Nearly $1 trillion in sustainable loans were signed in 2024, according to Environmental Finance. Sustainability-linked loans now account for more than 60% of that market.
This is no longer niche. It is mainstream corporate finance.
The verification infrastructure behind it has not kept pace.
This gap is becoming a structural problem for banks, for regulators, and for the credibility of sustainable finance itself.
Verification has not scaled with issuance
The UK Financial Conduct Authority reviewed the SLL market in 2023 and raised significant concerns. One participating bank estimated that only 30% of its 250 sustainability-linked loans were fit for purpose. Half lacked robust KPIs. The FCA observed that "relationship may matter more than the borrower's sustainability credentials" in lending decisions.
Research from the Principles for Responsible Investment found that borrower ESG scores often deteriorate after SLL issuance. Precisely the opposite of the instrument's intent.
This is not a data quality problem in the traditional sense.
Banks with net zero commitments are not demanding perfect emissions figures today. What matters is whether progress can be measured consistently from a credible baseline. Whether borrowers are moving in the right direction and whether that movement can be tracked over time.
Full assurance standards will come. In the interim, institutions are adopting a range of verification approaches, some independent, some internal, to build confidence incrementally. The goal is not to wait for a perfect framework, but to create defensible evidence of progress now.
The question is not whether data is perfect. The question is whether trajectory can be tracked at scale, anomalies flagged, and reliance reconstructed when required.
Manual verification does not scale
A single analyst can track one borrower's performance from baseline to current. Across a portfolio of hundreds of sustainability-linked facilities, each with different KPIs, reporting cycles, and document types, consistency breaks down.
Verification is typically annual and backward looking. Borrowers self-report. External assurance validates a point in time. Between verification cycles, exposure accumulates without visibility.
When a credit committee asks what was relied upon, or a regulator examines the basis for a pricing decision, institutions need more than a compliance certificate. They need the evidence chain. What documents were submitted, what confidence can be placed in them, how they connect to the reported figures.
Disclosure frameworks established a common language. Assurance standards introduced periodic validation. Neither provides continuous tracking. Neither creates audit grade traceability linking reported outcomes to underlying evidence across the life of a facility.
Regulation is moving toward verifiability
The 2025 updates to the Sustainability-Linked Loan Principles introduced new language. KPIs must now be "externally verifiable where feasible" and "consistent with the borrower's overall sustainability strategy."
The direction is clear. What enters the balance sheet must be reconstructable.
Infrastructure, not calculation
The market is not short of carbon calculators. Emissions can be estimated, scopes categorised, reports generated.
What is missing is infrastructure. The layer that connects every claim to its source, assesses document quality, tracks consistency over time, and allows institutions to understand not only what was reported, but what can be relied upon.
When a borrower submits evidence of KPI achievement, the question is not only whether the target was met. It is whether the underlying documentation is credible. A system generated invoice carries different weight than a handwritten receipt. Consistency across reporting periods signals reliability. Anomalies signal risk.
This layer does not replace assurance. It creates the foundation that makes assurance possible and makes interim reliance defensible.
The transition underway
Sustainability-linked finance will continue to grow. Regulatory expectations will tighten. The institutions that build robust verification infrastructure will have a structural advantage. Lower greenwashing risk, stronger credit committee confidence, clearer audit trails.
Those waiting for perfect standards will find the market has moved without them.
Disclosure established the language. Assurance introduced periodic checks. The next layer is validation infrastructure. Continuous, traceable, built for financial grade reliance.
Carbon AI is that infrastructure.
