Benchmark Ranges

Metric	Below Average	Average	Above Average	Top Quartile
Company ESG Data Coverage (Developed Markets)	<60%	60-75%	75-85%	>85%
Company ESG Data Coverage (Emerging Markets)	<30%	30-50%	50-65%	>65%
Rating Provider Correlation (Same Company)	<0.40	0.40-0.55	0.55-0.70	>0.70
Assured Sustainability Disclosures	<10%	10-25%	25-45%	>45%
Taxonomy Alignment Reporting	<5% of revenue	5-15%	15-30%	>30%
Data Lag (Months from Period End)	>12 months	8-12 months	4-8 months	<4 months
Scope 3 Data Availability	<15%	15-30%	30-50%	>50%

What's Working

ISSB Standards Adoption and Convergence

The single most consequential development in sustainable finance data is the rapid adoption trajectory of ISSB standards. By early 2026, 23 jurisdictions had formally committed to incorporating IFRS S1 and S2 into their regulatory frameworks, including the UK, Japan, Singapore, Nigeria, and Brazil. This convergence is beginning to address the fragmentation that plagued sustainability reporting for two decades. Japan's Financial Services Agency mandated ISSB-aligned disclosures for listed companies beginning April 2025, creating a compliance catalyst across the world's third-largest equity market. Singapore's SGX required climate reporting aligned with ISSB for all listed companies from fiscal year 2025. The critical effect is standardization of data definitions, reporting boundaries, and disclosure formats, which directly improves comparability and reduces the measurement divergence that drives rating disagreement.

Technology-Enabled Data Collection

Satellite imagery, natural language processing, and alternative data sources are filling critical gaps in emerging market ESG data coverage. Companies like Clarity AI process over 30,000 data sources using machine learning to estimate emissions for companies that do not disclose. Kayrros uses satellite-based methane detection to verify corporate emissions claims against observed atmospheric concentrations. Arabesque S-Ray applies big data analytics to over 4 million daily signals across news, NGO reports, and government databases to generate real-time ESG assessments. These approaches have increased effective data coverage for emerging market companies from approximately 25% in 2022 to over 45% in 2025, reducing the information asymmetry that historically penalized issuers in developing economies.

EU ESG Rating Provider Regulation

The EU adopted regulation on ESG rating activities in 2024, establishing authorization requirements, governance standards, and conflict-of-interest safeguards for rating providers operating in European markets. Providers must now disclose their methodologies, data sources, and the limitations of their assessments. They must separate rating activities from advisory and consulting services to prevent conflicts of interest. ESMA assumed supervisory authority over authorized providers beginning in 2025. While the regulation does not mandate methodological convergence (which would undermine analytical diversity), the transparency requirements give data users the information needed to understand what drives rating differences and make informed decisions about which assessments to rely upon.

What's Not Working

Emerging Market Data Infrastructure

Despite technological advances, fundamental data infrastructure gaps persist in emerging markets. Companies in Sub-Saharan Africa, Southeast Asia, and Latin America frequently lack the internal systems, expertise, and incentives to collect and report granular sustainability data. A 2025 IFC survey found that 68% of listed companies in frontier markets had no dedicated sustainability reporting function, and 54% lacked the metering infrastructure to measure Scope 1 and 2 emissions accurately. The result is a two-tier system where companies in data-rich markets receive nuanced assessments while those in data-poor markets are evaluated based on estimates, sector averages, or country-level proxies that may not reflect actual performance.

Greenwashing and Data Integrity

The proliferation of sustainability disclosures has outpaced verification capacity. Inflated or misleading claims remain widespread, particularly in fund-level marketing. A 2025 Morningstar analysis found that 41% of funds marketed as "sustainable" in Europe held at least one company deriving more than 5% of revenue from fossil fuel extraction. The EU's Sustainable Finance Disclosure Regulation (SFDR) reclassification exercise resulted in over 1,200 Article 9 ("dark green") funds being downgraded to Article 8 ("light green") between 2023 and 2025, suggesting that initial classifications were often aspirational rather than evidence-based.

Scope 3 Measurement Uncertainty

Scope 3 emissions, which typically represent 70-90% of a company's total carbon footprint, remain the weakest link in climate data quality. Estimation methodologies vary widely, producing ranges that can differ by 300-500% for the same company depending on the approach used. The GHG Protocol's ongoing Scope 3 standard revision aims to improve consistency, but convergence on measurement approaches remains years away. For financial institutions, financed emissions calculations compound this uncertainty because they depend on portfolio companies' Scope 3 data, creating cascading measurement noise that undermines the reliability of climate risk assessments.

Rating Methodology Opacity

Despite regulatory progress, many ESG rating providers continue to treat their methodologies as proprietary intellectual property, limiting the ability of rated entities and data users to understand, challenge, or verify assessments. A 2024 survey by the CFA Institute found that 72% of institutional investors were unable to fully replicate or explain the ESG ratings they used in investment decisions. This opacity is particularly problematic for emerging market issuers who may receive lower ratings due to methodology choices (such as penalizing countries with lower GDP per capita or less developed regulatory frameworks) rather than actual sustainability performance.

What's Next

Interoperability and Digital Reporting

The most important near-term development is the shift toward machine-readable, interoperable sustainability data. The ISSB's digital taxonomy enables XBRL-tagged sustainability disclosures that can be processed, compared, and analyzed programmatically at scale. The EU's European Single Access Point (ESAP), expected to launch in 2027, will provide centralized access to corporate sustainability data in structured digital formats. For emerging markets, the IFRS Foundation's partnership with regional bodies including the African Financial Reporting Advisory Group (AFRAG) and the Pan-Asian ESG Alliance aims to build local capacity for digital reporting infrastructure that connects to global data ecosystems.

Mandatory Assurance Expansion

Independent assurance of sustainability data will become standard practice over the next three to five years. The CSRD's transition from limited to reasonable assurance, combined with the IAASB's International Standard on Sustainability Assurance (ISSA 5000), will establish audit-grade expectations for sustainability disclosures. Early evidence from the EU's first wave of CSRD reporters suggests that assured disclosures contain 30-40% fewer material misstatements than unassured reports. The International Auditing and Assurance Standards Board finalized ISSA 5000 in late 2024, providing a framework that jurisdiction-specific requirements can reference.

AI-Driven Ratings and Real-Time Assessment

The next generation of ESG data products will move beyond annual, backward-looking assessments to continuous monitoring. Platforms combining satellite data, supply chain tracking, workforce sentiment analysis, and regulatory filings can generate near-real-time sustainability risk signals. RepRisk already processes over 100,000 sources daily to identify ESG incidents within 24-48 hours of occurrence. As these capabilities mature and incorporate structured data from digital reporting frameworks, the traditional annual ESG rating cycle will give way to dynamic, event-driven assessments that better reflect actual risk exposure.

Emerging Market Capacity Building

Multilateral development banks and development finance institutions are scaling programs to improve sustainability data quality in developing economies. The IFC's Sustainability Reporting Toolkit, launched in 2025, provides standardized templates and training for companies in over 60 countries. The Asian Development Bank's climate data initiative is deploying IoT-enabled emissions monitoring in industrial facilities across South and Southeast Asia. These programs recognize that sustainable finance cannot deliver on its capital allocation promise if half the world's economies remain data-dark.

Action Checklist

• Map current ESG data consumption across the organization, identifying which ratings, data providers, and methodologies inform investment or lending decisions
• Assess data coverage and quality gaps for emerging market exposures using multiple provider scores and disclosed methodology documentation
• Implement processes to cross-reference ESG ratings with primary data sources (satellite imagery, regulatory databases, company filings) for material positions
• Prepare for ISSB-aligned reporting requirements by inventorying current disclosure practices against IFRS S1 and S2 requirements
• Engage assurance providers to scope limited or reasonable assurance for sustainability disclosures ahead of regulatory mandates
• Evaluate AI-augmented ESG data platforms that offer improved coverage, timeliness, and transparency for emerging market portfolios
• Establish internal governance for ESG data usage, including documentation of which ratings influence decisions and how methodological limitations are addressed

FAQ

Q: Why do ESG ratings from different providers disagree so much? A: Disagreement stems from three sources: scope (what is measured), measurement (how it is measured), and weight (how categories are combined). Research shows measurement divergence is the largest contributor, meaning providers interpret the same underlying data differently. Unlike credit ratings, there is no established mathematical relationship between ESG factors and a single outcome variable, so reasonable methodological choices can produce materially different results.

Q: How should investors handle ESG rating divergence in portfolio construction? A: Best practice is to use multiple ratings as inputs rather than relying on a single provider. Decompose aggregate scores into component pillars and indicators to identify where providers agree (which signals stronger evidence) and where they disagree (which signals uncertainty requiring further analysis). For material positions, supplement ratings with primary research, company engagement, and alternative data sources.

Q: What does ISSB adoption mean for companies reporting under different frameworks? A: ISSB standards are designed as a global baseline that jurisdictions can build upon. Companies currently reporting under GRI, CDP, or jurisdiction-specific frameworks should map existing disclosures to IFRS S1 and S2 to identify gaps. The ISSB and GRI have published interoperability guidance to support companies reporting under both frameworks. Over time, jurisdictional adoption will reduce the total number of frameworks companies must navigate.

Q: Are emerging market companies disadvantaged by current ESG rating approaches? A: Evidence suggests systematic bias exists. Lower data availability, less developed regulatory frameworks, and country-level risk adjustments can result in lower ratings for emerging market companies relative to developed market peers with similar or worse actual sustainability performance. Reforms including improved data infrastructure, technology-enabled coverage, and regulatory transparency requirements are beginning to address this gap.

Q: How reliable are AI-estimated ESG data for companies that do not disclose? A: AI estimates have improved significantly but remain less reliable than reported and assured data. Accuracy varies by metric: emissions estimates based on sector, size, and geography proxies can deviate 25-50% from actual values, while governance and social indicators estimated from alternative data sources show higher uncertainty. AI estimates are most useful for screening and flagging, not for precise measurement or compliance purposes.

Sources

• Berg, F., Koelbel, J.F., and Rigobon, R. (2022). Aggregate Confusion: The Divergence of ESG Ratings. Review of Finance, 26(6), 1315-1344.
• Global Sustainable Investment Alliance. (2025). Global Sustainable Investment Review 2024. Brussels: GSIA.
• International Financial Reporting Standards Foundation. (2025). IFRS S1 and S2 Adoption Tracker. London: IFRS Foundation.
• Morningstar. (2025). SFDR Article 8 and Article 9 Funds: Landscape and Greenwashing Analysis. Chicago: Morningstar Research.
• World Bank Group / International Finance Corporation. (2025). ESG Data Gaps and Financing Costs in Emerging Markets. Washington, DC: IFC.
• European Securities and Markets Authority. (2025). ESG Rating Activities Regulation: Implementation Report. Paris: ESMA.
• CFA Institute. (2024). ESG Integration and Data Quality: Global Institutional Investor Survey. Charlottesville, VA: CFA Institute.
• International Auditing and Assurance Standards Board. (2024). ISSA 5000: General Requirements for Sustainability Assurance Engagements. New York: IAASB.