Explainer: Data interoperability & climate APIs — what it is, why it matters, and how to evaluate options

In 2024, the climate data analytics market reached an estimated $1.1 to $2.5 billion globally, with projections suggesting it will exceed $5 billion by 2030—a compound annual growth rate of 12 to 32 percent depending on scope (Mordor Intelligence, 2024). Yet despite this explosive growth, a critical bottleneck persists: limited data interoperability across platforms, providers, and regulatory frameworks continues to impede effective Scope 3 emissions tracking and cross-organisational sustainability reporting. The Partnership for Carbon Transparency (PACT) reports that over 4 million product carbon footprints have been generated across its ecosystem, demonstrating clear demand—but fragmentation remains the defining challenge. For sustainability professionals, understanding how to navigate climate APIs and data interoperability is no longer optional; it is fundamental to compliance, credibility, and competitive advantage.

Why It Matters

The urgency of climate action has elevated sustainability from a peripheral concern to a boardroom priority. Regulatory mandates—including the EU's Corporate Sustainability Reporting Directive (CSRD), the SEC's proposed climate disclosure rules, and California's Climate Corporate Data Accountability Act—now require granular emissions data across entire value chains. Scope 3 emissions, which typically represent 70 to 90 percent of a company's carbon footprint, demand supplier-level data that most organisations simply cannot access without robust interoperability frameworks.

The economic case is equally compelling. According to research from Verdantix, the climate financial data market was valued at $468 million in 2022 and is projected to exceed $1.3 billion by 2028, growing at 19 percent annually. Companies in the top quartile of data maturity report 7 to 9 percent operating cost savings through energy optimisation and streamlined reporting workflows. Conversely, organisations relying on fragmented, manually reconciled datasets face escalating compliance costs, audit failures, and reputational risk.

Climate APIs—application programming interfaces that enable automated, standardised data exchange between platforms—represent the infrastructure layer enabling this transformation. When implemented effectively, they reduce manual data handling errors by up to 80 percent, accelerate reporting cycles from months to days, and enable real-time decision-making based on accurate emissions intelligence.

Key Concepts

Data Interoperability

Data interoperability refers to the ability of diverse systems, platforms, and data formats to communicate, exchange, and interpret information seamlessly. In the climate context, this means enabling a carbon accounting platform to ingest emissions factors from a lifecycle assessment database, reconcile supplier-reported product carbon footprints, and export aggregated data to regulatory reporting frameworks—all without manual intervention or format conversion.

The WBCSD's PACT framework exemplifies this approach. Launched as the Pathfinder Framework and now evolved to Version 3 (released April 2025), PACT establishes both a methodology for calculating product carbon footprints and a technical specification—an HTTP REST API standard—for exchanging this data across any conformant solution. This creates what the framework describes as "email-like interoperability": just as Gmail users can send messages to Outlook recipients, organisations using different carbon accounting platforms can exchange verified emissions data without bilateral integration projects.

Climate APIs

Climate APIs provide programmatic access to climate-relevant datasets, including weather and climate projections, emissions factors, carbon intensity data, and supply chain emissions information. These APIs typically return data in standardised formats (JSON, CSV, or NetCDF) and support filtering by geography, time period, sector, and data quality indicators.

Key categories include:

• Weather and Climate Projection APIs: Platforms like Open-Meteo, Tomorrow.io, and Meteomatics provide historical climate data, real-time observations, and forward-looking projections from models including CMIP6.
• Emissions Factor APIs: Services like Climatiq, CEDA (acquired by Watershed), and OpenLCA provide access to emissions factor databases covering thousands of materials, processes, and activities.
• Carbon Footprint Exchange APIs: The PACT Technical Specifications define the standard for peer-to-peer product carbon footprint exchange, enabling primary data sharing between suppliers and buyers.
• ESG and Climate Risk APIs: Enterprise platforms from MSCI, Bloomberg, and S&P Global offer investment-grade climate risk scores, scenario analysis, and regulatory compliance data.

Product Carbon Footprints and Scope 3

A product carbon footprint (PCF) quantifies the greenhouse gas emissions associated with a product across its lifecycle—from raw material extraction through manufacturing, distribution, use, and end-of-life. For purchasing organisations, supplier PCFs are essential to calculating Scope 3 emissions (Category 1: Purchased Goods and Services), which often represent the largest share of corporate emissions.

The challenge lies in data quality and consistency. Without standardised methodologies and exchange protocols, organisations must either use generic industry-average emissions factors (introducing significant uncertainty) or engage in resource-intensive bilateral data collection exercises. The PACT framework addresses this by establishing mandatory Data Quality Indicators (DQIs) that all exchanged PCFs must include, enabling recipients to assess and compare data reliability systematically.

Sector-Specific KPI Benchmarks

Evaluating climate API and interoperability solutions requires understanding what "good" looks like across key performance dimensions:

Metric	Laggard (<P25)	Median (P50)	Leader (>P75)	Notes
Data Coverage (% of Scope 3 categories with primary data)	<20%	35-50%	>70%	Primary data reduces uncertainty by 40-60% vs industry averages
API Response Time (95th percentile)	>5 seconds	1-2 seconds	<500ms	Critical for real-time procurement decisions
Data Refresh Frequency	Quarterly or less	Monthly	Weekly or real-time	Regulatory reporting increasingly requires recent data
Emissions Factor Database Coverage	<5,000 factors	10,000-20,000	>50,000	Broader coverage reduces reliance on proxy data
System Integration Time	>6 months	2-4 months	<4 weeks	PACT-conformant solutions typically deploy faster
Audit Trail Completeness	Partial or manual	Automated with gaps	Full provenance chain	Essential for assurance-ready reporting

What's Working and What Isn't

What's Working

Standardisation momentum is accelerating. The PACT ecosystem now includes over 150 partners and 30 conformant technology solutions, with 2,500 businesses having calculated or exchanged product carbon footprints during the pilot phase. This critical mass creates network effects: each additional participant increases the value of the network for all members. The Carbon Trust has verified over 37,000 product carbon footprints using PACT-aligned methodologies, demonstrating that scalable assurance is achievable.

Enterprise adoption has reached mainstream. Watershed's February 2024 Series C funding of $100 million—valuing the company at $1.8 billion—reflects market confidence in carbon accounting infrastructure. The company reports that four of the top six US banks and major corporations including BlackRock, Walmart, and Airbnb have deployed its platform. Similarly, Persefoni's Climate Management and Accounting Platform serves four of the ten largest global private equity firms, indicating that climate data infrastructure is no longer experimental.

Open data initiatives are expanding access. Climate TRACE now offers a free, publicly accessible API providing monthly emissions data by source, sector, and geography—released under Creative Commons licensing. This democratises access to satellite-derived emissions intelligence that was previously available only to well-resourced organisations. NOAA's Climate Data Online API and the European Centre for Medium-Range Weather Forecasts (ECMWF) have similarly expanded programmatic access to climate observations and projections.

What Isn't Working

Scope 3 data quality remains inconsistent. Despite methodological advances, most organisations still rely heavily on spend-based or industry-average emissions factors for Scope 3 calculations. A 2024 Forrester analysis found that the limited data interoperability and standardisation continues to thwart aggregation attempts across providers, with organisations frequently requiring data from multiple sources to meet ESG and climate-risk reporting requirements.

SME participation lags. While enterprise adoption accelerates, small and medium-sized enterprises—which comprise the majority of supply chain tiers—often lack the resources and technical capacity to implement climate APIs or calculate product carbon footprints. This creates data gaps precisely where primary data is most needed.

Regulatory fragmentation persists. Despite alignment efforts, the EU's CSRD, SEC's proposed rules, California's disclosure requirements, and ISSB standards retain meaningful differences in scope, metrics, and timing. Climate data platforms must maintain multiple reporting outputs, increasing complexity and cost.

Key Players

Established Leaders

MSCI offers nearly 2,250 climate change metrics covering 20,000 issuers, used by 43 of the top 50 global asset managers. Their Climate Value-at-Risk methodology has become an industry standard for portfolio climate risk assessment.

S&P Global provides Trucost environmental data alongside credit ratings and indices, offering integrated climate risk intelligence for financial institutions.

Bloomberg delivers ESG data through its terminal platform, with climate analytics embedded into the workflows of investment professionals globally.

Schneider Electric combines sustainability consulting with its EcoStruxure platform, offering end-to-end carbon management for industrial and commercial clients.

CDP (formerly Carbon Disclosure Project) operates the world's largest corporate environmental disclosure platform, collecting data from over 23,000 companies annually and increasingly integrating PACT-conformant data exchange.

Emerging Startups

Watershed ($225 million raised, $1.8 billion valuation) provides enterprise sustainability software integrating carbon accounting, supplier engagement, and decarbonisation planning—with the CEDA emissions factor database embedded.

Persefoni ($179 million raised) positions its Climate Management and Accounting Platform as "ERP for Carbon Data," with a free tier (Persefoni Pro) that attracted 6,000 sign-ups within months of launch.

Climatiq offers a carbon intelligence API with what it describes as the world's largest carbon impact database, enabling developers to embed emissions calculations into any application.

Normative (Sweden-based) focuses on automated carbon accounting with strong EU regulatory alignment, recently partnered with major enterprise software providers.

Sweep combines carbon tracking with actionable reduction roadmaps, emphasising supplier collaboration and Scope 3 transparency.

Key Investors and Funders

Sequoia Capital and Kleiner Perkins have backed Watershed, signalling mainstream venture confidence in climate data infrastructure.

TPG Rise Fund led Persefoni's record-breaking $101 million Series B and continues to support the company through its Series C, representing significant growth equity commitment.

Greenoaks led Watershed's $100 million Series C, valuing the company at $1.8 billion.

Prelude Ventures focuses exclusively on climate technology, with investments across the carbon accounting and data infrastructure landscape.

Galvanize Climate Solutions and Emerson Collective represent mission-aligned capital sources increasingly active in the sector.

Examples

1. Unilever and PACT-Enabled Supplier Engagement

Unilever, with supply chain emissions representing the vast majority of its carbon footprint, has integrated PACT-conformant data exchange into its supplier engagement programme. By enabling automated collection of product carbon footprints from key suppliers, the company reduced the time required for Scope 3 data collection by over 60 percent while improving data quality from industry-average to primary-data quality for high-impact categories. This approach informed targeted decarbonisation investments in packaging and raw material sourcing.

2. BlackRock's Climate Risk Analytics Integration

BlackRock, managing over $10 trillion in assets, deploys climate data APIs from multiple providers—including MSCI Climate Value-at-Risk and proprietary Aladdin Climate analytics—to assess portfolio-level transition and physical risk. The integration of standardised climate scenarios (aligned with NGFS pathways) enables consistent stress testing across asset classes, informing both risk management and client reporting. The firm's adoption of Watershed for operational carbon accounting demonstrates how enterprises layer specialised tools for comprehensive coverage.

3. Siemens and Digital Twin Climate Integration

Siemens integrates climate projection APIs into its digital twin platforms for buildings and industrial facilities, enabling predictive energy management that accounts for future climate scenarios. By incorporating CMIP6 projections and real-time weather data, facilities can optimise HVAC operations for both current efficiency and long-term resilience, achieving 15 to 25 percent energy savings while maintaining occupant comfort under changing climate conditions.

Action Checklist

• Audit current data landscape: Map all existing climate data sources, formats, and manual reconciliation processes to identify fragmentation and integration opportunities.
• Evaluate PACT conformance: Assess whether current or prospective carbon accounting platforms are PACT-conformant, enabling automated supplier data exchange.
• Prioritise Scope 3 categories: Identify the three to five Scope 3 categories contributing most to your footprint and develop targeted primary data collection strategies.
• Establish data quality thresholds: Define minimum acceptable Data Quality Indicators for different reporting purposes, distinguishing screening estimates from assurance-ready data.
• Develop API integration roadmap: Create a phased implementation plan for climate API integrations, prioritising highest-value use cases and quick wins.
• Engage suppliers early: Communicate data requirements and provide resources (including PACT training materials) to strategic suppliers before regulatory deadlines create bottlenecks.
• Build internal capacity: Invest in training for sustainability and IT teams on climate data standards, API integration, and data governance best practices.

FAQ

Q: How do PACT and CDP relate—are they competing standards? A: PACT and CDP are complementary rather than competing. CDP operates a disclosure platform where companies report environmental data annually. PACT provides the methodology and technical specifications for calculating and exchanging product carbon footprints that can then be aggregated for CDP reporting. CDP's PCF calculation tool is PACT-conformant, enabling seamless data flow between supplier-level carbon accounting and corporate disclosure platforms.

Q: What's the difference between using emissions factor APIs versus requesting primary data from suppliers? A: Emissions factor APIs provide secondary data—industry or regional averages derived from lifecycle assessment databases. This data is readily accessible but introduces uncertainty (typically ±30-50% for Scope 3 categories). Primary data, such as supplier-specific product carbon footprints, reflects actual production processes and can reduce uncertainty by 40-60 percent. The ideal approach uses primary data for high-impact suppliers and emissions factor APIs for long-tail categories where primary data is impractical.

Q: How long does it typically take to implement a climate API integration? A: Implementation timelines vary significantly based on scope and organisational readiness. Simple emissions calculator integrations (embedding Climatiq or similar APIs into existing applications) can be completed in days to weeks. Enterprise carbon accounting platform deployments typically require 2-4 months for leading solutions, extending to 6+ months for organisations with complex legacy systems or extensive customisation requirements. PACT-conformant solutions generally deploy faster due to standardised interfaces.

Q: What should we look for when evaluating climate data providers? A: Key evaluation criteria include: emissions factor database coverage and update frequency; API reliability and response times; data provenance and audit trail capabilities; regulatory alignment (CSRD, ISSB, SEC, California); integration ecosystem and pre-built connectors; pricing model transparency; and customer support quality. Request reference customers in your sector and conduct proof-of-concept testing with representative data before committing.

Q: How do we ensure data quality when aggregating from multiple sources? A: Establish a data governance framework that includes: clear data quality indicator requirements for each use case; automated validation rules that flag outliers and missing fields; documented data lineage tracking sources through transformations; regular reconciliation between bottom-up calculations and top-down estimates; and periodic third-party verification for material categories. The PACT methodology's mandatory DQIs provide a useful baseline for supplier-provided PCFs.

Sources

• Mordor Intelligence, "Climate Data Analytics Market Size & Growth to 2030," 2024. Available at: mordorintelligence.com/industry-reports/climate-data-analytics-market
• Verdantix, "Market Size and Forecast: Climate Financial Data and Analytics 2022-2028," 2024. Available at: verdantix.com
• WBCSD, "Partnership for Carbon Transparency (PACT) Methodology V3," April 2025. Available at: carbon-transparency.org/pact-methodology
• Watershed, "Watershed Announces $100M in New Funding," February 2024. Available at: globenewswire.com
• Persefoni, "Persefoni Secures Series C Investment," March 2025. Available at: businesswire.com
• Forrester, "What You Should Look For From ESG and Climate Data and Analytics Providers," 2024. Available at: forrester.com
• Climate TRACE, "Data Downloads and API Documentation," 2024. Available at: climatetrace.org/data
• Carbon Trust, "PACT: Unlocking Product Carbon Data for More Sustainable Value Chains," 2025. Available at: carbontrust.com